/*-------------------------------------------------------------------------
*
* planner.c
* The query optimizer external interface.
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/optimizer/plan/planner.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <limits.h>
#include <math.h>
#include "access/genam.h"
#include "access/htup_details.h"
#include "access/parallel.h"
#include "access/sysattr.h"
#include "access/table.h"
#include "access/xact.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "executor/executor.h"
#include "executor/nodeAgg.h"
#include "foreign/fdwapi.h"
#include "jit/jit.h"
#include "lib/bipartite_match.h"
#include "lib/knapsack.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#ifdef OPTIMIZER_DEBUG
#include "nodes/print.h"
#endif
#include "optimizer/appendinfo.h"
#include "optimizer/clauses.h"
#include "optimizer/cost.h"
#include "optimizer/inherit.h"
#include "optimizer/optimizer.h"
#include "optimizer/paramassign.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/plancat.h"
#include "optimizer/planmain.h"
#include "optimizer/planner.h"
#include "optimizer/prep.h"
#include "optimizer/subselect.h"
#include "optimizer/tlist.h"
#include "parser/analyze.h"
#include "parser/parse_agg.h"
#include "parser/parsetree.h"
#include "partitioning/partdesc.h"
#include "rewrite/rewriteManip.h"
#include "storage/dsm_impl.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/selfuncs.h"
#include "utils/syscache.h"
/* GUC parameters */
double cursor_tuple_fraction = DEFAULT_CURSOR_TUPLE_FRACTION;
int force_parallel_mode = FORCE_PARALLEL_OFF;
bool parallel_leader_participation = true;
/* Hook for plugins to get control in planner() */
planner_hook_type planner_hook = NULL;
/* Hook for plugins to get control when grouping_planner() plans upper rels */
create_upper_paths_hook_type create_upper_paths_hook = NULL;
/* Expression kind codes for preprocess_expression */
#define EXPRKIND_QUAL 0
#define EXPRKIND_TARGET 1
#define EXPRKIND_RTFUNC 2
#define EXPRKIND_RTFUNC_LATERAL 3
#define EXPRKIND_VALUES 4
#define EXPRKIND_VALUES_LATERAL 5
#define EXPRKIND_LIMIT 6
#define EXPRKIND_APPINFO 7
#define EXPRKIND_PHV 8
#define EXPRKIND_TABLESAMPLE 9
#define EXPRKIND_ARBITER_ELEM 10
#define EXPRKIND_TABLEFUNC 11
#define EXPRKIND_TABLEFUNC_LATERAL 12
/* Passthrough data for standard_qp_callback */
typedef struct
{
List *activeWindows; /* active windows, if any */
List *groupClause; /* overrides parse->groupClause */
} standard_qp_extra;
/*
* Data specific to grouping sets
*/
typedef struct
{
List *rollups;
List *hash_sets_idx;
double dNumHashGroups;
bool any_hashable;
Bitmapset *unsortable_refs;
Bitmapset *unhashable_refs;
List *unsortable_sets;
int *tleref_to_colnum_map;
} grouping_sets_data;
/*
* Temporary structure for use during WindowClause reordering in order to be
* able to sort WindowClauses on partitioning/ordering prefix.
*/
typedef struct
{
WindowClause *wc;
List *uniqueOrder; /* A List of unique ordering/partitioning
* clauses per Window */
} WindowClauseSortData;
/* Local functions */
static Node *preprocess_expression(PlannerInfo *root, Node *expr, int kind);
static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode);
static void grouping_planner(PlannerInfo *root, double tuple_fraction);
static grouping_sets_data *preprocess_grouping_sets(PlannerInfo *root);
static List *remap_to_groupclause_idx(List *groupClause, List *gsets,
int *tleref_to_colnum_map);
static void preprocess_rowmarks(PlannerInfo *root);
static double preprocess_limit(PlannerInfo *root,
double tuple_fraction,
int64 *offset_est, int64 *count_est);
static void remove_useless_groupby_columns(PlannerInfo *root);
static List *preprocess_groupclause(PlannerInfo *root, List *force);
static List *extract_rollup_sets(List *groupingSets);
static List *reorder_grouping_sets(List *groupingSets, List *sortclause);
static void standard_qp_callback(PlannerInfo *root, void *extra);
static double get_number_of_groups(PlannerInfo *root,
double path_rows,
grouping_sets_data *gd,
List *target_list);
static RelOptInfo *create_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
PathTarget *target,
bool target_parallel_safe,
grouping_sets_data *gd);
static bool is_degenerate_grouping(PlannerInfo *root);
static void create_degenerate_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *grouped_rel);
static RelOptInfo *make_grouping_rel(PlannerInfo *root, RelOptInfo *input_rel,
PathTarget *target, bool target_parallel_safe,
Node *havingQual);
static void create_ordinary_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *grouped_rel,
const AggClauseCosts *agg_costs,
grouping_sets_data *gd,
GroupPathExtraData *extra,
RelOptInfo **partially_grouped_rel_p);
static void consider_groupingsets_paths(PlannerInfo *root,
RelOptInfo *grouped_rel,
Path *path,
bool is_sorted,
bool can_hash,
grouping_sets_data *gd,
const AggClauseCosts *agg_costs,
double dNumGroups);
static RelOptInfo *create_window_paths(PlannerInfo *root,
RelOptInfo *input_rel,
PathTarget *input_target,
PathTarget *output_target,
bool output_target_parallel_safe,
WindowFuncLists *wflists,
List *activeWindows);
static void create_one_window_path(PlannerInfo *root,
RelOptInfo *window_rel,
Path *path,
PathTarget *input_target,
PathTarget *output_target,
WindowFuncLists *wflists,
List *activeWindows);
static RelOptInfo *create_distinct_paths(PlannerInfo *root,
RelOptInfo *input_rel);
static RelOptInfo *create_ordered_paths(PlannerInfo *root,
RelOptInfo *input_rel,
PathTarget *target,
bool target_parallel_safe,
double limit_tuples);
static PathTarget *make_group_input_target(PlannerInfo *root,
PathTarget *final_target);
static PathTarget *make_partial_grouping_target(PlannerInfo *root,
PathTarget *grouping_target,
Node *havingQual);
static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
static List *select_active_windows(PlannerInfo *root, WindowFuncLists *wflists);
static PathTarget *make_window_input_target(PlannerInfo *root,
PathTarget *final_target,
List *activeWindows);
static List *make_pathkeys_for_window(PlannerInfo *root, WindowClause *wc,
List *tlist);
static PathTarget *make_sort_input_target(PlannerInfo *root,
PathTarget *final_target,
bool *have_postponed_srfs);
static void adjust_paths_for_srfs(PlannerInfo *root, RelOptInfo *rel,
List *targets, List *targets_contain_srfs);
static void add_paths_to_grouping_rel(PlannerInfo *root, RelOptInfo *input_rel,
RelOptInfo *grouped_rel,
RelOptInfo *partially_grouped_rel,
const AggClauseCosts *agg_costs,
grouping_sets_data *gd,
double dNumGroups,
GroupPathExtraData *extra);
static RelOptInfo *create_partial_grouping_paths(PlannerInfo *root,
RelOptInfo *grouped_rel,
RelOptInfo *input_rel,
grouping_sets_data *gd,
GroupPathExtraData *extra,
bool force_rel_creation);
static void gather_grouping_paths(PlannerInfo *root, RelOptInfo *rel);
static bool can_partial_agg(PlannerInfo *root);
static void apply_scanjoin_target_to_paths(PlannerInfo *root,
RelOptInfo *rel,
List *scanjoin_targets,
List *scanjoin_targets_contain_srfs,
bool scanjoin_target_parallel_safe,
bool tlist_same_exprs);
static void create_partitionwise_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *grouped_rel,
RelOptInfo *partially_grouped_rel,
const AggClauseCosts *agg_costs,
grouping_sets_data *gd,
PartitionwiseAggregateType patype,
GroupPathExtraData *extra);
static bool group_by_has_partkey(RelOptInfo *input_rel,
List *targetList,
List *groupClause);
static int common_prefix_cmp(const void *a, const void *b);
/*****************************************************************************
*
* Query optimizer entry point
*
* To support loadable plugins that monitor or modify planner behavior,
* we provide a hook variable that lets a plugin get control before and
* after the standard planning process. The plugin would normally call
* standard_planner().
*
* Note to plugin authors: standard_planner() scribbles on its Query input,
* so you'd better copy that data structure if you want to plan more than once.
*
*****************************************************************************/
PlannedStmt *
planner(Query *parse, const char *query_string, int cursorOptions,
ParamListInfo boundParams)
{
PlannedStmt *result;
if (planner_hook)
result = (*planner_hook) (parse, query_string, cursorOptions, boundParams);
else
result = standard_planner(parse, query_string, cursorOptions, boundParams);
return result;
}
PlannedStmt *
standard_planner(Query *parse, const char *query_string, int cursorOptions,
ParamListInfo boundParams)
{
PlannedStmt *result;
PlannerGlobal *glob;
double tuple_fraction;
PlannerInfo *root;
RelOptInfo *final_rel;
Path *best_path;
Plan *top_plan;
ListCell *lp,
*lr;
/*
* Set up global state for this planner invocation. This data is needed
* across all levels of sub-Query that might exist in the given command,
* so we keep it in a separate struct that's linked to by each per-Query
* PlannerInfo.
*/
glob = makeNode(PlannerGlobal);
glob->boundParams = boundParams;
glob->subplans = NIL;
glob->subroots = NIL;
glob->rewindPlanIDs = NULL;
glob->finalrtable = NIL;
glob->finalrowmarks = NIL;
glob->resultRelations = NIL;
glob->appendRelations = NIL;
glob->relationOids = NIL;
glob->invalItems = NIL;
glob->paramExecTypes = NIL;
glob->lastPHId = 0;
glob->lastRowMarkId = 0;
glob->lastPlanNodeId = 0;
glob->transientPlan = false;
glob->dependsOnRole = false;
/*
* Assess whether it's feasible to use parallel mode for this query. We
* can't do this in a standalone backend, or if the command will try to
* modify any data, or if this is a cursor operation, or if GUCs are set
* to values that don't permit parallelism, or if parallel-unsafe
* functions are present in the query tree.
*
* (Note that we do allow CREATE TABLE AS, SELECT INTO, and CREATE
* MATERIALIZED VIEW to use parallel plans, but as of now, only the leader
* backend writes into a completely new table. In the future, we can
* extend it to allow workers to write into the table. However, to allow
* parallel updates and deletes, we have to solve other problems,
* especially around combo CIDs.)
*
* For now, we don't try to use parallel mode if we're running inside a
* parallel worker. We might eventually be able to relax this
* restriction, but for now it seems best not to have parallel workers
* trying to create their own parallel workers.
*/
if ((cursorOptions & CURSOR_OPT_PARALLEL_OK) != 0 &&
IsUnderPostmaster &&
parse->commandType == CMD_SELECT &&
!parse->hasModifyingCTE &&
max_parallel_workers_per_gather > 0 &&
!IsParallelWorker())
{
/* all the cheap tests pass, so scan the query tree */
glob->maxParallelHazard = max_parallel_hazard(parse);
glob->parallelModeOK = (glob->maxParallelHazard != PROPARALLEL_UNSAFE);
}
else
{
/* skip the query tree scan, just assume it's unsafe */
glob->maxParallelHazard = PROPARALLEL_UNSAFE;
glob->parallelModeOK = false;
}
/*
* glob->parallelModeNeeded is normally set to false here and changed to
* true during plan creation if a Gather or Gather Merge plan is actually
* created (cf. create_gather_plan, create_gather_merge_plan).
*
* However, if force_parallel_mode = on or force_parallel_mode = regress,
* then we impose parallel mode whenever it's safe to do so, even if the
* final plan doesn't use parallelism. It's not safe to do so if the
* query contains anything parallel-unsafe; parallelModeOK will be false
* in that case. Note that parallelModeOK can't change after this point.
* Otherwise, everything in the query is either parallel-safe or
* parallel-restricted, and in either case it should be OK to impose
* parallel-mode restrictions. If that ends up breaking something, then
* either some function the user included in the query is incorrectly
* labeled as parallel-safe or parallel-restricted when in reality it's
* parallel-unsafe, or else the query planner itself has a bug.
*/
glob->parallelModeNeeded = glob->parallelModeOK &&
(force_parallel_mode != FORCE_PARALLEL_OFF);
/* Determine what fraction of the plan is likely to be scanned */
if (cursorOptions & CURSOR_OPT_FAST_PLAN)
{
/*
* We have no real idea how many tuples the user will ultimately FETCH
* from a cursor, but it is often the case that he doesn't want 'em
* all, or would prefer a fast-start plan anyway so that he can
* process some of the tuples sooner. Use a GUC parameter to decide
* what fraction to optimize for.
*/
tuple_fraction = cursor_tuple_fraction;
/*
* We document cursor_tuple_fraction as simply being a fraction, which
* means the edge cases 0 and 1 have to be treated specially here. We
* convert 1 to 0 ("all the tuples") and 0 to a very small fraction.
*/
if (tuple_fraction >= 1.0)
tuple_fraction = 0.0;
else if (tuple_fraction <= 0.0)
tuple_fraction = 1e-10;
}
else
{
/* Default assumption is we need all the tuples */
tuple_fraction = 0.0;
}
/* primary planning entry point (may recurse for subqueries) */
root = subquery_planner(glob, parse, NULL,
false, tuple_fraction);
/* Select best Path and turn it into a Plan */
final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL);
best_path = get_cheapest_fractional_path(final_rel, tuple_fraction);
top_plan = create_plan(root, best_path);
/*
* If creating a plan for a scrollable cursor, make sure it can run
* backwards on demand. Add a Material node at the top at need.
*/
if (cursorOptions & CURSOR_OPT_SCROLL)
{
if (!ExecSupportsBackwardScan(top_plan))
top_plan = materialize_finished_plan(top_plan);
}
/*
* Optionally add a Gather node for testing purposes, provided this is
* actually a safe thing to do.
*/
if (force_parallel_mode != FORCE_PARALLEL_OFF && top_plan->parallel_safe)
{
Gather *gather = makeNode(Gather);
/*
* If there are any initPlans attached to the formerly-top plan node,
* move them up to the Gather node; same as we do for Material node in
* materialize_finished_plan.
*/
gather->plan.initPlan = top_plan->initPlan;
top_plan->initPlan = NIL;
gather->plan.targetlist = top_plan->targetlist;
gather->plan.qual = NIL;
gather->plan.lefttree = top_plan;
gather->plan.righttree = NULL;
gather->num_workers = 1;
gather->single_copy = true;
gather->invisible = (force_parallel_mode == FORCE_PARALLEL_REGRESS);
/*
* Since this Gather has no parallel-aware descendants to signal to,
* we don't need a rescan Param.
*/
gather->rescan_param = -1;
/*
* Ideally we'd use cost_gather here, but setting up dummy path data
* to satisfy it doesn't seem much cleaner than knowing what it does.
*/
gather->plan.startup_cost = top_plan->startup_cost +
parallel_setup_cost;
gather->plan.total_cost = top_plan->total_cost +
parallel_setup_cost + parallel_tuple_cost * top_plan->plan_rows;
gather->plan.plan_rows = top_plan->plan_rows;
gather->plan.plan_width = top_plan->plan_width;
gather->plan.parallel_aware = false;
gather->plan.parallel_safe = false;
/* use parallel mode for parallel plans. */
root->glob->parallelModeNeeded = true;
top_plan = &gather->plan;
}
/*
* If any Params were generated, run through the plan tree and compute
* each plan node's extParam/allParam sets. Ideally we'd merge this into
* set_plan_references' tree traversal, but for now it has to be separate
* because we need to visit subplans before not after main plan.
*/
if (glob->paramExecTypes != NIL)
{
Assert(list_length(glob->subplans) == list_length(glob->subroots));
forboth(lp, glob->subplans, lr, glob->subroots)
{
Plan *subplan = (Plan *) lfirst(lp);
PlannerInfo *subroot = lfirst_node(PlannerInfo, lr);
SS_finalize_plan(subroot, subplan);
}
SS_finalize_plan(root, top_plan);
}
/* final cleanup of the plan */
Assert(glob->finalrtable == NIL);
Assert(glob->finalrowmarks == NIL);
Assert(glob->resultRelations == NIL);
Assert(glob->appendRelations == NIL);
top_plan = set_plan_references(root, top_plan);
/* ... and the subplans (both regular subplans and initplans) */
Assert(list_length(glob->subplans) == list_length(glob->subroots));
forboth(lp, glob->subplans, lr, glob->subroots)
{
Plan *subplan = (Plan *) lfirst(lp);
PlannerInfo *subroot = lfirst_node(PlannerInfo, lr);
lfirst(lp) = set_plan_references(subroot, subplan);
}
/* build the PlannedStmt result */
result = makeNode(PlannedStmt);
result->commandType = parse->commandType;
result->queryId = parse->queryId;
result->hasReturning = (parse->returningList != NIL);
result->hasModifyingCTE = parse->hasModifyingCTE;
result->canSetTag = parse->canSetTag;
result->transientPlan = glob->transientPlan;
result->dependsOnRole = glob->dependsOnRole;
result->parallelModeNeeded = glob->parallelModeNeeded;
result->planTree = top_plan;
result->rtable = glob->finalrtable;
result->resultRelations = glob->resultRelations;
result->appendRelations = glob->appendRelations;
result->subplans = glob->subplans;
result->rewindPlanIDs = glob->rewindPlanIDs;
result->rowMarks = glob->finalrowmarks;
result->relationOids = glob->relationOids;
result->invalItems = glob->invalItems;
result->paramExecTypes = glob->paramExecTypes;
/* utilityStmt should be null, but we might as well copy it */
result->utilityStmt = parse->utilityStmt;
result->stmt_location = parse->stmt_location;
result->stmt_len = parse->stmt_len;
result->jitFlags = PGJIT_NONE;
if (jit_enabled && jit_above_cost >= 0 &&
top_plan->total_cost > jit_above_cost)
{
result->jitFlags |= PGJIT_PERFORM;
/*
* Decide how much effort should be put into generating better code.
*/
if (jit_optimize_above_cost >= 0 &&
top_plan->total_cost > jit_optimize_above_cost)
result->jitFlags |= PGJIT_OPT3;
if (jit_inline_above_cost >= 0 &&
top_plan->total_cost > jit_inline_above_cost)
result->jitFlags |= PGJIT_INLINE;
/*
* Decide which operations should be JITed.
*/
if (jit_expressions)
result->jitFlags |= PGJIT_EXPR;
if (jit_tuple_deforming)
result->jitFlags |= PGJIT_DEFORM;
}
if (glob->partition_directory != NULL)
DestroyPartitionDirectory(glob->partition_directory);
return result;
}
/*--------------------
* subquery_planner
* Invokes the planner on a subquery. We recurse to here for each
* sub-SELECT found in the query tree.
*
* glob is the global state for the current planner run.
* parse is the querytree produced by the parser & rewriter.
* parent_root is the immediate parent Query's info (NULL at the top level).
* hasRecursion is true if this is a recursive WITH query.
* tuple_fraction is the fraction of tuples we expect will be retrieved.
* tuple_fraction is interpreted as explained for grouping_planner, below.
*
* Basically, this routine does the stuff that should only be done once
* per Query object. It then calls grouping_planner. At one time,
* grouping_planner could be invoked recursively on the same Query object;
* that's not currently true, but we keep the separation between the two
* routines anyway, in case we need it again someday.
*
* subquery_planner will be called recursively to handle sub-Query nodes
* found within the query's expressions and rangetable.
*
* Returns the PlannerInfo struct ("root") that contains all data generated
* while planning the subquery. In particular, the Path(s) attached to
* the (UPPERREL_FINAL, NULL) upperrel represent our conclusions about the
* cheapest way(s) to implement the query. The top level will select the
* best Path and pass it through createplan.c to produce a finished Plan.
*--------------------
*/
PlannerInfo *
subquery_planner(PlannerGlobal *glob, Query *parse,
PlannerInfo *parent_root,
bool hasRecursion, double tuple_fraction)
{
PlannerInfo *root;
List *newWithCheckOptions;
List *newHaving;
bool hasOuterJoins;
bool hasResultRTEs;
RelOptInfo *final_rel;
ListCell *l;
/* Create a PlannerInfo data structure for this subquery */
root = makeNode(PlannerInfo);
root->parse = parse;
root->glob = glob;
root->query_level = parent_root ? parent_root->query_level + 1 : 1;
root->parent_root = parent_root;
root->plan_params = NIL;
root->outer_params = NULL;
root->planner_cxt = CurrentMemoryContext;
root->init_plans = NIL;
root->cte_plan_ids = NIL;
root->multiexpr_params = NIL;
root->eq_classes = NIL;
root->ec_merging_done = false;
root->all_result_relids =
parse->resultRelation ? bms_make_singleton(parse->resultRelation) : NULL;
root->leaf_result_relids = NULL; /* we'll find out leaf-ness later */
root->append_rel_list = NIL;
root->row_identity_vars = NIL;
root->rowMarks = NIL;
memset(root->upper_rels, 0, sizeof(root->upper_rels));
memset(root->upper_targets, 0, sizeof(root->upper_targets));
root->processed_tlist = NIL;
root->update_colnos = NIL;
root->grouping_map = NULL;
root->minmax_aggs = NIL;
root->qual_security_level = 0;
root->hasPseudoConstantQuals = false;
root->hasAlternativeSubPlans = false;
root->hasRecursion = hasRecursion;
if (hasRecursion)
root->wt_param_id = assign_special_exec_param(root);
else
root->wt_param_id = -1;
root->non_recursive_path = NULL;
root->partColsUpdated = false;
/*
* If there is a WITH list, process each WITH query and either convert it
* to RTE_SUBQUERY RTE(s) or build an initplan SubPlan structure for it.
*/
if (parse->cteList)
SS_process_ctes(root);
/*
* If the FROM clause is empty, replace it with a dummy RTE_RESULT RTE, so
* that we don't need so many special cases to deal with that situation.
*/
replace_empty_jointree(parse);
/*
* Look for ANY and EXISTS SubLinks in WHERE and JOIN/ON clauses, and try
* to transform them into joins. Note that this step does not descend
* into subqueries; if we pull up any subqueries below, their SubLinks are
* processed just before pulling them up.
*/
if (parse->hasSubLinks)
pull_up_sublinks(root);
/*
* Scan the rangetable for function RTEs, do const-simplification on them,
* and then inline them if possible (producing subqueries that might get
* pulled up next). Recursion issues here are handled in the same way as
* for SubLinks.
*/
preprocess_function_rtes(root);
/*
* Check to see if any subqueries in the jointree can be merged into this
* query.
*/
pull_up_subqueries(root);
/*
* If this is a simple UNION ALL query, flatten it into an appendrel. We
* do this now because it requires applying pull_up_subqueries to the leaf
* queries of the UNION ALL, which weren't touched above because they
* weren't referenced by the jointree (they will be after we do this).
*/
if (parse->setOperations)
flatten_simple_union_all(root);
/*
* Survey the rangetable to see what kinds of entries are present. We can
* skip some later processing if relevant SQL features are not used; for
* example if there are no JOIN RTEs we can avoid the expense of doing
* flatten_join_alias_vars(). This must be done after we have finished
* adding rangetable entries, of course. (Note: actually, processing of
* inherited or partitioned rels can cause RTEs for their child tables to
* get added later; but those must all be RTE_RELATION entries, so they
* don't invalidate the conclusions drawn here.)
*/
root->hasJoinRTEs = false;
root->hasLateralRTEs = false;
hasOuterJoins = false;
hasResultRTEs = false;
foreach(l, parse->rtable)
{
RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
switch (rte->rtekind)
{
case RTE_RELATION:
if (rte->inh)
{
/*
* Check to see if the relation actually has any children;
* if not, clear the inh flag so we can treat it as a
* plain base relation.
*
* Note: this could give a false-positive result, if the
* rel once had children but no longer does. We used to
* be able to clear rte->inh later on when we discovered
* that, but no more; we have to handle such cases as
* full-fledged inheritance.
*/
rte->inh = has_subclass(rte->relid);
}
break;
case RTE_JOIN:
root->hasJoinRTEs = true;
if (IS_OUTER_JOIN(rte->jointype))
hasOuterJoins = true;
break;
case RTE_RESULT:
hasResultRTEs = true;
break;
default:
/* No work here for other RTE types */
break;
}
if (rte->lateral)
root->hasLateralRTEs = true;
/*
* We can also determine the maximum security level required for any
* securityQuals now. Addition of inheritance-child RTEs won't affect
* this, because child tables don't have their own securityQuals; see
* expand_single_inheritance_child().
*/
if (rte->securityQuals)
root->qual_security_level = Max(root->qual_security_level,
list_length(rte->securityQuals));
}
/*
* If we have now verified that the query target relation is
* non-inheriting, mark it as a leaf target.
*/
if (parse->resultRelation)
{
RangeTblEntry *rte = rt_fetch(parse->resultRelation, parse->rtable);
if (!rte->inh)
root->leaf_result_relids =
bms_make_singleton(parse->resultRelation);
}
/*
* Preprocess RowMark information. We need to do this after subquery
* pullup, so that all base relations are present.
*/
preprocess_rowmarks(root);
/*
* Set hasHavingQual to remember if HAVING clause is present. Needed
* because preprocess_expression will reduce a constant-true condition to
* an empty qual list ... but "HAVING TRUE" is not a semantic no-op.
*/
root->hasHavingQual = (parse->havingQual != NULL);
/*
* Do expression preprocessing on targetlist and quals, as well as other
* random expressions in the querytree. Note that we do not need to
* handle sort/group expressions explicitly, because they are actually
* part of the targetlist.
*/
parse->targetList = (List *)
preprocess_expression(root, (Node *) parse->targetList,
EXPRKIND_TARGET);
/* Constant-folding might have removed all set-returning functions */
if (parse->hasTargetSRFs)
parse->hasTargetSRFs = expression_returns_set((Node *) parse->targetList);
newWithCheckOptions = NIL;
foreach(l, parse->withCheckOptions)
{
WithCheckOption *wco = lfirst_node(WithCheckOption, l);
wco->qual = preprocess_expression(root, wco->qual,
EXPRKIND_QUAL);
if (wco->qual != NULL)
newWithCheckOptions = lappend(newWithCheckOptions, wco);
}
parse->withCheckOptions = newWithCheckOptions;
parse->returningList = (List *)
preprocess_expression(root, (Node *) parse->returningList,
EXPRKIND_TARGET);
preprocess_qual_conditions(root, (Node *) parse->jointree);
parse->havingQual = preprocess_expression(root, parse->havingQual,
EXPRKIND_QUAL);
foreach(l, parse->windowClause)
{
WindowClause *wc = lfirst_node(WindowClause, l);
/* partitionClause/orderClause are sort/group expressions */
wc->startOffset = preprocess_expression(root, wc->startOffset,
EXPRKIND_LIMIT);
wc->endOffset = preprocess_expression(root, wc->endOffset,
EXPRKIND_LIMIT);
}
parse->limitOffset = preprocess_expression(root, parse->limitOffset,
EXPRKIND_LIMIT);
parse->limitCount = preprocess_expression(root, parse->limitCount,
EXPRKIND_LIMIT);
if (parse->onConflict)
{
parse->onConflict->arbiterElems = (List *)
preprocess_expression(root,
(Node *) parse->onConflict->arbiterElems,
EXPRKIND_ARBITER_ELEM);
parse->onConflict->arbiterWhere =
preprocess_expression(root,
parse->onConflict->arbiterWhere,
EXPRKIND_QUAL);
parse->onConflict->onConflictSet = (List *)
preprocess_expression(root,
(Node *) parse->onConflict->onConflictSet,
EXPRKIND_TARGET);
parse->onConflict->onConflictWhere =
preprocess_expression(root,
parse->onConflict->onConflictWhere,
EXPRKIND_QUAL);
/* exclRelTlist contains only Vars, so no preprocessing needed */
}
root->append_rel_list = (List *)
preprocess_expression(root, (Node *) root->append_rel_list,
EXPRKIND_APPINFO);
/* Also need to preprocess expressions within RTEs */
foreach(l, parse->rtable)
{
RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
int kind;
ListCell *lcsq;
if (rte->rtekind == RTE_RELATION)
{
if (rte->tablesample)
rte->tablesample = (TableSampleClause *)
preprocess_expression(root,
(Node *) rte->tablesample,
EXPRKIND_TABLESAMPLE);
}
else if (rte->rtekind == RTE_SUBQUERY)
{
/*
* We don't want to do all preprocessing yet on the subquery's
* expressions, since that will happen when we plan it. But if it
* contains any join aliases of our level, those have to get
* expanded now, because planning of the subquery won't do it.
* That's only possible if the subquery is LATERAL.
*/
if (rte->lateral && root->hasJoinRTEs)
rte->subquery = (Query *)
flatten_join_alias_vars(root->parse,
(Node *) rte->subquery);
}
else if (rte->rtekind == RTE_FUNCTION)
{
/* Preprocess the function expression(s) fully */
kind = rte->lateral ? EXPRKIND_RTFUNC_LATERAL : EXPRKIND_RTFUNC;
rte->functions = (List *)
preprocess_expression(root, (Node *) rte->functions, kind);
}
else if (rte->rtekind == RTE_TABLEFUNC)
{
/* Preprocess the function expression(s) fully */
kind = rte->lateral ? EXPRKIND_TABLEFUNC_LATERAL : EXPRKIND_TABLEFUNC;
rte->tablefunc = (TableFunc *)
preprocess_expression(root, (Node *) rte->tablefunc, kind);
}
else if (rte->rtekind == RTE_VALUES)
{
/* Preprocess the values lists fully */
kind = rte->lateral ? EXPRKIND_VALUES_LATERAL : EXPRKIND_VALUES;
rte->values_lists = (List *)
preprocess_expression(root, (Node *) rte->values_lists, kind);
}
/*
* Process each element of the securityQuals list as if it were a
* separate qual expression (as indeed it is). We need to do it this
* way to get proper canonicalization of AND/OR structure. Note that
* this converts each element into an implicit-AND sublist.
*/
foreach(lcsq, rte->securityQuals)
{
lfirst(lcsq) = preprocess_expression(root,
(Node *) lfirst(lcsq),
EXPRKIND_QUAL);
}
}
/*
* Now that we are done preprocessing expressions, and in particular done
* flattening join alias variables, get rid of the joinaliasvars lists.
* They no longer match what expressions in the rest of the tree look
* like, because we have not preprocessed expressions in those lists (and
* do not want to; for example, expanding a SubLink there would result in
* a useless unreferenced subplan). Leaving them in place simply creates
* a hazard for later scans of the tree. We could try to prevent that by
* using QTW_IGNORE_JOINALIASES in every tree scan done after this point,
* but that doesn't sound very reliable.
*/
if (root->hasJoinRTEs)
{
foreach(l, parse->rtable)
{
RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
rte->joinaliasvars = NIL;
}
}
/*
* In some cases we may want to transfer a HAVING clause into WHERE. We
* cannot do so if the HAVING clause contains aggregates (obviously) or
* volatile functions (since a HAVING clause is supposed to be executed
* only once per group). We also can't do this if there are any nonempty
* grouping sets; moving such a clause into WHERE would potentially change
* the results, if any referenced column isn't present in all the grouping
* sets. (If there are only empty grouping sets, then the HAVING clause
* must be degenerate as discussed below.)
*
* Also, it may be that the clause is so expensive to execute that we're
* better off doing it only once per group, despite the loss of
* selectivity. This is hard to estimate short of doing the entire
* planning process twice, so we use a heuristic: clauses containing
* subplans are left in HAVING. Otherwise, we move or copy the HAVING
* clause into WHERE, in hopes of eliminating tuples before aggregation
* instead of after.
*
* If the query has explicit grouping then we can simply move such a
* clause into WHERE; any group that fails the clause will not be in the
* output because none of its tuples will reach the grouping or
* aggregation stage. Otherwise we must have a degenerate (variable-free)
* HAVING clause, which we put in WHERE so that query_planner() can use it
* in a gating Result node, but also keep in HAVING to ensure that we
* don't emit a bogus aggregated row. (This could be done better, but it
* seems not worth optimizing.)
*
* Note that both havingQual and parse->jointree->quals are in
* implicitly-ANDed-list form at this point, even though they are declared
* as Node *.
*/
newHaving = NIL;
foreach(l, (List *) parse->havingQual)
{
Node *havingclause = (Node *) lfirst(l);
if ((parse->groupClause && parse->groupingSets) ||
contain_agg_clause(havingclause) ||
contain_volatile_functions(havingclause) ||
contain_subplans(havingclause))
{
/* keep it in HAVING */
newHaving = lappend(newHaving, havingclause);
}
else if (parse->groupClause && !parse->groupingSets)
{
/* move it to WHERE */
parse->jointree->quals = (Node *)
lappend((List *) parse->jointree->quals, havingclause);
}
else
{
/* put a copy in WHERE, keep it in HAVING */
parse->jointree->quals = (Node *)
lappend((List *) parse->jointree->quals,
copyObject(havingclause));
newHaving = lappend(newHaving, havingclause);
}
}
parse->havingQual = (Node *) newHaving;
/* Remove any redundant GROUP BY columns */
remove_useless_groupby_columns(root);
/*
* If we have any outer joins, try to reduce them to plain inner joins.
* This step is most easily done after we've done expression
* preprocessing.
*/
if (hasOuterJoins)
reduce_outer_joins(root);
/*
* If we have any RTE_RESULT relations, see if they can be deleted from
* the jointree. This step is most effectively done after we've done
* expression preprocessing and outer join reduction.
*/
if (hasResultRTEs)
remove_useless_result_rtes(root);
/*
* Do the main planning.
*/
grouping_planner(root, tuple_fraction);
/*
* Capture the set of outer-level param IDs we have access to, for use in
* extParam/allParam calculations later.
*/
SS_identify_outer_params(root);
/*
* If any initPlans were created in this query level, adjust the surviving
* Paths' costs and parallel-safety flags to account for them. The
* initPlans won't actually get attached to the plan tree till
* create_plan() runs, but we must include their effects now.
*/
final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL);
SS_charge_for_initplans(root, final_rel);
/*
* Make sure we've identified the cheapest Path for the final rel. (By
* doing this here not in grouping_planner, we include initPlan costs in
* the decision, though it's unlikely that will change anything.)
*/
set_cheapest(final_rel);
return root;
}
/*
* preprocess_expression
* Do subquery_planner's preprocessing work for an expression,
* which can be a targetlist, a WHERE clause (including JOIN/ON
* conditions), a HAVING clause, or a few other things.
*/
static Node *
preprocess_expression(PlannerInfo *root, Node *expr, int kind)
{
/*
* Fall out quickly if expression is empty. This occurs often enough to
* be worth checking. Note that null->null is the correct conversion for
* implicit-AND result format, too.
*/
if (expr == NULL)
return NULL;
/*
* If the query has any join RTEs, replace join alias variables with
* base-relation variables. We must do this first, since any expressions
* we may extract from the joinaliasvars lists have not been preprocessed.
* For example, if we did this after sublink processing, sublinks expanded
* out from join aliases would not get processed. But we can skip this in
* non-lateral RTE functions, VALUES lists, and TABLESAMPLE clauses, since
* they can't contain any Vars of the current query level.
*/
if (root->hasJoinRTEs &&
!(kind == EXPRKIND_RTFUNC ||
kind == EXPRKIND_VALUES ||
kind == EXPRKIND_TABLESAMPLE ||
kind == EXPRKIND_TABLEFUNC))
expr = flatten_join_alias_vars(root->parse, expr);
/*
* Simplify constant expressions. For function RTEs, this was already
* done by preprocess_function_rtes ... but we have to do it again if the
* RTE is LATERAL and might have contained join alias variables.
*
* Note: an essential effect of this is to convert named-argument function
* calls to positional notation and insert the current actual values of
* any default arguments for functions. To ensure that happens, we *must*
* process all expressions here. Previous PG versions sometimes skipped
* const-simplification if it didn't seem worth the trouble, but we can't
* do that anymore.
*
* Note: this also flattens nested AND and OR expressions into N-argument
* form. All processing of a qual expression after this point must be
* careful to maintain AND/OR flatness --- that is, do not generate a tree
* with AND directly under AND, nor OR directly under OR.
*/
if (!(kind == EXPRKIND_RTFUNC ||
(kind == EXPRKIND_RTFUNC_LATERAL && !root->hasJoinRTEs)))
expr = eval_const_expressions(root, expr);
/*
* If it's a qual or havingQual, canonicalize it.
*/
if (kind == EXPRKIND_QUAL)
{
expr = (Node *) canonicalize_qual((Expr *) expr, false);
#ifdef OPTIMIZER_DEBUG
printf("After canonicalize_qual()\n");
pprint(expr);
#endif
}
/*
* Check for ANY ScalarArrayOpExpr with Const arrays and set the
* hashfuncid of any that might execute more quickly by using hash lookups
* instead of a linear search.
*/
if (kind == EXPRKIND_QUAL || kind == EXPRKIND_TARGET)
{
convert_saop_to_hashed_saop(expr);
}
/* Expand SubLinks to SubPlans */
if (root->parse->hasSubLinks)
expr = SS_process_sublinks(root, expr, (kind == EXPRKIND_QUAL));
/*
* XXX do not insert anything here unless you have grokked the comments in
* SS_replace_correlation_vars ...
*/
/* Replace uplevel vars with Param nodes (this IS possible in VALUES) */
if (root->query_level > 1)
expr = SS_replace_correlation_vars(root, expr);
/*
* If it's a qual or havingQual, convert it to implicit-AND format. (We
* don't want to do this before eval_const_expressions, since the latter
* would be unable to simplify a top-level AND correctly. Also,
* SS_process_sublinks expects explicit-AND format.)
*/
if (kind == EXPRKIND_QUAL)
expr = (Node *) make_ands_implicit((Expr *) expr);
return expr;
}
/*
* preprocess_qual_conditions
* Recursively scan the query's jointree and do subquery_planner's
* preprocessing work on each qual condition found therein.
*/
static void
preprocess_qual_conditions(PlannerInfo *root, Node *jtnode)
{
if (jtnode == NULL)
return;
if (IsA(jtnode, RangeTblRef))
{
/* nothing to do here */
}
else if (IsA(jtnode, FromExpr))
{
FromExpr *f = (FromExpr *) jtnode;
ListCell *l;
foreach(l, f->fromlist)
preprocess_qual_conditions(root, lfirst(l));
f->quals = preprocess_expression(root, f->quals, EXPRKIND_QUAL);
}
else if (IsA(jtnode, JoinExpr))
{
JoinExpr *j = (JoinExpr *) jtnode;
preprocess_qual_conditions(root, j->larg);
preprocess_qual_conditions(root, j->rarg);
j->quals = preprocess_expression(root, j->quals, EXPRKIND_QUAL);
}
else
elog(ERROR, "unrecognized node type: %d",
(int) nodeTag(jtnode));
}
/*
* preprocess_phv_expression
* Do preprocessing on a PlaceHolderVar expression that's been pulled up.
*
* If a LATERAL subquery references an output of another subquery, and that
* output must be wrapped in a PlaceHolderVar because of an intermediate outer
* join, then we'll push the PlaceHolderVar expression down into the subquery
* and later pull it back up during find_lateral_references, which runs after
* subquery_planner has preprocessed all the expressions that were in the
* current query level to start with. So we need to preprocess it then.
*/
Expr *
preprocess_phv_expression(PlannerInfo *root, Expr *expr)
{
return (Expr *) preprocess_expression(root, (Node *) expr, EXPRKIND_PHV);
}
/*--------------------
* grouping_planner
* Perform planning steps related to grouping, aggregation, etc.
*
* This function adds all required top-level processing to the scan/join
* Path(s) produced by query_planner.
*
* tuple_fraction is the fraction of tuples we expect will be retrieved.
* tuple_fraction is interpreted as follows:
* 0: expect all tuples to be retrieved (normal case)
* 0 < tuple_fraction < 1: expect the given fraction of tuples available
* from the plan to be retrieved
* tuple_fraction >= 1: tuple_fraction is the absolute number of tuples
* expected to be retrieved (ie, a LIMIT specification)
*
* Returns nothing; the useful output is in the Paths we attach to the
* (UPPERREL_FINAL, NULL) upperrel in *root. In addition,
* root->processed_tlist contains the final processed targetlist.
*
* Note that we have not done set_cheapest() on the final rel; it's convenient
* to leave this to the caller.
*--------------------
*/
static void
grouping_planner(PlannerInfo *root, double tuple_fraction)
{
Query *parse = root->parse;
int64 offset_est = 0;
int64 count_est = 0;
double limit_tuples = -1.0;
bool have_postponed_srfs = false;
PathTarget *final_target;
List *final_targets;
List *final_targets_contain_srfs;
bool final_target_parallel_safe;
RelOptInfo *current_rel;
RelOptInfo *final_rel;
FinalPathExtraData extra;
ListCell *lc;
/* Tweak caller-supplied tuple_fraction if have LIMIT/OFFSET */
if (parse->limitCount || parse->limitOffset)
{
tuple_fraction = preprocess_limit(root, tuple_fraction,
&offset_est, &count_est);
/*
* If we have a known LIMIT, and don't have an unknown OFFSET, we can
* estimate the effects of using a bounded sort.
*/
if (count_est > 0 && offset_est >= 0)
limit_tuples = (double) count_est + (double) offset_est;
}
/* Make tuple_fraction accessible to lower-level routines */
root->tuple_fraction = tuple_fraction;
if (parse->setOperations)
{
/*
* If there's a top-level ORDER BY, assume we have to fetch all the
* tuples. This might be too simplistic given all the hackery below
* to possibly avoid the sort; but the odds of accurate estimates here
* are pretty low anyway. XXX try to get rid of this in favor of
* letting plan_set_operations generate both fast-start and
* cheapest-total paths.
*/
if (parse->sortClause)
root->tuple_fraction = 0.0;
/*
* Construct Paths for set operations. The results will not need any
* work except perhaps a top-level sort and/or LIMIT. Note that any
* special work for recursive unions is the responsibility of
* plan_set_operations.
*/
current_rel = plan_set_operations(root);
/*
* We should not need to call preprocess_targetlist, since we must be
* in a SELECT query node. Instead, use the processed_tlist returned
* by plan_set_operations (since this tells whether it returned any
* resjunk columns!), and transfer any sort key information from the
* original tlist.
*/
Assert(parse->commandType == CMD_SELECT);
/* for safety, copy processed_tlist instead of modifying in-place */
root->processed_tlist =
postprocess_setop_tlist(copyObject(root->processed_tlist),
parse->targetList);
/* Also extract the PathTarget form of the setop result tlist */
final_target = current_rel->cheapest_total_path->pathtarget;
/* And check whether it's parallel safe */
final_target_parallel_safe =
is_parallel_safe(root, (Node *) final_target->exprs);
/* The setop result tlist couldn't contain any SRFs */
Assert(!parse->hasTargetSRFs);
final_targets = final_targets_contain_srfs = NIL;
/*
* Can't handle FOR [KEY] UPDATE/SHARE here (parser should have
* checked already, but let's make sure).
*/
if (parse->rowMarks)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
/*------
translator: %s is a SQL row locking clause such as FOR UPDATE */
errmsg("%s is not allowed with UNION/INTERSECT/EXCEPT",
LCS_asString(linitial_node(RowMarkClause,
parse->rowMarks)->strength))));
/*
* Calculate pathkeys that represent result ordering requirements
*/
Assert(parse->distinctClause == NIL);
root->sort_pathkeys = make_pathkeys_for_sortclauses(root,
parse->sortClause,
root->processed_tlist);
}
else
{
/* No set operations, do regular planning */
PathTarget *sort_input_target;
List *sort_input_targets;
List *sort_input_targets_contain_srfs;
bool sort_input_target_parallel_safe;
PathTarget *grouping_target;
List *grouping_targets;
List *grouping_targets_contain_srfs;
bool grouping_target_parallel_safe;
PathTarget *scanjoin_target;
List *scanjoin_targets;
List *scanjoin_targets_contain_srfs;
bool scanjoin_target_parallel_safe;
bool scanjoin_target_same_exprs;
bool have_grouping;
WindowFuncLists *wflists = NULL;
List *activeWindows = NIL;
grouping_sets_data *gset_data = NULL;
standard_qp_extra qp_extra;
/* A recursive query should always have setOperations */
Assert(!root->hasRecursion);
/* Preprocess grouping sets and GROUP BY clause, if any */
if (parse->groupingSets)
{
gset_data = preprocess_grouping_sets(root);
}
else
{
/* Preprocess regular GROUP BY clause, if any */
if (parse->groupClause)
parse->groupClause = preprocess_groupclause(root, NIL);
}
/*
* Preprocess targetlist. Note that much of the remaining planning
* work will be done with the PathTarget representation of tlists, but
* we must also maintain the full representation of the final tlist so
* that we can transfer its decoration (resnames etc) to the topmost
* tlist of the finished Plan. This is kept in processed_tlist.
*/
preprocess_targetlist(root);
/*
* Mark all the aggregates with resolved aggtranstypes, and detect
* aggregates that are duplicates or can share transition state. We
* must do this before slicing and dicing the tlist into various
* pathtargets, else some copies of the Aggref nodes might escape
* being marked.
*/
if (parse->hasAggs)
{
preprocess_aggrefs(root, (Node *) root->processed_tlist);
preprocess_aggrefs(root, (Node *) parse->havingQual);
}
/*
* Locate any window functions in the tlist. (We don't need to look
* anywhere else, since expressions used in ORDER BY will be in there
* too.) Note that they could all have been eliminated by constant
* folding, in which case we don't need to do any more work.
*/
if (parse->hasWindowFuncs)
{
wflists = find_window_functions((Node *) root->processed_tlist,
list_length(parse->windowClause));
if (wflists->numWindowFuncs > 0)
activeWindows = select_active_windows(root, wflists);
else
parse->hasWindowFuncs = false;
}
/*
* Preprocess MIN/MAX aggregates, if any. Note: be careful about
* adding logic between here and the query_planner() call. Anything
* that is needed in MIN/MAX-optimizable cases will have to be
* duplicated in planagg.c.
*/
if (parse->hasAggs)
preprocess_minmax_aggregates(root);
/*
* Figure out whether there's a hard limit on the number of rows that
* query_planner's result subplan needs to return. Even if we know a
* hard limit overall, it doesn't apply if the query has any
* grouping/aggregation operations, or SRFs in the tlist.
*/
if (parse->groupClause ||
parse->groupingSets ||
parse->distinctClause ||
parse->hasAggs ||
parse->hasWindowFuncs ||
parse->hasTargetSRFs ||
root->hasHavingQual)
root->limit_tuples = -1.0;
else
root->limit_tuples = limit_tuples;
/* Set up data needed by standard_qp_callback */
qp_extra.activeWindows = activeWindows;
qp_extra.groupClause = (gset_data
? (gset_data->rollups ? linitial_node(RollupData, gset_data->rollups)->groupClause : NIL)
: parse->groupClause);
/*
* Generate the best unsorted and presorted paths for the scan/join
* portion of this Query, ie the processing represented by the
* FROM/WHERE clauses. (Note there may not be any presorted paths.)
* We also generate (in standard_qp_callback) pathkey representations
* of the query's sort clause, distinct clause, etc.
*/
current_rel = query_planner(root, standard_qp_callback, &qp_extra);
/*
* Convert the query's result tlist into PathTarget format.
*
* Note: this cannot be done before query_planner() has performed
* appendrel expansion, because that might add resjunk entries to
* root->processed_tlist. Waiting till afterwards is also helpful
* because the target width estimates can use per-Var width numbers
* that were obtained within query_planner().
*/
final_target = create_pathtarget(root, root->processed_tlist);
final_target_parallel_safe =
is_parallel_safe(root, (Node *) final_target->exprs);
/*
* If ORDER BY was given, consider whether we should use a post-sort
* projection, and compute the adjusted target for preceding steps if
* so.
*/
if (parse->sortClause)
{
sort_input_target = make_sort_input_target(root,
final_target,
&have_postponed_srfs);
sort_input_target_parallel_safe =
is_parallel_safe(root, (Node *) sort_input_target->exprs);
}
else
{
sort_input_target = final_target;
sort_input_target_parallel_safe = final_target_parallel_safe;
}
/*
* If we have window functions to deal with, the output from any
* grouping step needs to be what the window functions want;
* otherwise, it should be sort_input_target.
*/
if (activeWindows)
{
grouping_target = make_window_input_target(root,
final_target,
activeWindows);
grouping_target_parallel_safe =
is_parallel_safe(root, (Node *) grouping_target->exprs);
}
else
{
grouping_target = sort_input_target;
grouping_target_parallel_safe = sort_input_target_parallel_safe;
}
/*
* If we have grouping or aggregation to do, the topmost scan/join
* plan node must emit what the grouping step wants; otherwise, it
* should emit grouping_target.
*/
have_grouping = (parse->groupClause || parse->groupingSets ||
parse->hasAggs || root->hasHavingQual);
if (have_grouping)
{
scanjoin_target = make_group_input_target(root, final_target);
scanjoin_target_parallel_safe =
is_parallel_safe(root, (Node *) scanjoin_target->exprs);
}
else
{
scanjoin_target = grouping_target;
scanjoin_target_parallel_safe = grouping_target_parallel_safe;
}
/*
* If there are any SRFs in the targetlist, we must separate each of
* these PathTargets into SRF-computing and SRF-free targets. Replace
* each of the named targets with a SRF-free version, and remember the
* list of additional projection steps we need to add afterwards.
*/
if (parse->hasTargetSRFs)
{
/* final_target doesn't recompute any SRFs in sort_input_target */
split_pathtarget_at_srfs(root, final_target, sort_input_target,
&final_targets,
&final_targets_contain_srfs);
final_target = linitial_node(PathTarget, final_targets);
Assert(!linitial_int(final_targets_contain_srfs));
/* likewise for sort_input_target vs. grouping_target */
split_pathtarget_at_srfs(root, sort_input_target, grouping_target,
&sort_input_targets,
&sort_input_targets_contain_srfs);
sort_input_target = linitial_node(PathTarget, sort_input_targets);
Assert(!linitial_int(sort_input_targets_contain_srfs));
/* likewise for grouping_target vs. scanjoin_target */
split_pathtarget_at_srfs(root, grouping_target, scanjoin_target,
&grouping_targets,
&grouping_targets_contain_srfs);
grouping_target = linitial_node(PathTarget, grouping_targets);
Assert(!linitial_int(grouping_targets_contain_srfs));
/* scanjoin_target will not have any SRFs precomputed for it */
split_pathtarget_at_srfs(root, scanjoin_target, NULL,
&scanjoin_targets,
&scanjoin_targets_contain_srfs);
scanjoin_target = linitial_node(PathTarget, scanjoin_targets);
Assert(!linitial_int(scanjoin_targets_contain_srfs));
}
else
{
/* initialize lists; for most of these, dummy values are OK */
final_targets = final_targets_contain_srfs = NIL;
sort_input_targets = sort_input_targets_contain_srfs = NIL;
grouping_targets = grouping_targets_contain_srfs = NIL;
scanjoin_targets = list_make1(scanjoin_target);
scanjoin_targets_contain_srfs = NIL;
}
/* Apply scan/join target. */
scanjoin_target_same_exprs = list_length(scanjoin_targets) == 1
&& equal(scanjoin_target->exprs, current_rel->reltarget->exprs);
apply_scanjoin_target_to_paths(root, current_rel, scanjoin_targets,
scanjoin_targets_contain_srfs,
scanjoin_target_parallel_safe,
scanjoin_target_same_exprs);
/*
* Save the various upper-rel PathTargets we just computed into
* root->upper_targets[]. The core code doesn't use this, but it
* provides a convenient place for extensions to get at the info. For
* consistency, we save all the intermediate targets, even though some
* of the corresponding upperrels might not be needed for this query.
*/
root->upper_targets[UPPERREL_FINAL] = final_target;
root->upper_targets[UPPERREL_ORDERED] = final_target;
root->upper_targets[UPPERREL_DISTINCT] = sort_input_target;
root->upper_targets[UPPERREL_WINDOW] = sort_input_target;
root->upper_targets[UPPERREL_GROUP_AGG] = grouping_target;
/*
* If we have grouping and/or aggregation, consider ways to implement
* that. We build a new upperrel representing the output of this
* phase.
*/
if (have_grouping)
{
current_rel = create_grouping_paths(root,
current_rel,
grouping_target,
grouping_target_parallel_safe,
gset_data);
/* Fix things up if grouping_target contains SRFs */
if (parse->hasTargetSRFs)
adjust_paths_for_srfs(root, current_rel,
grouping_targets,
grouping_targets_contain_srfs);
}
/*
* If we have window functions, consider ways to implement those. We
* build a new upperrel representing the output of this phase.
*/
if (activeWindows)
{
current_rel = create_window_paths(root,
current_rel,
grouping_target,
sort_input_target,
sort_input_target_parallel_safe,
wflists,
activeWindows);
/* Fix things up if sort_input_target contains SRFs */
if (parse->hasTargetSRFs)
adjust_paths_for_srfs(root, current_rel,
sort_input_targets,
sort_input_targets_contain_srfs);
}
/*
* If there is a DISTINCT clause, consider ways to implement that. We
* build a new upperrel representing the output of this phase.
*/
if (parse->distinctClause)
{
current_rel = create_distinct_paths(root,
current_rel);
}
} /* end of if (setOperations) */
/*
* If ORDER BY was given, consider ways to implement that, and generate a
* new upperrel containing only paths that emit the correct ordering and
* project the correct final_target. We can apply the original
* limit_tuples limit in sort costing here, but only if there are no
* postponed SRFs.
*/
if (parse->sortClause)
{
current_rel = create_ordered_paths(root,
current_rel,
final_target,
final_target_parallel_safe,
have_postponed_srfs ? -1.0 :
limit_tuples);
/* Fix things up if final_target contains SRFs */
if (parse->hasTargetSRFs)
adjust_paths_for_srfs(root, current_rel,
final_targets,
final_targets_contain_srfs);
}
/*
* Now we are prepared to build the final-output upperrel.
*/
final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL);
/*
* If the input rel is marked consider_parallel and there's nothing that's
* not parallel-safe in the LIMIT clause, then the final_rel can be marked
* consider_parallel as well. Note that if the query has rowMarks or is
* not a SELECT, consider_parallel will be false for every relation in the
* query.
*/
if (current_rel->consider_parallel &&
is_parallel_safe(root, parse->limitOffset) &&
is_parallel_safe(root, parse->limitCount))
final_rel->consider_parallel = true;
/*
* If the current_rel belongs to a single FDW, so does the final_rel.
*/
final_rel->serverid = current_rel->serverid;
final_rel->userid = current_rel->userid;
final_rel->useridiscurrent = current_rel->useridiscurrent;
final_rel->fdwroutine = current_rel->fdwroutine;
/*
* Generate paths for the final_rel. Insert all surviving paths, with
* LockRows, Limit, and/or ModifyTable steps added if needed.
*/
foreach(lc, current_rel->pathlist)
{
Path *path = (Path *) lfirst(lc);
/*
* If there is a FOR [KEY] UPDATE/SHARE clause, add the LockRows node.
* (Note: we intentionally test parse->rowMarks not root->rowMarks
* here. If there are only non-locking rowmarks, they should be
* handled by the ModifyTable node instead. However, root->rowMarks
* is what goes into the LockRows node.)
*/
if (parse->rowMarks)
{
path = (Path *) create_lockrows_path(root, final_rel, path,
root->rowMarks,
assign_special_exec_param(root));
}
/*
* If there is a LIMIT/OFFSET clause, add the LIMIT node.
*/
if (limit_needed(parse))
{
path = (Path *) create_limit_path(root, final_rel, path,
parse->limitOffset,
parse->limitCount,
parse->limitOption,
offset_est, count_est);
}
/*
* If this is an INSERT/UPDATE/DELETE, add the ModifyTable node.
*/
if (parse->commandType != CMD_SELECT)
{
Index rootRelation;
List *resultRelations = NIL;
List *updateColnosLists = NIL;
List *withCheckOptionLists = NIL;
List *returningLists = NIL;
List *rowMarks;
if (bms_membership(root->all_result_relids) == BMS_MULTIPLE)
{
/* Inherited UPDATE/DELETE */
RelOptInfo *top_result_rel = find_base_rel(root,
parse->resultRelation);
int resultRelation = -1;
/* Add only leaf children to ModifyTable. */
while ((resultRelation = bms_next_member(root->leaf_result_relids,
resultRelation)) >= 0)
{
RelOptInfo *this_result_rel = find_base_rel(root,
resultRelation);
/*
* Also exclude any leaf rels that have turned dummy since
* being added to the list, for example, by being excluded
* by constraint exclusion.
*/
if (IS_DUMMY_REL(this_result_rel))
continue;
/* Build per-target-rel lists needed by ModifyTable */
resultRelations = lappend_int(resultRelations,
resultRelation);
if (parse->commandType == CMD_UPDATE)
{
List *update_colnos = root->update_colnos;
if (this_result_rel != top_result_rel)
update_colnos =
adjust_inherited_attnums_multilevel(root,
update_colnos,
this_result_rel->relid,
top_result_rel->relid);
updateColnosLists = lappend(updateColnosLists,
update_colnos);
}
if (parse->withCheckOptions)
{
List *withCheckOptions = parse->withCheckOptions;
if (this_result_rel != top_result_rel)
withCheckOptions = (List *)
adjust_appendrel_attrs_multilevel(root,
(Node *) withCheckOptions,
this_result_rel->relids,
top_result_rel->relids);
withCheckOptionLists = lappend(withCheckOptionLists,
withCheckOptions);
}
if (parse->returningList)
{
List *returningList = parse->returningList;
if (this_result_rel != top_result_rel)
returningList = (List *)
adjust_appendrel_attrs_multilevel(root,
(Node *) returningList,
this_result_rel->relids,
top_result_rel->relids);
returningLists = lappend(returningLists,
returningList);
}
}
if (resultRelations == NIL)
{
/*
* We managed to exclude every child rel, so generate a
* dummy one-relation plan using info for the top target
* rel (even though that may not be a leaf target).
* Although it's clear that no data will be updated or
* deleted, we still need to have a ModifyTable node so
* that any statement triggers will be executed. (This
* could be cleaner if we fixed nodeModifyTable.c to allow
* zero target relations, but that probably wouldn't be a
* net win.)
*/
resultRelations = list_make1_int(parse->resultRelation);
if (parse->commandType == CMD_UPDATE)
updateColnosLists = list_make1(root->update_colnos);
if (parse->withCheckOptions)
withCheckOptionLists = list_make1(parse->withCheckOptions);
if (parse->returningList)
returningLists = list_make1(parse->returningList);
}
}
else
{
/* Single-relation INSERT/UPDATE/DELETE. */
resultRelations = list_make1_int(parse->resultRelation);
if (parse->commandType == CMD_UPDATE)
updateColnosLists = list_make1(root->update_colnos);
if (parse->withCheckOptions)
withCheckOptionLists = list_make1(parse->withCheckOptions);
if (parse->returningList)
returningLists = list_make1(parse->returningList);
}
/*
* If target is a partition root table, we need to mark the
* ModifyTable node appropriately for that.
*/
if (rt_fetch(parse->resultRelation, parse->rtable)->relkind ==
RELKIND_PARTITIONED_TABLE)
rootRelation = parse->resultRelation;
else
rootRelation = 0;
/*
* If there was a FOR [KEY] UPDATE/SHARE clause, the LockRows node
* will have dealt with fetching non-locked marked rows, else we
* need to have ModifyTable do that.
*/
if (parse->rowMarks)
rowMarks = NIL;
else
rowMarks = root->rowMarks;
path = (Path *)
create_modifytable_path(root, final_rel,
path,
parse->commandType,
parse->canSetTag,
parse->resultRelation,
rootRelation,
root->partColsUpdated,
resultRelations,
updateColnosLists,
withCheckOptionLists,
returningLists,
rowMarks,
parse->onConflict,
assign_special_exec_param(root));
}
/* And shove it into final_rel */
add_path(final_rel, path);
}
/*
* Generate partial paths for final_rel, too, if outer query levels might
* be able to make use of them.
*/
if (final_rel->consider_parallel && root->query_level > 1 &&
!limit_needed(parse))
{
Assert(!parse->rowMarks && parse->commandType == CMD_SELECT);
foreach(lc, current_rel->partial_pathlist)
{
Path *partial_path = (Path *) lfirst(lc);
add_partial_path(final_rel, partial_path);
}
}
extra.limit_needed = limit_needed(parse);
extra.limit_tuples = limit_tuples;
extra.count_est = count_est;
extra.offset_est = offset_est;
/*
* If there is an FDW that's responsible for all baserels of the query,
* let it consider adding ForeignPaths.
*/
if (final_rel->fdwroutine &&
final_rel->fdwroutine->GetForeignUpperPaths)
final_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_FINAL,
current_rel, final_rel,
&extra);
/* Let extensions possibly add some more paths */
if (create_upper_paths_hook)
(*create_upper_paths_hook) (root, UPPERREL_FINAL,
current_rel, final_rel, &extra);
/* Note: currently, we leave it to callers to do set_cheapest() */
}
/*
* Do preprocessing for groupingSets clause and related data. This handles the
* preliminary steps of expanding the grouping sets, organizing them into lists
* of rollups, and preparing annotations which will later be filled in with
* size estimates.
*/
static grouping_sets_data *
preprocess_grouping_sets(PlannerInfo *root)
{
Query *parse = root->parse;
List *sets;
int maxref = 0;
ListCell *lc;
ListCell *lc_set;
grouping_sets_data *gd = palloc0(sizeof(grouping_sets_data));
parse->groupingSets = expand_grouping_sets(parse->groupingSets, parse->groupDistinct, -1);
gd->any_hashable = false;
gd->unhashable_refs = NULL;
gd->unsortable_refs = NULL;
gd->unsortable_sets = NIL;
if (parse->groupClause)
{
ListCell *lc;
foreach(lc, parse->groupClause)
{
SortGroupClause *gc = lfirst_node(SortGroupClause, lc);
Index ref = gc->tleSortGroupRef;
if (ref > maxref)
maxref = ref;
if (!gc->hashable)
gd->unhashable_refs = bms_add_member(gd->unhashable_refs, ref);
if (!OidIsValid(gc->sortop))
gd->unsortable_refs = bms_add_member(gd->unsortable_refs, ref);
}
}
/* Allocate workspace array for remapping */
gd->tleref_to_colnum_map = (int *) palloc((maxref + 1) * sizeof(int));
/*
* If we have any unsortable sets, we must extract them before trying to
* prepare rollups. Unsortable sets don't go through
* reorder_grouping_sets, so we must apply the GroupingSetData annotation
* here.
*/
if (!bms_is_empty(gd->unsortable_refs))
{
List *sortable_sets = NIL;
foreach(lc, parse->groupingSets)
{
List *gset = (List *) lfirst(lc);
if (bms_overlap_list(gd->unsortable_refs, gset))
{
GroupingSetData *gs = makeNode(GroupingSetData);
gs->set = gset;
gd->unsortable_sets = lappend(gd->unsortable_sets, gs);
/*
* We must enforce here that an unsortable set is hashable;
* later code assumes this. Parse analysis only checks that
* every individual column is either hashable or sortable.
*
* Note that passing this test doesn't guarantee we can
* generate a plan; there might be other showstoppers.
*/
if (bms_overlap_list(gd->unhashable_refs, gset))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("could not implement GROUP BY"),
errdetail("Some of the datatypes only support hashing, while others only support sorting.")));
}
else
sortable_sets = lappend(sortable_sets, gset);
}
if (sortable_sets)
sets = extract_rollup_sets(sortable_sets);
else
sets = NIL;
}
else
sets = extract_rollup_sets(parse->groupingSets);
foreach(lc_set, sets)
{
List *current_sets = (List *) lfirst(lc_set);
RollupData *rollup = makeNode(RollupData);
GroupingSetData *gs;
/*
* Reorder the current list of grouping sets into correct prefix
* order. If only one aggregation pass is needed, try to make the
* list match the ORDER BY clause; if more than one pass is needed, we
* don't bother with that.
*
* Note that this reorders the sets from smallest-member-first to
* largest-member-first, and applies the GroupingSetData annotations,
* though the data will be filled in later.
*/
current_sets = reorder_grouping_sets(current_sets,
(list_length(sets) == 1
? parse->sortClause
: NIL));
/*
* Get the initial (and therefore largest) grouping set.
*/
gs = linitial_node(GroupingSetData, current_sets);
/*
* Order the groupClause appropriately. If the first grouping set is
* empty, then the groupClause must also be empty; otherwise we have
* to force the groupClause to match that grouping set's order.
*
* (The first grouping set can be empty even though parse->groupClause
* is not empty only if all non-empty grouping sets are unsortable.
* The groupClauses for hashed grouping sets are built later on.)
*/
if (gs->set)
rollup->groupClause = preprocess_groupclause(root, gs->set);
else
rollup->groupClause = NIL;
/*
* Is it hashable? We pretend empty sets are hashable even though we
* actually force them not to be hashed later. But don't bother if
* there's nothing but empty sets (since in that case we can't hash
* anything).
*/
if (gs->set &&
!bms_overlap_list(gd->unhashable_refs, gs->set))
{
rollup->hashable = true;
gd->any_hashable = true;
}
/*
* Now that we've pinned down an order for the groupClause for this
* list of grouping sets, we need to remap the entries in the grouping
* sets from sortgrouprefs to plain indices (0-based) into the
* groupClause for this collection of grouping sets. We keep the
* original form for later use, though.
*/
rollup->gsets = remap_to_groupclause_idx(rollup->groupClause,
current_sets,
gd->tleref_to_colnum_map);
rollup->gsets_data = current_sets;
gd->rollups = lappend(gd->rollups, rollup);
}
if (gd->unsortable_sets)
{
/*
* We have not yet pinned down a groupclause for this, but we will
* need index-based lists for estimation purposes. Construct
* hash_sets_idx based on the entire original groupclause for now.
*/
gd->hash_sets_idx = remap_to_groupclause_idx(parse->groupClause,
gd->unsortable_sets,
gd->tleref_to_colnum_map);
gd->any_hashable = true;
}
return gd;
}
/*
* Given a groupclause and a list of GroupingSetData, return equivalent sets
* (without annotation) mapped to indexes into the given groupclause.
*/
static List *
remap_to_groupclause_idx(List *groupClause,
List *gsets,
int *tleref_to_colnum_map)
{
int ref = 0;
List *result = NIL;
ListCell *lc;
foreach(lc, groupClause)
{
SortGroupClause *gc = lfirst_node(SortGroupClause, lc);
tleref_to_colnum_map[gc->tleSortGroupRef] = ref++;
}
foreach(lc, gsets)
{
List *set = NIL;
ListCell *lc2;
GroupingSetData *gs = lfirst_node(GroupingSetData, lc);
foreach(lc2, gs->set)
{
set = lappend_int(set, tleref_to_colnum_map[lfirst_int(lc2)]);
}
result = lappend(result, set);
}
return result;
}
/*
* preprocess_rowmarks - set up PlanRowMarks if needed
*/
static void
preprocess_rowmarks(PlannerInfo *root)
{
Query *parse = root->parse;
Bitmapset *rels;
List *prowmarks;
ListCell *l;
int i;
if (parse->rowMarks)
{
/*
* We've got trouble if FOR [KEY] UPDATE/SHARE appears inside
* grouping, since grouping renders a reference to individual tuple
* CTIDs invalid. This is also checked at parse time, but that's
* insufficient because of rule substitution, query pullup, etc.
*/
CheckSelectLocking(parse, linitial_node(RowMarkClause,
parse->rowMarks)->strength);
}
else
{
/*
* We only need rowmarks for UPDATE, DELETE, or FOR [KEY]
* UPDATE/SHARE.
*/
if (parse->commandType != CMD_UPDATE &&
parse->commandType != CMD_DELETE)
return;
}
/*
* We need to have rowmarks for all base relations except the target. We
* make a bitmapset of all base rels and then remove the items we don't
* need or have FOR [KEY] UPDATE/SHARE marks for.
*/
rels = get_relids_in_jointree((Node *) parse->jointree, false);
if (parse->resultRelation)
rels = bms_del_member(rels, parse->resultRelation);
/*
* Convert RowMarkClauses to PlanRowMark representation.
*/
prowmarks = NIL;
foreach(l, parse->rowMarks)
{
RowMarkClause *rc = lfirst_node(RowMarkClause, l);
RangeTblEntry *rte = rt_fetch(rc->rti, parse->rtable);
PlanRowMark *newrc;
/*
* Currently, it is syntactically impossible to have FOR UPDATE et al
* applied to an update/delete target rel. If that ever becomes
* possible, we should drop the target from the PlanRowMark list.
*/
Assert(rc->rti != parse->resultRelation);
/*
* Ignore RowMarkClauses for subqueries; they aren't real tables and
* can't support true locking. Subqueries that got flattened into the
* main query should be ignored completely. Any that didn't will get
* ROW_MARK_COPY items in the next loop.
*/
if (rte->rtekind != RTE_RELATION)
continue;
rels = bms_del_member(rels, rc->rti);
newrc = makeNode(PlanRowMark);
newrc->rti = newrc->prti = rc->rti;
newrc->rowmarkId = ++(root->glob->lastRowMarkId);
newrc->markType = select_rowmark_type(rte, rc->strength);
newrc->allMarkTypes = (1 << newrc->markType);
newrc->strength = rc->strength;
newrc->waitPolicy = rc->waitPolicy;
newrc->isParent = false;
prowmarks = lappend(prowmarks, newrc);
}
/*
* Now, add rowmarks for any non-target, non-locked base relations.
*/
i = 0;
foreach(l, parse->rtable)
{
RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
PlanRowMark *newrc;
i++;
if (!bms_is_member(i, rels))
continue;
newrc = makeNode(PlanRowMark);
newrc->rti = newrc->prti = i;
newrc->rowmarkId = ++(root->glob->lastRowMarkId);
newrc->markType = select_rowmark_type(rte, LCS_NONE);
newrc->allMarkTypes = (1 << newrc->markType);
newrc->strength = LCS_NONE;
newrc->waitPolicy = LockWaitBlock; /* doesn't matter */
newrc->isParent = false;
prowmarks = lappend(prowmarks, newrc);
}
root->rowMarks = prowmarks;
}
/*
* Select RowMarkType to use for a given table
*/
RowMarkType
select_rowmark_type(RangeTblEntry *rte, LockClauseStrength strength)
{
if (rte->rtekind != RTE_RELATION)
{
/* If it's not a table at all, use ROW_MARK_COPY */
return ROW_MARK_COPY;
}
else if (rte->relkind == RELKIND_FOREIGN_TABLE)
{
/* Let the FDW select the rowmark type, if it wants to */
FdwRoutine *fdwroutine = GetFdwRoutineByRelId(rte->relid);
if (fdwroutine->GetForeignRowMarkType != NULL)
return fdwroutine->GetForeignRowMarkType(rte, strength);
/* Otherwise, use ROW_MARK_COPY by default */
return ROW_MARK_COPY;
}
else
{
/* Regular table, apply the appropriate lock type */
switch (strength)
{
case LCS_NONE:
/*
* We don't need a tuple lock, only the ability to re-fetch
* the row.
*/
return ROW_MARK_REFERENCE;
break;
case LCS_FORKEYSHARE:
return ROW_MARK_KEYSHARE;
break;
case LCS_FORSHARE:
return ROW_MARK_SHARE;
break;
case LCS_FORNOKEYUPDATE:
return ROW_MARK_NOKEYEXCLUSIVE;
break;
case LCS_FORUPDATE:
return ROW_MARK_EXCLUSIVE;
break;
}
elog(ERROR, "unrecognized LockClauseStrength %d", (int) strength);
return ROW_MARK_EXCLUSIVE; /* keep compiler quiet */
}
}
/*
* preprocess_limit - do pre-estimation for LIMIT and/or OFFSET clauses
*
* We try to estimate the values of the LIMIT/OFFSET clauses, and pass the
* results back in *count_est and *offset_est. These variables are set to
* 0 if the corresponding clause is not present, and -1 if it's present
* but we couldn't estimate the value for it. (The "0" convention is OK
* for OFFSET but a little bit bogus for LIMIT: effectively we estimate
* LIMIT 0 as though it were LIMIT 1. But this is in line with the planner's
* usual practice of never estimating less than one row.) These values will
* be passed to create_limit_path, which see if you change this code.
*
* The return value is the suitably adjusted tuple_fraction to use for
* planning the query. This adjustment is not overridable, since it reflects
* plan actions that grouping_planner() will certainly take, not assumptions
* about context.
*/
static double
preprocess_limit(PlannerInfo *root, double tuple_fraction,
int64 *offset_est, int64 *count_est)
{
Query *parse = root->parse;
Node *est;
double limit_fraction;
/* Should not be called unless LIMIT or OFFSET */
Assert(parse->limitCount || parse->limitOffset);
/*
* Try to obtain the clause values. We use estimate_expression_value
* primarily because it can sometimes do something useful with Params.
*/
if (parse->limitCount)
{
est = estimate_expression_value(root, parse->limitCount);
if (est && IsA(est, Const))
{
if (((Const *) est)->constisnull)
{
/* NULL indicates LIMIT ALL, ie, no limit */
*count_est = 0; /* treat as not present */
}
else
{
*count_est = DatumGetInt64(((Const *) est)->constvalue);
if (*count_est <= 0)
*count_est = 1; /* force to at least 1 */
}
}
else
*count_est = -1; /* can't estimate */
}
else
*count_est = 0; /* not present */
if (parse->limitOffset)
{
est = estimate_expression_value(root, parse->limitOffset);
if (est && IsA(est, Const))
{
if (((Const *) est)->constisnull)
{
/* Treat NULL as no offset; the executor will too */
*offset_est = 0; /* treat as not present */
}
else
{
*offset_est = DatumGetInt64(((Const *) est)->constvalue);
if (*offset_est < 0)
*offset_est = 0; /* treat as not present */
}
}
else
*offset_est = -1; /* can't estimate */
}
else
*offset_est = 0; /* not present */
if (*count_est != 0)
{
/*
* A LIMIT clause limits the absolute number of tuples returned.
* However, if it's not a constant LIMIT then we have to guess; for
* lack of a better idea, assume 10% of the plan's result is wanted.
*/
if (*count_est < 0 || *offset_est < 0)
{
/* LIMIT or OFFSET is an expression ... punt ... */
limit_fraction = 0.10;
}
else
{
/* LIMIT (plus OFFSET, if any) is max number of tuples needed */
limit_fraction = (double) *count_est + (double) *offset_est;
}
/*
* If we have absolute limits from both caller and LIMIT, use the
* smaller value; likewise if they are both fractional. If one is
* fractional and the other absolute, we can't easily determine which
* is smaller, but we use the heuristic that the absolute will usually
* be smaller.
*/
if (tuple_fraction >= 1.0)
{
if (limit_fraction >= 1.0)
{
/* both absolute */
tuple_fraction = Min(tuple_fraction, limit_fraction);
}
else
{
/* caller absolute, limit fractional; use caller's value */
}
}
else if (tuple_fraction > 0.0)
{
if (limit_fraction >= 1.0)
{
/* caller fractional, limit absolute; use limit */
tuple_fraction = limit_fraction;
}
else
{
/* both fractional */
tuple_fraction = Min(tuple_fraction, limit_fraction);
}
}
else
{
/* no info from caller, just use limit */
tuple_fraction = limit_fraction;
}
}
else if (*offset_est != 0 && tuple_fraction > 0.0)
{
/*
* We have an OFFSET but no LIMIT. This acts entirely differently
* from the LIMIT case: here, we need to increase rather than decrease
* the caller's tuple_fraction, because the OFFSET acts to cause more
* tuples to be fetched instead of fewer. This only matters if we got
* a tuple_fraction > 0, however.
*
* As above, use 10% if OFFSET is present but unestimatable.
*/
if (*offset_est < 0)
limit_fraction = 0.10;
else
limit_fraction = (double) *offset_est;
/*
* If we have absolute counts from both caller and OFFSET, add them
* together; likewise if they are both fractional. If one is
* fractional and the other absolute, we want to take the larger, and
* we heuristically assume that's the fractional one.
*/
if (tuple_fraction >= 1.0)
{
if (limit_fraction >= 1.0)
{
/* both absolute, so add them together */
tuple_fraction += limit_fraction;
}
else
{
/* caller absolute, limit fractional; use limit */
tuple_fraction = limit_fraction;
}
}
else
{
if (limit_fraction >= 1.0)
{
/* caller fractional, limit absolute; use caller's value */
}
else
{
/* both fractional, so add them together */
tuple_fraction += limit_fraction;
if (tuple_fraction >= 1.0)
tuple_fraction = 0.0; /* assume fetch all */
}
}
}
return tuple_fraction;
}
/*
* limit_needed - do we actually need a Limit plan node?
*
* If we have constant-zero OFFSET and constant-null LIMIT, we can skip adding
* a Limit node. This is worth checking for because "OFFSET 0" is a common
* locution for an optimization fence. (Because other places in the planner
* merely check whether parse->limitOffset isn't NULL, it will still work as
* an optimization fence --- we're just suppressing unnecessary run-time
* overhead.)
*
* This might look like it could be merged into preprocess_limit, but there's
* a key distinction: here we need hard constants in OFFSET/LIMIT, whereas
* in preprocess_limit it's good enough to consider estimated values.
*/
bool
limit_needed(Query *parse)
{
Node *node;
node = parse->limitCount;
if (node)
{
if (IsA(node, Const))
{
/* NULL indicates LIMIT ALL, ie, no limit */
if (!((Const *) node)->constisnull)
return true; /* LIMIT with a constant value */
}
else
return true; /* non-constant LIMIT */
}
node = parse->limitOffset;
if (node)
{
if (IsA(node, Const))
{
/* Treat NULL as no offset; the executor would too */
if (!((Const *) node)->constisnull)
{
int64 offset = DatumGetInt64(((Const *) node)->constvalue);
if (offset != 0)
return true; /* OFFSET with a nonzero value */
}
}
else
return true; /* non-constant OFFSET */
}
return false; /* don't need a Limit plan node */
}
/*
* remove_useless_groupby_columns
* Remove any columns in the GROUP BY clause that are redundant due to
* being functionally dependent on other GROUP BY columns.
*
* Since some other DBMSes do not allow references to ungrouped columns, it's
* not unusual to find all columns listed in GROUP BY even though listing the
* primary-key columns would be sufficient. Deleting such excess columns
* avoids redundant sorting work, so it's worth doing.
*
* Relcache invalidations will ensure that cached plans become invalidated
* when the underlying index of the pkey constraint is dropped.
*
* Currently, we only make use of pkey constraints for this, however, we may
* wish to take this further in the future and also use unique constraints
* which have NOT NULL columns. In that case, plan invalidation will still
* work since relations will receive a relcache invalidation when a NOT NULL
* constraint is dropped.
*/
static void
remove_useless_groupby_columns(PlannerInfo *root)
{
Query *parse = root->parse;
Bitmapset **groupbyattnos;
Bitmapset **surplusvars;
ListCell *lc;
int relid;
/* No chance to do anything if there are less than two GROUP BY items */
if (list_length(parse->groupClause) < 2)
return;
/* Don't fiddle with the GROUP BY clause if the query has grouping sets */
if (parse->groupingSets)
return;
/*
* Scan the GROUP BY clause to find GROUP BY items that are simple Vars.
* Fill groupbyattnos[k] with a bitmapset of the column attnos of RTE k
* that are GROUP BY items.
*/
groupbyattnos = (Bitmapset **) palloc0(sizeof(Bitmapset *) *
(list_length(parse->rtable) + 1));
foreach(lc, parse->groupClause)
{
SortGroupClause *sgc = lfirst_node(SortGroupClause, lc);
TargetEntry *tle = get_sortgroupclause_tle(sgc, parse->targetList);
Var *var = (Var *) tle->expr;
/*
* Ignore non-Vars and Vars from other query levels.
*
* XXX in principle, stable expressions containing Vars could also be
* removed, if all the Vars are functionally dependent on other GROUP
* BY items. But it's not clear that such cases occur often enough to
* be worth troubling over.
*/
if (!IsA(var, Var) ||
var->varlevelsup > 0)
continue;
/* OK, remember we have this Var */
relid = var->varno;
Assert(relid <= list_length(parse->rtable));
groupbyattnos[relid] = bms_add_member(groupbyattnos[relid],
var->varattno - FirstLowInvalidHeapAttributeNumber);
}
/*
* Consider each relation and see if it is possible to remove some of its
* Vars from GROUP BY. For simplicity and speed, we do the actual removal
* in a separate pass. Here, we just fill surplusvars[k] with a bitmapset
* of the column attnos of RTE k that are removable GROUP BY items.
*/
surplusvars = NULL; /* don't allocate array unless required */
relid = 0;
foreach(lc, parse->rtable)
{
RangeTblEntry *rte = lfirst_node(RangeTblEntry, lc);
Bitmapset *relattnos;
Bitmapset *pkattnos;
Oid constraintOid;
relid++;
/* Only plain relations could have primary-key constraints */
if (rte->rtekind != RTE_RELATION)
continue;
/*
* We must skip inheritance parent tables as some of the child rels
* may cause duplicate rows. This cannot happen with partitioned
* tables, however.
*/
if (rte->inh && rte->relkind != RELKIND_PARTITIONED_TABLE)
continue;
/* Nothing to do unless this rel has multiple Vars in GROUP BY */
relattnos = groupbyattnos[relid];
if (bms_membership(relattnos) != BMS_MULTIPLE)
continue;
/*
* Can't remove any columns for this rel if there is no suitable
* (i.e., nondeferrable) primary key constraint.
*/
pkattnos = get_primary_key_attnos(rte->relid, false, &constraintOid);
if (pkattnos == NULL)
continue;
/*
* If the primary key is a proper subset of relattnos then we have
* some items in the GROUP BY that can be removed.
*/
if (bms_subset_compare(pkattnos, relattnos) == BMS_SUBSET1)
{
/*
* To easily remember whether we've found anything to do, we don't
* allocate the surplusvars[] array until we find something.
*/
if (surplusvars == NULL)
surplusvars = (Bitmapset **) palloc0(sizeof(Bitmapset *) *
(list_length(parse->rtable) + 1));
/* Remember the attnos of the removable columns */
surplusvars[relid] = bms_difference(relattnos, pkattnos);
}
}
/*
* If we found any surplus Vars, build a new GROUP BY clause without them.
* (Note: this may leave some TLEs with unreferenced ressortgroupref
* markings, but that's harmless.)
*/
if (surplusvars != NULL)
{
List *new_groupby = NIL;
foreach(lc, parse->groupClause)
{
SortGroupClause *sgc = lfirst_node(SortGroupClause, lc);
TargetEntry *tle = get_sortgroupclause_tle(sgc, parse->targetList);
Var *var = (Var *) tle->expr;
/*
* New list must include non-Vars, outer Vars, and anything not
* marked as surplus.
*/
if (!IsA(var, Var) ||
var->varlevelsup > 0 ||
!bms_is_member(var->varattno - FirstLowInvalidHeapAttributeNumber,
surplusvars[var->varno]))
new_groupby = lappend(new_groupby, sgc);
}
parse->groupClause = new_groupby;
}
}
/*
* preprocess_groupclause - do preparatory work on GROUP BY clause
*
* The idea here is to adjust the ordering of the GROUP BY elements
* (which in itself is semantically insignificant) to match ORDER BY,
* thereby allowing a single sort operation to both implement the ORDER BY
* requirement and set up for a Unique step that implements GROUP BY.
*
* In principle it might be interesting to consider other orderings of the
* GROUP BY elements, which could match the sort ordering of other
* possible plans (eg an indexscan) and thereby reduce cost. We don't
* bother with that, though. Hashed grouping will frequently win anyway.
*
* Note: we need no comparable processing of the distinctClause because
* the parser already enforced that that matches ORDER BY.
*
* For grouping sets, the order of items is instead forced to agree with that
* of the grouping set (and items not in the grouping set are skipped). The
* work of sorting the order of grouping set elements to match the ORDER BY if
* possible is done elsewhere.
*/
static List *
preprocess_groupclause(PlannerInfo *root, List *force)
{
Query *parse = root->parse;
List *new_groupclause = NIL;
bool partial_match;
ListCell *sl;
ListCell *gl;
/* For grouping sets, we need to force the ordering */
if (force)
{
foreach(sl, force)
{
Index ref = lfirst_int(sl);
SortGroupClause *cl = get_sortgroupref_clause(ref, parse->groupClause);
new_groupclause = lappend(new_groupclause, cl);
}
return new_groupclause;
}
/* If no ORDER BY, nothing useful to do here */
if (parse->sortClause == NIL)
return parse->groupClause;
/*
* Scan the ORDER BY clause and construct a list of matching GROUP BY
* items, but only as far as we can make a matching prefix.
*
* This code assumes that the sortClause contains no duplicate items.
*/
foreach(sl, parse->sortClause)
{
SortGroupClause *sc = lfirst_node(SortGroupClause, sl);
foreach(gl, parse->groupClause)
{
SortGroupClause *gc = lfirst_node(SortGroupClause, gl);
if (equal(gc, sc))
{
new_groupclause = lappend(new_groupclause, gc);
break;
}
}
if (gl == NULL)
break; /* no match, so stop scanning */
}
/* Did we match all of the ORDER BY list, or just some of it? */
partial_match = (sl != NULL);
/* If no match at all, no point in reordering GROUP BY */
if (new_groupclause == NIL)
return parse->groupClause;
/*
* Add any remaining GROUP BY items to the new list, but only if we were
* able to make a complete match. In other words, we only rearrange the
* GROUP BY list if the result is that one list is a prefix of the other
* --- otherwise there's no possibility of a common sort. Also, give up
* if there are any non-sortable GROUP BY items, since then there's no
* hope anyway.
*/
foreach(gl, parse->groupClause)
{
SortGroupClause *gc = lfirst_node(SortGroupClause, gl);
if (list_member_ptr(new_groupclause, gc))
continue; /* it matched an ORDER BY item */
if (partial_match)
return parse->groupClause; /* give up, no common sort possible */
if (!OidIsValid(gc->sortop))
return parse->groupClause; /* give up, GROUP BY can't be sorted */
new_groupclause = lappend(new_groupclause, gc);
}
/* Success --- install the rearranged GROUP BY list */
Assert(list_length(parse->groupClause) == list_length(new_groupclause));
return new_groupclause;
}
/*
* Extract lists of grouping sets that can be implemented using a single
* rollup-type aggregate pass each. Returns a list of lists of grouping sets.
*
* Input must be sorted with smallest sets first. Result has each sublist
* sorted with smallest sets first.
*
* We want to produce the absolute minimum possible number of lists here to
* avoid excess sorts. Fortunately, there is an algorithm for this; the problem
* of finding the minimal partition of a partially-ordered set into chains
* (which is what we need, taking the list of grouping sets as a poset ordered
* by set inclusion) can be mapped to the problem of finding the maximum
* cardinality matching on a bipartite graph, which is solvable in polynomial
* time with a worst case of no worse than O(n^2.5) and usually much
* better. Since our N is at most 4096, we don't need to consider fallbacks to
* heuristic or approximate methods. (Planning time for a 12-d cube is under
* half a second on my modest system even with optimization off and assertions
* on.)
*/
static List *
extract_rollup_sets(List *groupingSets)
{
int num_sets_raw = list_length(groupingSets);
int num_empty = 0;
int num_sets = 0; /* distinct sets */
int num_chains = 0;
List *result = NIL;
List **results;
List **orig_sets;
Bitmapset **set_masks;
int *chains;
short **adjacency;
short *adjacency_buf;
BipartiteMatchState *state;
int i;
int j;
int j_size;
ListCell *lc1 = list_head(groupingSets);
ListCell *lc;
/*
* Start by stripping out empty sets. The algorithm doesn't require this,
* but the planner currently needs all empty sets to be returned in the
* first list, so we strip them here and add them back after.
*/
while (lc1 && lfirst(lc1) == NIL)
{
++num_empty;
lc1 = lnext(groupingSets, lc1);
}
/* bail out now if it turns out that all we had were empty sets. */
if (!lc1)
return list_make1(groupingSets);
/*----------
* We don't strictly need to remove duplicate sets here, but if we don't,
* they tend to become scattered through the result, which is a bit
* confusing (and irritating if we ever decide to optimize them out).
* So we remove them here and add them back after.
*
* For each non-duplicate set, we fill in the following:
*
* orig_sets[i] = list of the original set lists
* set_masks[i] = bitmapset for testing inclusion
* adjacency[i] = array [n, v1, v2, ... vn] of adjacency indices
*
* chains[i] will be the result group this set is assigned to.
*
* We index all of these from 1 rather than 0 because it is convenient
* to leave 0 free for the NIL node in the graph algorithm.
*----------
*/
orig_sets = palloc0((num_sets_raw + 1) * sizeof(List *));
set_masks = palloc0((num_sets_raw + 1) * sizeof(Bitmapset *));
adjacency = palloc0((num_sets_raw + 1) * sizeof(short *));
adjacency_buf = palloc((num_sets_raw + 1) * sizeof(short));
j_size = 0;
j = 0;
i = 1;
for_each_cell(lc, groupingSets, lc1)
{
List *candidate = (List *) lfirst(lc);
Bitmapset *candidate_set = NULL;
ListCell *lc2;
int dup_of = 0;
foreach(lc2, candidate)
{
candidate_set = bms_add_member(candidate_set, lfirst_int(lc2));
}
/* we can only be a dup if we're the same length as a previous set */
if (j_size == list_length(candidate))
{
int k;
for (k = j; k < i; ++k)
{
if (bms_equal(set_masks[k], candidate_set))
{
dup_of = k;
break;
}
}
}
else if (j_size < list_length(candidate))
{
j_size = list_length(candidate);
j = i;
}
if (dup_of > 0)
{
orig_sets[dup_of] = lappend(orig_sets[dup_of], candidate);
bms_free(candidate_set);
}
else
{
int k;
int n_adj = 0;
orig_sets[i] = list_make1(candidate);
set_masks[i] = candidate_set;
/* fill in adjacency list; no need to compare equal-size sets */
for (k = j - 1; k > 0; --k)
{
if (bms_is_subset(set_masks[k], candidate_set))
adjacency_buf[++n_adj] = k;
}
if (n_adj > 0)
{
adjacency_buf[0] = n_adj;
adjacency[i] = palloc((n_adj + 1) * sizeof(short));
memcpy(adjacency[i], adjacency_buf, (n_adj + 1) * sizeof(short));
}
else
adjacency[i] = NULL;
++i;
}
}
num_sets = i - 1;
/*
* Apply the graph matching algorithm to do the work.
*/
state = BipartiteMatch(num_sets, num_sets, adjacency);
/*
* Now, the state->pair* fields have the info we need to assign sets to
* chains. Two sets (u,v) belong to the same chain if pair_uv[u] = v or
* pair_vu[v] = u (both will be true, but we check both so that we can do
* it in one pass)
*/
chains = palloc0((num_sets + 1) * sizeof(int));
for (i = 1; i <= num_sets; ++i)
{
int u = state->pair_vu[i];
int v = state->pair_uv[i];
if (u > 0 && u < i)
chains[i] = chains[u];
else if (v > 0 && v < i)
chains[i] = chains[v];
else
chains[i] = ++num_chains;
}
/* build result lists. */
results = palloc0((num_chains + 1) * sizeof(List *));
for (i = 1; i <= num_sets; ++i)
{
int c = chains[i];
Assert(c > 0);
results[c] = list_concat(results[c], orig_sets[i]);
}
/* push any empty sets back on the first list. */
while (num_empty-- > 0)
results[1] = lcons(NIL, results[1]);
/* make result list */
for (i = 1; i <= num_chains; ++i)
result = lappend(result, results[i]);
/*
* Free all the things.
*
* (This is over-fussy for small sets but for large sets we could have
* tied up a nontrivial amount of memory.)
*/
BipartiteMatchFree(state);
pfree(results);
pfree(chains);
for (i = 1; i <= num_sets; ++i)
if (adjacency[i])
pfree(adjacency[i]);
pfree(adjacency);
pfree(adjacency_buf);
pfree(orig_sets);
for (i = 1; i <= num_sets; ++i)
bms_free(set_masks[i]);
pfree(set_masks);
return result;
}
/*
* Reorder the elements of a list of grouping sets such that they have correct
* prefix relationships. Also inserts the GroupingSetData annotations.
*
* The input must be ordered with smallest sets first; the result is returned
* with largest sets first. Note that the result shares no list substructure
* with the input, so it's safe for the caller to modify it later.
*
* If we're passed in a sortclause, we follow its order of columns to the
* extent possible, to minimize the chance that we add unnecessary sorts.
* (We're trying here to ensure that GROUPING SETS ((a,b,c),(c)) ORDER BY c,b,a
* gets implemented in one pass.)
*/
static List *
reorder_grouping_sets(List *groupingsets, List *sortclause)
{
ListCell *lc;
List *previous = NIL;
List *result = NIL;
foreach(lc, groupingsets)
{
List *candidate = (List *) lfirst(lc);
List *new_elems = list_difference_int(candidate, previous);
GroupingSetData *gs = makeNode(GroupingSetData);
while (list_length(sortclause) > list_length(previous) &&
list_length(new_elems) > 0)
{
SortGroupClause *sc = list_nth(sortclause, list_length(previous));
int ref = sc->tleSortGroupRef;
if (list_member_int(new_elems, ref))
{
previous = lappend_int(previous, ref);
new_elems = list_delete_int(new_elems, ref);
}
else
{
/* diverged from the sortclause; give up on it */
sortclause = NIL;
break;
}
}
previous = list_concat(previous, new_elems);
gs->set = list_copy(previous);
result = lcons(gs, result);
}
list_free(previous);
return result;
}
/*
* Compute query_pathkeys and other pathkeys during plan generation
*/
static void
standard_qp_callback(PlannerInfo *root, void *extra)
{
Query *parse = root->parse;
standard_qp_extra *qp_extra = (standard_qp_extra *) extra;
List *tlist = root->processed_tlist;
List *activeWindows = qp_extra->activeWindows;
/*
* Calculate pathkeys that represent grouping/ordering requirements. The
* sortClause is certainly sort-able, but GROUP BY and DISTINCT might not
* be, in which case we just leave their pathkeys empty.
*/
if (qp_extra->groupClause &&
grouping_is_sortable(qp_extra->groupClause))
root->group_pathkeys =
make_pathkeys_for_sortclauses(root,
qp_extra->groupClause,
tlist);
else
root->group_pathkeys = NIL;
/* We consider only the first (bottom) window in pathkeys logic */
if (activeWindows != NIL)
{
WindowClause *wc = linitial_node(WindowClause, activeWindows);
root->window_pathkeys = make_pathkeys_for_window(root,
wc,
tlist);
}
else
root->window_pathkeys = NIL;
if (parse->distinctClause &&
grouping_is_sortable(parse->distinctClause))
root->distinct_pathkeys =
make_pathkeys_for_sortclauses(root,
parse->distinctClause,
tlist);
else
root->distinct_pathkeys = NIL;
root->sort_pathkeys =
make_pathkeys_for_sortclauses(root,
parse->sortClause,
tlist);
/*
* Figure out whether we want a sorted result from query_planner.
*
* If we have a sortable GROUP BY clause, then we want a result sorted
* properly for grouping. Otherwise, if we have window functions to
* evaluate, we try to sort for the first window. Otherwise, if there's a
* sortable DISTINCT clause that's more rigorous than the ORDER BY clause,
* we try to produce output that's sufficiently well sorted for the
* DISTINCT. Otherwise, if there is an ORDER BY clause, we want to sort
* by the ORDER BY clause.
*
* Note: if we have both ORDER BY and GROUP BY, and ORDER BY is a superset
* of GROUP BY, it would be tempting to request sort by ORDER BY --- but
* that might just leave us failing to exploit an available sort order at
* all. Needs more thought. The choice for DISTINCT versus ORDER BY is
* much easier, since we know that the parser ensured that one is a
* superset of the other.
*/
if (root->group_pathkeys)
root->query_pathkeys = root->group_pathkeys;
else if (root->window_pathkeys)
root->query_pathkeys = root->window_pathkeys;
else if (list_length(root->distinct_pathkeys) >
list_length(root->sort_pathkeys))
root->query_pathkeys = root->distinct_pathkeys;
else if (root->sort_pathkeys)
root->query_pathkeys = root->sort_pathkeys;
else
root->query_pathkeys = NIL;
}
/*
* Estimate number of groups produced by grouping clauses (1 if not grouping)
*
* path_rows: number of output rows from scan/join step
* gd: grouping sets data including list of grouping sets and their clauses
* target_list: target list containing group clause references
*
* If doing grouping sets, we also annotate the gsets data with the estimates
* for each set and each individual rollup list, with a view to later
* determining whether some combination of them could be hashed instead.
*/
static double
get_number_of_groups(PlannerInfo *root,
double path_rows,
grouping_sets_data *gd,
List *target_list)
{
Query *parse = root->parse;
double dNumGroups;
if (parse->groupClause)
{
List *groupExprs;
if (parse->groupingSets)
{
/* Add up the estimates for each grouping set */
ListCell *lc;
ListCell *lc2;
Assert(gd); /* keep Coverity happy */
dNumGroups = 0;
foreach(lc, gd->rollups)
{
RollupData *rollup = lfirst_node(RollupData, lc);
ListCell *lc;
groupExprs = get_sortgrouplist_exprs(rollup->groupClause,
target_list);
rollup->numGroups = 0.0;
forboth(lc, rollup->gsets, lc2, rollup->gsets_data)
{
List *gset = (List *) lfirst(lc);
GroupingSetData *gs = lfirst_node(GroupingSetData, lc2);
double numGroups = estimate_num_groups(root,
groupExprs,
path_rows,
&gset,
NULL);
gs->numGroups = numGroups;
rollup->numGroups += numGroups;
}
dNumGroups += rollup->numGroups;
}
if (gd->hash_sets_idx)
{
ListCell *lc;
gd->dNumHashGroups = 0;
groupExprs = get_sortgrouplist_exprs(parse->groupClause,
target_list);
forboth(lc, gd->hash_sets_idx, lc2, gd->unsortable_sets)
{
List *gset = (List *) lfirst(lc);
GroupingSetData *gs = lfirst_node(GroupingSetData, lc2);
double numGroups = estimate_num_groups(root,
groupExprs,
path_rows,
&gset,
NULL);
gs->numGroups = numGroups;
gd->dNumHashGroups += numGroups;
}
dNumGroups += gd->dNumHashGroups;
}
}
else
{
/* Plain GROUP BY */
groupExprs = get_sortgrouplist_exprs(parse->groupClause,
target_list);
dNumGroups = estimate_num_groups(root, groupExprs, path_rows,
NULL, NULL);
}
}
else if (parse->groupingSets)
{
/* Empty grouping sets ... one result row for each one */
dNumGroups = list_length(parse->groupingSets);
}
else if (parse->hasAggs || root->hasHavingQual)
{
/* Plain aggregation, one result row */
dNumGroups = 1;
}
else
{
/* Not grouping */
dNumGroups = 1;
}
return dNumGroups;
}
/*
* create_grouping_paths
*
* Build a new upperrel containing Paths for grouping and/or aggregation.
* Along the way, we also build an upperrel for Paths which are partially
* grouped and/or aggregated. A partially grouped and/or aggregated path
* needs a FinalizeAggregate node to complete the aggregation. Currently,
* the only partially grouped paths we build are also partial paths; that
* is, they need a Gather and then a FinalizeAggregate.
*
* input_rel: contains the source-data Paths
* target: the pathtarget for the result Paths to compute
* gd: grouping sets data including list of grouping sets and their clauses
*
* Note: all Paths in input_rel are expected to return the target computed
* by make_group_input_target.
*/
static RelOptInfo *
create_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
PathTarget *target,
bool target_parallel_safe,
grouping_sets_data *gd)
{
Query *parse = root->parse;
RelOptInfo *grouped_rel;
RelOptInfo *partially_grouped_rel;
AggClauseCosts agg_costs;
MemSet(&agg_costs, 0, sizeof(AggClauseCosts));
get_agg_clause_costs(root, AGGSPLIT_SIMPLE, &agg_costs);
/*
* Create grouping relation to hold fully aggregated grouping and/or
* aggregation paths.
*/
grouped_rel = make_grouping_rel(root, input_rel, target,
target_parallel_safe, parse->havingQual);
/*
* Create either paths for a degenerate grouping or paths for ordinary
* grouping, as appropriate.
*/
if (is_degenerate_grouping(root))
create_degenerate_grouping_paths(root, input_rel, grouped_rel);
else
{
int flags = 0;
GroupPathExtraData extra;
/*
* Determine whether it's possible to perform sort-based
* implementations of grouping. (Note that if groupClause is empty,
* grouping_is_sortable() is trivially true, and all the
* pathkeys_contained_in() tests will succeed too, so that we'll
* consider every surviving input path.)
*
* If we have grouping sets, we might be able to sort some but not all
* of them; in this case, we need can_sort to be true as long as we
* must consider any sorted-input plan.
*/
if ((gd && gd->rollups != NIL)
|| grouping_is_sortable(parse->groupClause))
flags |= GROUPING_CAN_USE_SORT;
/*
* Determine whether we should consider hash-based implementations of
* grouping.
*
* Hashed aggregation only applies if we're grouping. If we have
* grouping sets, some groups might be hashable but others not; in
* this case we set can_hash true as long as there is nothing globally
* preventing us from hashing (and we should therefore consider plans
* with hashes).
*
* Executor doesn't support hashed aggregation with DISTINCT or ORDER
* BY aggregates. (Doing so would imply storing *all* the input
* values in the hash table, and/or running many sorts in parallel,
* either of which seems like a certain loser.) We similarly don't
* support ordered-set aggregates in hashed aggregation, but that case
* is also included in the numOrderedAggs count.
*
* Note: grouping_is_hashable() is much more expensive to check than
* the other gating conditions, so we want to do it last.
*/
if ((parse->groupClause != NIL &&
root->numOrderedAggs == 0 &&
(gd ? gd->any_hashable : grouping_is_hashable(parse->groupClause))))
flags |= GROUPING_CAN_USE_HASH;
/*
* Determine whether partial aggregation is possible.
*/
if (can_partial_agg(root))
flags |= GROUPING_CAN_PARTIAL_AGG;
extra.flags = flags;
extra.target_parallel_safe = target_parallel_safe;
extra.havingQual = parse->havingQual;
extra.targetList = parse->targetList;
extra.partial_costs_set = false;
/*
* Determine whether partitionwise aggregation is in theory possible.
* It can be disabled by the user, and for now, we don't try to
* support grouping sets. create_ordinary_grouping_paths() will check
* additional conditions, such as whether input_rel is partitioned.
*/
if (enable_partitionwise_aggregate && !parse->groupingSets)
extra.patype = PARTITIONWISE_AGGREGATE_FULL;
else
extra.patype = PARTITIONWISE_AGGREGATE_NONE;
create_ordinary_grouping_paths(root, input_rel, grouped_rel,
&agg_costs, gd, &extra,
&partially_grouped_rel);
}
set_cheapest(grouped_rel);
return grouped_rel;
}
/*
* make_grouping_rel
*
* Create a new grouping rel and set basic properties.
*
* input_rel represents the underlying scan/join relation.
* target is the output expected from the grouping relation.
*/
static RelOptInfo *
make_grouping_rel(PlannerInfo *root, RelOptInfo *input_rel,
PathTarget *target, bool target_parallel_safe,
Node *havingQual)
{
RelOptInfo *grouped_rel;
if (IS_OTHER_REL(input_rel))
{
grouped_rel = fetch_upper_rel(root, UPPERREL_GROUP_AGG,
input_rel->relids);
grouped_rel->reloptkind = RELOPT_OTHER_UPPER_REL;
}
else
{
/*
* By tradition, the relids set for the main grouping relation is
* NULL. (This could be changed, but might require adjustments
* elsewhere.)
*/
grouped_rel = fetch_upper_rel(root, UPPERREL_GROUP_AGG, NULL);
}
/* Set target. */
grouped_rel->reltarget = target;
/*
* If the input relation is not parallel-safe, then the grouped relation
* can't be parallel-safe, either. Otherwise, it's parallel-safe if the
* target list and HAVING quals are parallel-safe.
*/
if (input_rel->consider_parallel && target_parallel_safe &&
is_parallel_safe(root, (Node *) havingQual))
grouped_rel->consider_parallel = true;
/*
* If the input rel belongs to a single FDW, so does the grouped rel.
*/
grouped_rel->serverid = input_rel->serverid;
grouped_rel->userid = input_rel->userid;
grouped_rel->useridiscurrent = input_rel->useridiscurrent;
grouped_rel->fdwroutine = input_rel->fdwroutine;
return grouped_rel;
}
/*
* is_degenerate_grouping
*
* A degenerate grouping is one in which the query has a HAVING qual and/or
* grouping sets, but no aggregates and no GROUP BY (which implies that the
* grouping sets are all empty).
*/
static bool
is_degenerate_grouping(PlannerInfo *root)
{
Query *parse = root->parse;
return (root->hasHavingQual || parse->groupingSets) &&
!parse->hasAggs && parse->groupClause == NIL;
}
/*
* create_degenerate_grouping_paths
*
* When the grouping is degenerate (see is_degenerate_grouping), we are
* supposed to emit either zero or one row for each grouping set depending on
* whether HAVING succeeds. Furthermore, there cannot be any variables in
* either HAVING or the targetlist, so we actually do not need the FROM table
* at all! We can just throw away the plan-so-far and generate a Result node.
* This is a sufficiently unusual corner case that it's not worth contorting
* the structure of this module to avoid having to generate the earlier paths
* in the first place.
*/
static void
create_degenerate_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
RelOptInfo *grouped_rel)
{
Query *parse = root->parse;
int nrows;
Path *path;
nrows = list_length(parse->groupingSets);
if (nrows > 1)
{
/*
* Doesn't seem worthwhile writing code to cons up a generate_series
* or a values scan to emit multiple rows. Instead just make N clones
* and append them. (With a volatile HAVING clause, this means you
* might get between 0 and N output rows. Offhand I think that's
* desired.)
*/
List *paths = NIL;
while (--nrows >= 0)
{
path = (Path *)
create_group_result_path(root, grouped_rel,
grouped_rel->reltarget,
(List *) parse->havingQual);
paths = lappend(paths, path);
}
path = (Path *)
create_append_path(root,
grouped_rel,
paths,
NIL,
NIL,
NULL,
0,
false,
-1);
}
else
{
/* No grouping sets, or just one, so one output row */
path = (Path *)
create_group_result_path(root, grouped_rel,
grouped_rel->reltarget,
(List *) parse->havingQual);
}
add_path(grouped_rel, path);
}
/*
* create_ordinary_grouping_paths
*
* Create grouping paths for the ordinary (that is, non-degenerate) case.
*
* We need to consider sorted and hashed aggregation in the same function,
* because otherwise (1) it would be harder to throw an appropriate error
* message if neither way works, and (2) we should not allow hashtable size
* considerations to dissuade us from using hashing if sorting is not possible.
*
* *partially_grouped_rel_p will be set to the partially grouped rel which this
* function creates, or to NULL if it doesn't create one.
*/
static void
create_ordinary_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
RelOptInfo *grouped_rel,
const AggClauseCosts *agg_costs,
grouping_sets_data *gd,
GroupPathExtraData *extra,
RelOptInfo **partially_grouped_rel_p)
{
Path *cheapest_path = input_rel->cheapest_total_path;
RelOptInfo *partially_grouped_rel = NULL;
double dNumGroups;
PartitionwiseAggregateType patype = PARTITIONWISE_AGGREGATE_NONE;
/*
* If this is the topmost grouping relation or if the parent relation is
* doing some form of partitionwise aggregation, then we may be able to do
* it at this level also. However, if the input relation is not
* partitioned, partitionwise aggregate is impossible.
*/
if (extra->patype != PARTITIONWISE_AGGREGATE_NONE &&
IS_PARTITIONED_REL(input_rel))
{
/*
* If this is the topmost relation or if the parent relation is doing
* full partitionwise aggregation, then we can do full partitionwise
* aggregation provided that the GROUP BY clause contains all of the
* partitioning columns at this level. Otherwise, we can do at most
* partial partitionwise aggregation. But if partial aggregation is
* not supported in general then we can't use it for partitionwise
* aggregation either.
*/
if (extra->patype == PARTITIONWISE_AGGREGATE_FULL &&
group_by_has_partkey(input_rel, extra->targetList,
root->parse->groupClause))
patype = PARTITIONWISE_AGGREGATE_FULL;
else if ((extra->flags & GROUPING_CAN_PARTIAL_AGG) != 0)
patype = PARTITIONWISE_AGGREGATE_PARTIAL;
else
patype = PARTITIONWISE_AGGREGATE_NONE;
}
/*
* Before generating paths for grouped_rel, we first generate any possible
* partially grouped paths; that way, later code can easily consider both
* parallel and non-parallel approaches to grouping.
*/
if ((extra->flags & GROUPING_CAN_PARTIAL_AGG) != 0)
{
bool force_rel_creation;
/*
* If we're doing partitionwise aggregation at this level, force
* creation of a partially_grouped_rel so we can add partitionwise
* paths to it.
*/
force_rel_creation = (patype == PARTITIONWISE_AGGREGATE_PARTIAL);
partially_grouped_rel =
create_partial_grouping_paths(root,
grouped_rel,
input_rel,
gd,
extra,
force_rel_creation);
}
/* Set out parameter. */
*partially_grouped_rel_p = partially_grouped_rel;
/* Apply partitionwise aggregation technique, if possible. */
if (patype != PARTITIONWISE_AGGREGATE_NONE)
create_partitionwise_grouping_paths(root, input_rel, grouped_rel,
partially_grouped_rel, agg_costs,
gd, patype, extra);
/* If we are doing partial aggregation only, return. */
if (extra->patype == PARTITIONWISE_AGGREGATE_PARTIAL)
{
Assert(partially_grouped_rel);
if (partially_grouped_rel->pathlist)
set_cheapest(partially_grouped_rel);
return;
}
/* Gather any partially grouped partial paths. */
if (partially_grouped_rel && partially_grouped_rel->partial_pathlist)
{
gather_grouping_paths(root, partially_grouped_rel);
set_cheapest(partially_grouped_rel);
}
/*
* Estimate number of groups.
*/
dNumGroups = get_number_of_groups(root,
cheapest_path->rows,
gd,
extra->targetList);
/* Build final grouping paths */
add_paths_to_grouping_rel(root, input_rel, grouped_rel,
partially_grouped_rel, agg_costs, gd,
dNumGroups, extra);
/* Give a helpful error if we failed to find any implementation */
if (grouped_rel->pathlist == NIL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("could not implement GROUP BY"),
errdetail("Some of the datatypes only support hashing, while others only support sorting.")));
/*
* If there is an FDW that's responsible for all baserels of the query,
* let it consider adding ForeignPaths.
*/
if (grouped_rel->fdwroutine &&
grouped_rel->fdwroutine->GetForeignUpperPaths)
grouped_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_GROUP_AGG,
input_rel, grouped_rel,
extra);
/* Let extensions possibly add some more paths */
if (create_upper_paths_hook)
(*create_upper_paths_hook) (root, UPPERREL_GROUP_AGG,
input_rel, grouped_rel,
extra);
}
/*
* For a given input path, consider the possible ways of doing grouping sets on
* it, by combinations of hashing and sorting. This can be called multiple
* times, so it's important that it not scribble on input. No result is
* returned, but any generated paths are added to grouped_rel.
*/
static void
consider_groupingsets_paths(PlannerInfo *root,
RelOptInfo *grouped_rel,
Path *path,
bool is_sorted,
bool can_hash,
grouping_sets_data *gd,
const AggClauseCosts *agg_costs,
double dNumGroups)
{
Query *parse = root->parse;
Size hash_mem_limit = get_hash_memory_limit();
/*
* If we're not being offered sorted input, then only consider plans that
* can be done entirely by hashing.
*
* We can hash everything if it looks like it'll fit in hash_mem. But if
* the input is actually sorted despite not being advertised as such, we
* prefer to make use of that in order to use less memory.
*
* If none of the grouping sets are sortable, then ignore the hash_mem
* limit and generate a path anyway, since otherwise we'll just fail.
*/
if (!is_sorted)
{
List *new_rollups = NIL;
RollupData *unhashed_rollup = NULL;
List *sets_data;
List *empty_sets_data = NIL;
List *empty_sets = NIL;
ListCell *lc;
ListCell *l_start = list_head(gd->rollups);
AggStrategy strat = AGG_HASHED;
double hashsize;
double exclude_groups = 0.0;
Assert(can_hash);
/*
* If the input is coincidentally sorted usefully (which can happen
* even if is_sorted is false, since that only means that our caller
* has set up the sorting for us), then save some hashtable space by
* making use of that. But we need to watch out for degenerate cases:
*
* 1) If there are any empty grouping sets, then group_pathkeys might
* be NIL if all non-empty grouping sets are unsortable. In this case,
* there will be a rollup containing only empty groups, and the
* pathkeys_contained_in test is vacuously true; this is ok.
*
* XXX: the above relies on the fact that group_pathkeys is generated
* from the first rollup. If we add the ability to consider multiple
* sort orders for grouping input, this assumption might fail.
*
* 2) If there are no empty sets and only unsortable sets, then the
* rollups list will be empty (and thus l_start == NULL), and
* group_pathkeys will be NIL; we must ensure that the vacuously-true
* pathkeys_contained_in test doesn't cause us to crash.
*/
if (l_start != NULL &&
pathkeys_contained_in(root->group_pathkeys, path->pathkeys))
{
unhashed_rollup = lfirst_node(RollupData, l_start);
exclude_groups = unhashed_rollup->numGroups;
l_start = lnext(gd->rollups, l_start);
}
hashsize = estimate_hashagg_tablesize(root,
path,
agg_costs,
dNumGroups - exclude_groups);
/*
* gd->rollups is empty if we have only unsortable columns to work
* with. Override hash_mem in that case; otherwise, we'll rely on the
* sorted-input case to generate usable mixed paths.
*/
if (hashsize > hash_mem_limit && gd->rollups)
return; /* nope, won't fit */
/*
* We need to burst the existing rollups list into individual grouping
* sets and recompute a groupClause for each set.
*/
sets_data = list_copy(gd->unsortable_sets);
for_each_cell(lc, gd->rollups, l_start)
{
RollupData *rollup = lfirst_node(RollupData, lc);
/*
* If we find an unhashable rollup that's not been skipped by the
* "actually sorted" check above, we can't cope; we'd need sorted
* input (with a different sort order) but we can't get that here.
* So bail out; we'll get a valid path from the is_sorted case
* instead.
*
* The mere presence of empty grouping sets doesn't make a rollup
* unhashable (see preprocess_grouping_sets), we handle those
* specially below.
*/
if (!rollup->hashable)
return;
sets_data = list_concat(sets_data, rollup->gsets_data);
}
foreach(lc, sets_data)
{
GroupingSetData *gs = lfirst_node(GroupingSetData, lc);
List *gset = gs->set;
RollupData *rollup;
if (gset == NIL)
{
/* Empty grouping sets can't be hashed. */
empty_sets_data = lappend(empty_sets_data, gs);
empty_sets = lappend(empty_sets, NIL);
}
else
{
rollup = makeNode(RollupData);
rollup->groupClause = preprocess_groupclause(root, gset);
rollup->gsets_data = list_make1(gs);
rollup->gsets = remap_to_groupclause_idx(rollup->groupClause,
rollup->gsets_data,
gd->tleref_to_colnum_map);
rollup->numGroups = gs->numGroups;
rollup->hashable = true;
rollup->is_hashed = true;
new_rollups = lappend(new_rollups, rollup);
}
}
/*
* If we didn't find anything nonempty to hash, then bail. We'll
* generate a path from the is_sorted case.
*/
if (new_rollups == NIL)
return;
/*
* If there were empty grouping sets they should have been in the
* first rollup.
*/
Assert(!unhashed_rollup || !empty_sets);
if (unhashed_rollup)
{
new_rollups = lappend(new_rollups, unhashed_rollup);
strat = AGG_MIXED;
}
else if (empty_sets)
{
RollupData *rollup = makeNode(RollupData);
rollup->groupClause = NIL;
rollup->gsets_data = empty_sets_data;
rollup->gsets = empty_sets;
rollup->numGroups = list_length(empty_sets);
rollup->hashable = false;
rollup->is_hashed = false;
new_rollups = lappend(new_rollups, rollup);
strat = AGG_MIXED;
}
add_path(grouped_rel, (Path *)
create_groupingsets_path(root,
grouped_rel,
path,
(List *) parse->havingQual,
strat,
new_rollups,
agg_costs,
dNumGroups));
return;
}
/*
* If we have sorted input but nothing we can do with it, bail.
*/
if (list_length(gd->rollups) == 0)
return;
/*
* Given sorted input, we try and make two paths: one sorted and one mixed
* sort/hash. (We need to try both because hashagg might be disabled, or
* some columns might not be sortable.)
*
* can_hash is passed in as false if some obstacle elsewhere (such as
* ordered aggs) means that we shouldn't consider hashing at all.
*/
if (can_hash && gd->any_hashable)
{
List *rollups = NIL;
List *hash_sets = list_copy(gd->unsortable_sets);
double availspace = hash_mem_limit;
ListCell *lc;
/*
* Account first for space needed for groups we can't sort at all.
*/
availspace -= estimate_hashagg_tablesize(root,
path,
agg_costs,
gd->dNumHashGroups);
if (availspace > 0 && list_length(gd->rollups) > 1)
{
double scale;
int num_rollups = list_length(gd->rollups);
int k_capacity;
int *k_weights = palloc(num_rollups * sizeof(int));
Bitmapset *hash_items = NULL;
int i;
/*
* We treat this as a knapsack problem: the knapsack capacity
* represents hash_mem, the item weights are the estimated memory
* usage of the hashtables needed to implement a single rollup,
* and we really ought to use the cost saving as the item value;
* however, currently the costs assigned to sort nodes don't
* reflect the comparison costs well, and so we treat all items as
* of equal value (each rollup we hash instead saves us one sort).
*
* To use the discrete knapsack, we need to scale the values to a
* reasonably small bounded range. We choose to allow a 5% error
* margin; we have no more than 4096 rollups in the worst possible
* case, which with a 5% error margin will require a bit over 42MB
* of workspace. (Anyone wanting to plan queries that complex had
* better have the memory for it. In more reasonable cases, with
* no more than a couple of dozen rollups, the memory usage will
* be negligible.)
*
* k_capacity is naturally bounded, but we clamp the values for
* scale and weight (below) to avoid overflows or underflows (or
* uselessly trying to use a scale factor less than 1 byte).
*/
scale = Max(availspace / (20.0 * num_rollups), 1.0);
k_capacity = (int) floor(availspace / scale);
/*
* We leave the first rollup out of consideration since it's the
* one that matches the input sort order. We assign indexes "i"
* to only those entries considered for hashing; the second loop,
* below, must use the same condition.
*/
i = 0;
for_each_from(lc, gd->rollups, 1)
{
RollupData *rollup = lfirst_node(RollupData, lc);
if (rollup->hashable)
{
double sz = estimate_hashagg_tablesize(root,
path,
agg_costs,
rollup->numGroups);
/*
* If sz is enormous, but hash_mem (and hence scale) is
* small, avoid integer overflow here.
*/
k_weights[i] = (int) Min(floor(sz / scale),
k_capacity + 1.0);
++i;
}
}
/*
* Apply knapsack algorithm; compute the set of items which
* maximizes the value stored (in this case the number of sorts
* saved) while keeping the total size (approximately) within
* capacity.
*/
if (i > 0)
hash_items = DiscreteKnapsack(k_capacity, i, k_weights, NULL);
if (!bms_is_empty(hash_items))
{
rollups = list_make1(linitial(gd->rollups));
i = 0;
for_each_from(lc, gd->rollups, 1)
{
RollupData *rollup = lfirst_node(RollupData, lc);
if (rollup->hashable)
{
if (bms_is_member(i, hash_items))
hash_sets = list_concat(hash_sets,
rollup->gsets_data);
else
rollups = lappend(rollups, rollup);
++i;
}
else
rollups = lappend(rollups, rollup);
}
}
}
if (!rollups && hash_sets)
rollups = list_copy(gd->rollups);
foreach(lc, hash_sets)
{
GroupingSetData *gs = lfirst_node(GroupingSetData, lc);
RollupData *rollup = makeNode(RollupData);
Assert(gs->set != NIL);
rollup->groupClause = preprocess_groupclause(root, gs->set);
rollup->gsets_data = list_make1(gs);
rollup->gsets = remap_to_groupclause_idx(rollup->groupClause,
rollup->gsets_data,
gd->tleref_to_colnum_map);
rollup->numGroups = gs->numGroups;
rollup->hashable = true;
rollup->is_hashed = true;
rollups = lcons(rollup, rollups);
}
if (rollups)
{
add_path(grouped_rel, (Path *)
create_groupingsets_path(root,
grouped_rel,
path,
(List *) parse->havingQual,
AGG_MIXED,
rollups,
agg_costs,
dNumGroups));
}
}
/*
* Now try the simple sorted case.
*/
if (!gd->unsortable_sets)
add_path(grouped_rel, (Path *)
create_groupingsets_path(root,
grouped_rel,
path,
(List *) parse->havingQual,
AGG_SORTED,
gd->rollups,
agg_costs,
dNumGroups));
}
/*
* create_window_paths
*
* Build a new upperrel containing Paths for window-function evaluation.
*
* input_rel: contains the source-data Paths
* input_target: result of make_window_input_target
* output_target: what the topmost WindowAggPath should return
* wflists: result of find_window_functions
* activeWindows: result of select_active_windows
*
* Note: all Paths in input_rel are expected to return input_target.
*/
static RelOptInfo *
create_window_paths(PlannerInfo *root,
RelOptInfo *input_rel,
PathTarget *input_target,
PathTarget *output_target,
bool output_target_parallel_safe,
WindowFuncLists *wflists,
List *activeWindows)
{
RelOptInfo *window_rel;
ListCell *lc;
/* For now, do all work in the (WINDOW, NULL) upperrel */
window_rel = fetch_upper_rel(root, UPPERREL_WINDOW, NULL);
/*
* If the input relation is not parallel-safe, then the window relation
* can't be parallel-safe, either. Otherwise, we need to examine the
* target list and active windows for non-parallel-safe constructs.
*/
if (input_rel->consider_parallel && output_target_parallel_safe &&
is_parallel_safe(root, (Node *) activeWindows))
window_rel->consider_parallel = true;
/*
* If the input rel belongs to a single FDW, so does the window rel.
*/
window_rel->serverid = input_rel->serverid;
window_rel->userid = input_rel->userid;
window_rel->useridiscurrent = input_rel->useridiscurrent;
window_rel->fdwroutine = input_rel->fdwroutine;
/*
* Consider computing window functions starting from the existing
* cheapest-total path (which will likely require a sort) as well as any
* existing paths that satisfy or partially satisfy root->window_pathkeys.
*/
foreach(lc, input_rel->pathlist)
{
Path *path = (Path *) lfirst(lc);
int presorted_keys;
if (path == input_rel->cheapest_total_path ||
pathkeys_count_contained_in(root->window_pathkeys, path->pathkeys,
&presorted_keys) ||
presorted_keys > 0)
create_one_window_path(root,
window_rel,
path,
input_target,
output_target,
wflists,
activeWindows);
}
/*
* If there is an FDW that's responsible for all baserels of the query,
* let it consider adding ForeignPaths.
*/
if (window_rel->fdwroutine &&
window_rel->fdwroutine->GetForeignUpperPaths)
window_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_WINDOW,
input_rel, window_rel,
NULL);
/* Let extensions possibly add some more paths */
if (create_upper_paths_hook)
(*create_upper_paths_hook) (root, UPPERREL_WINDOW,
input_rel, window_rel, NULL);
/* Now choose the best path(s) */
set_cheapest(window_rel);
return window_rel;
}
/*
* Stack window-function implementation steps atop the given Path, and
* add the result to window_rel.
*
* window_rel: upperrel to contain result
* path: input Path to use (must return input_target)
* input_target: result of make_window_input_target
* output_target: what the topmost WindowAggPath should return
* wflists: result of find_window_functions
* activeWindows: result of select_active_windows
*/
static void
create_one_window_path(PlannerInfo *root,
RelOptInfo *window_rel,
Path *path,
PathTarget *input_target,
PathTarget *output_target,
WindowFuncLists *wflists,
List *activeWindows)
{
PathTarget *window_target;
ListCell *l;
/*
* Since each window clause could require a different sort order, we stack
* up a WindowAgg node for each clause, with sort steps between them as
* needed. (We assume that select_active_windows chose a good order for
* executing the clauses in.)
*
* input_target should contain all Vars and Aggs needed for the result.
* (In some cases we wouldn't need to propagate all of these all the way
* to the top, since they might only be needed as inputs to WindowFuncs.
* It's probably not worth trying to optimize that though.) It must also
* contain all window partitioning and sorting expressions, to ensure
* they're computed only once at the bottom of the stack (that's critical
* for volatile functions). As we climb up the stack, we'll add outputs
* for the WindowFuncs computed at each level.
*/
window_target = input_target;
foreach(l, activeWindows)
{
WindowClause *wc = lfirst_node(WindowClause, l);
List *window_pathkeys;
int presorted_keys;
bool is_sorted;
window_pathkeys = make_pathkeys_for_window(root,
wc,
root->processed_tlist);
is_sorted = pathkeys_count_contained_in(window_pathkeys,
path->pathkeys,
&presorted_keys);
/* Sort if necessary */
if (!is_sorted)
{
/*
* No presorted keys or incremental sort disabled, just perform a
* complete sort.
*/
if (presorted_keys == 0 || !enable_incremental_sort)
path = (Path *) create_sort_path(root, window_rel,
path,
window_pathkeys,
-1.0);
else
{
/*
* Since we have presorted keys and incremental sort is
* enabled, just use incremental sort.
*/
path = (Path *) create_incremental_sort_path(root,
window_rel,
path,
window_pathkeys,
presorted_keys,
-1.0);
}
}
if (lnext(activeWindows, l))
{
/*
* Add the current WindowFuncs to the output target for this
* intermediate WindowAggPath. We must copy window_target to
* avoid changing the previous path's target.
*
* Note: a WindowFunc adds nothing to the target's eval costs; but
* we do need to account for the increase in tlist width.
*/
ListCell *lc2;
window_target = copy_pathtarget(window_target);
foreach(lc2, wflists->windowFuncs[wc->winref])
{
WindowFunc *wfunc = lfirst_node(WindowFunc, lc2);
add_column_to_pathtarget(window_target, (Expr *) wfunc, 0);
window_target->width += get_typavgwidth(wfunc->wintype, -1);
}
}
else
{
/* Install the goal target in the topmost WindowAgg */
window_target = output_target;
}
path = (Path *)
create_windowagg_path(root, window_rel, path, window_target,
wflists->windowFuncs[wc->winref],
wc);
}
add_path(window_rel, path);
}
/*
* create_distinct_paths
*
* Build a new upperrel containing Paths for SELECT DISTINCT evaluation.
*
* input_rel: contains the source-data Paths
*
* Note: input paths should already compute the desired pathtarget, since
* Sort/Unique won't project anything.
*/
static RelOptInfo *
create_distinct_paths(PlannerInfo *root,
RelOptInfo *input_rel)
{
Query *parse = root->parse;
Path *cheapest_input_path = input_rel->cheapest_total_path;
RelOptInfo *distinct_rel;
double numDistinctRows;
bool allow_hash;
Path *path;
ListCell *lc;
/* For now, do all work in the (DISTINCT, NULL) upperrel */
distinct_rel = fetch_upper_rel(root, UPPERREL_DISTINCT, NULL);
/*
* We don't compute anything at this level, so distinct_rel will be
* parallel-safe if the input rel is parallel-safe. In particular, if
* there is a DISTINCT ON (...) clause, any path for the input_rel will
* output those expressions, and will not be parallel-safe unless those
* expressions are parallel-safe.
*/
distinct_rel->consider_parallel = input_rel->consider_parallel;
/*
* If the input rel belongs to a single FDW, so does the distinct_rel.
*/
distinct_rel->serverid = input_rel->serverid;
distinct_rel->userid = input_rel->userid;
distinct_rel->useridiscurrent = input_rel->useridiscurrent;
distinct_rel->fdwroutine = input_rel->fdwroutine;
/* Estimate number of distinct rows there will be */
if (parse->groupClause || parse->groupingSets || parse->hasAggs ||
root->hasHavingQual)
{
/*
* If there was grouping or aggregation, use the number of input rows
* as the estimated number of DISTINCT rows (ie, assume the input is
* already mostly unique).
*/
numDistinctRows = cheapest_input_path->rows;
}
else
{
/*
* Otherwise, the UNIQUE filter has effects comparable to GROUP BY.
*/
List *distinctExprs;
distinctExprs = get_sortgrouplist_exprs(parse->distinctClause,
parse->targetList);
numDistinctRows = estimate_num_groups(root, distinctExprs,
cheapest_input_path->rows,
NULL, NULL);
}
/*
* Consider sort-based implementations of DISTINCT, if possible.
*/
if (grouping_is_sortable(parse->distinctClause))
{
/*
* First, if we have any adequately-presorted paths, just stick a
* Unique node on those. Then consider doing an explicit sort of the
* cheapest input path and Unique'ing that.
*
* When we have DISTINCT ON, we must sort by the more rigorous of
* DISTINCT and ORDER BY, else it won't have the desired behavior.
* Also, if we do have to do an explicit sort, we might as well use
* the more rigorous ordering to avoid a second sort later. (Note
* that the parser will have ensured that one clause is a prefix of
* the other.)
*/
List *needed_pathkeys;
if (parse->hasDistinctOn &&
list_length(root->distinct_pathkeys) <
list_length(root->sort_pathkeys))
needed_pathkeys = root->sort_pathkeys;
else
needed_pathkeys = root->distinct_pathkeys;
foreach(lc, input_rel->pathlist)
{
Path *path = (Path *) lfirst(lc);
if (pathkeys_contained_in(needed_pathkeys, path->pathkeys))
{
add_path(distinct_rel, (Path *)
create_upper_unique_path(root, distinct_rel,
path,
list_length(root->distinct_pathkeys),
numDistinctRows));
}
}
/* For explicit-sort case, always use the more rigorous clause */
if (list_length(root->distinct_pathkeys) <
list_length(root->sort_pathkeys))
{
needed_pathkeys = root->sort_pathkeys;
/* Assert checks that parser didn't mess up... */
Assert(pathkeys_contained_in(root->distinct_pathkeys,
needed_pathkeys));
}
else
needed_pathkeys = root->distinct_pathkeys;
path = cheapest_input_path;
if (!pathkeys_contained_in(needed_pathkeys, path->pathkeys))
path = (Path *) create_sort_path(root, distinct_rel,
path,
needed_pathkeys,
-1.0);
add_path(distinct_rel, (Path *)
create_upper_unique_path(root, distinct_rel,
path,
list_length(root->distinct_pathkeys),
numDistinctRows));
}
/*
* Consider hash-based implementations of DISTINCT, if possible.
*
* If we were not able to make any other types of path, we *must* hash or
* die trying. If we do have other choices, there are two things that
* should prevent selection of hashing: if the query uses DISTINCT ON
* (because it won't really have the expected behavior if we hash), or if
* enable_hashagg is off.
*
* Note: grouping_is_hashable() is much more expensive to check than the
* other gating conditions, so we want to do it last.
*/
if (distinct_rel->pathlist == NIL)
allow_hash = true; /* we have no alternatives */
else if (parse->hasDistinctOn || !enable_hashagg)
allow_hash = false; /* policy-based decision not to hash */
else
allow_hash = true; /* default */
if (allow_hash && grouping_is_hashable(parse->distinctClause))
{
/* Generate hashed aggregate path --- no sort needed */
add_path(distinct_rel, (Path *)
create_agg_path(root,
distinct_rel,
cheapest_input_path,
cheapest_input_path->pathtarget,
AGG_HASHED,
AGGSPLIT_SIMPLE,
parse->distinctClause,
NIL,
NULL,
numDistinctRows));
}
/* Give a helpful error if we failed to find any implementation */
if (distinct_rel->pathlist == NIL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("could not implement DISTINCT"),
errdetail("Some of the datatypes only support hashing, while others only support sorting.")));
/*
* If there is an FDW that's responsible for all baserels of the query,
* let it consider adding ForeignPaths.
*/
if (distinct_rel->fdwroutine &&
distinct_rel->fdwroutine->GetForeignUpperPaths)
distinct_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_DISTINCT,
input_rel, distinct_rel,
NULL);
/* Let extensions possibly add some more paths */
if (create_upper_paths_hook)
(*create_upper_paths_hook) (root, UPPERREL_DISTINCT,
input_rel, distinct_rel, NULL);
/* Now choose the best path(s) */
set_cheapest(distinct_rel);
return distinct_rel;
}
/*
* create_ordered_paths
*
* Build a new upperrel containing Paths for ORDER BY evaluation.
*
* All paths in the result must satisfy the ORDER BY ordering.
* The only new paths we need consider are an explicit full sort
* and incremental sort on the cheapest-total existing path.
*
* input_rel: contains the source-data Paths
* target: the output tlist the result Paths must emit
* limit_tuples: estimated bound on the number of output tuples,
* or -1 if no LIMIT or couldn't estimate
*
* XXX This only looks at sort_pathkeys. I wonder if it needs to look at the
* other pathkeys (grouping, ...) like generate_useful_gather_paths.
*/
static RelOptInfo *
create_ordered_paths(PlannerInfo *root,
RelOptInfo *input_rel,
PathTarget *target,
bool target_parallel_safe,
double limit_tuples)
{
Path *cheapest_input_path = input_rel->cheapest_total_path;
RelOptInfo *ordered_rel;
ListCell *lc;
/* For now, do all work in the (ORDERED, NULL) upperrel */
ordered_rel = fetch_upper_rel(root, UPPERREL_ORDERED, NULL);
/*
* If the input relation is not parallel-safe, then the ordered relation
* can't be parallel-safe, either. Otherwise, it's parallel-safe if the
* target list is parallel-safe.
*/
if (input_rel->consider_parallel && target_parallel_safe)
ordered_rel->consider_parallel = true;
/*
* If the input rel belongs to a single FDW, so does the ordered_rel.
*/
ordered_rel->serverid = input_rel->serverid;
ordered_rel->userid = input_rel->userid;
ordered_rel->useridiscurrent = input_rel->useridiscurrent;
ordered_rel->fdwroutine = input_rel->fdwroutine;
foreach(lc, input_rel->pathlist)
{
Path *input_path = (Path *) lfirst(lc);
Path *sorted_path = input_path;
bool is_sorted;
int presorted_keys;
is_sorted = pathkeys_count_contained_in(root->sort_pathkeys,
input_path->pathkeys, &presorted_keys);
if (is_sorted)
{
/* Use the input path as is, but add a projection step if needed */
if (sorted_path->pathtarget != target)
sorted_path = apply_projection_to_path(root, ordered_rel,
sorted_path, target);
add_path(ordered_rel, sorted_path);
}
else
{
/*
* Try adding an explicit sort, but only to the cheapest total
* path since a full sort should generally add the same cost to
* all paths.
*/
if (input_path == cheapest_input_path)
{
/*
* Sort the cheapest input path. An explicit sort here can
* take advantage of LIMIT.
*/
sorted_path = (Path *) create_sort_path(root,
ordered_rel,
input_path,
root->sort_pathkeys,
limit_tuples);
/* Add projection step if needed */
if (sorted_path->pathtarget != target)
sorted_path = apply_projection_to_path(root, ordered_rel,
sorted_path, target);
add_path(ordered_rel, sorted_path);
}
/*
* If incremental sort is enabled, then try it as well. Unlike
* with regular sorts, we can't just look at the cheapest path,
* because the cost of incremental sort depends on how well
* presorted the path is. Additionally incremental sort may enable
* a cheaper startup path to win out despite higher total cost.
*/
if (!enable_incremental_sort)
continue;
/* Likewise, if the path can't be used for incremental sort. */
if (!presorted_keys)
continue;
/* Also consider incremental sort. */
sorted_path = (Path *) create_incremental_sort_path(root,
ordered_rel,
input_path,
root->sort_pathkeys,
presorted_keys,
limit_tuples);
/* Add projection step if needed */
if (sorted_path->pathtarget != target)
sorted_path = apply_projection_to_path(root, ordered_rel,
sorted_path, target);
add_path(ordered_rel, sorted_path);
}
}
/*
* generate_gather_paths() will have already generated a simple Gather
* path for the best parallel path, if any, and the loop above will have
* considered sorting it. Similarly, generate_gather_paths() will also
* have generated order-preserving Gather Merge plans which can be used
* without sorting if they happen to match the sort_pathkeys, and the loop
* above will have handled those as well. However, there's one more
* possibility: it may make sense to sort the cheapest partial path
* according to the required output order and then use Gather Merge.
*/
if (ordered_rel->consider_parallel && root->sort_pathkeys != NIL &&
input_rel->partial_pathlist != NIL)
{
Path *cheapest_partial_path;
cheapest_partial_path = linitial(input_rel->partial_pathlist);
/*
* If cheapest partial path doesn't need a sort, this is redundant
* with what's already been tried.
*/
if (!pathkeys_contained_in(root->sort_pathkeys,
cheapest_partial_path->pathkeys))
{
Path *path;
double total_groups;
path = (Path *) create_sort_path(root,
ordered_rel,
cheapest_partial_path,
root->sort_pathkeys,
limit_tuples);
total_groups = cheapest_partial_path->rows *
cheapest_partial_path->parallel_workers;
path = (Path *)
create_gather_merge_path(root, ordered_rel,
path,
path->pathtarget,
root->sort_pathkeys, NULL,
&total_groups);
/* Add projection step if needed */
if (path->pathtarget != target)
path = apply_projection_to_path(root, ordered_rel,
path, target);
add_path(ordered_rel, path);
}
/*
* Consider incremental sort with a gather merge on partial paths.
*
* We can also skip the entire loop when we only have a single-item
* sort_pathkeys because then we can't possibly have a presorted
* prefix of the list without having the list be fully sorted.
*/
if (enable_incremental_sort && list_length(root->sort_pathkeys) > 1)
{
ListCell *lc;
foreach(lc, input_rel->partial_pathlist)
{
Path *input_path = (Path *) lfirst(lc);
Path *sorted_path;
bool is_sorted;
int presorted_keys;
double total_groups;
/*
* We don't care if this is the cheapest partial path - we
* can't simply skip it, because it may be partially sorted in
* which case we want to consider adding incremental sort
* (instead of full sort, which is what happens above).
*/
is_sorted = pathkeys_count_contained_in(root->sort_pathkeys,
input_path->pathkeys,
&presorted_keys);
/* No point in adding incremental sort on fully sorted paths. */
if (is_sorted)
continue;
if (presorted_keys == 0)
continue;
/* Since we have presorted keys, consider incremental sort. */
sorted_path = (Path *) create_incremental_sort_path(root,
ordered_rel,
input_path,
root->sort_pathkeys,
presorted_keys,
limit_tuples);
total_groups = input_path->rows *
input_path->parallel_workers;
sorted_path = (Path *)
create_gather_merge_path(root, ordered_rel,
sorted_path,
sorted_path->pathtarget,
root->sort_pathkeys, NULL,
&total_groups);
/* Add projection step if needed */
if (sorted_path->pathtarget != target)
sorted_path = apply_projection_to_path(root, ordered_rel,
sorted_path, target);
add_path(ordered_rel, sorted_path);
}
}
}
/*
* If there is an FDW that's responsible for all baserels of the query,
* let it consider adding ForeignPaths.
*/
if (ordered_rel->fdwroutine &&
ordered_rel->fdwroutine->GetForeignUpperPaths)
ordered_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_ORDERED,
input_rel, ordered_rel,
NULL);
/* Let extensions possibly add some more paths */
if (create_upper_paths_hook)
(*create_upper_paths_hook) (root, UPPERREL_ORDERED,
input_rel, ordered_rel, NULL);
/*
* No need to bother with set_cheapest here; grouping_planner does not
* need us to do it.
*/
Assert(ordered_rel->pathlist != NIL);
return ordered_rel;
}
/*
* make_group_input_target
* Generate appropriate PathTarget for initial input to grouping nodes.
*
* If there is grouping or aggregation, the scan/join subplan cannot emit
* the query's final targetlist; for example, it certainly can't emit any
* aggregate function calls. This routine generates the correct target
* for the scan/join subplan.
*
* The query target list passed from the parser already contains entries
* for all ORDER BY and GROUP BY expressions, but it will not have entries
* for variables used only in HAVING clauses; so we need to add those
* variables to the subplan target list. Also, we flatten all expressions
* except GROUP BY items into their component variables; other expressions
* will be computed by the upper plan nodes rather than by the subplan.
* For example, given a query like
* SELECT a+b,SUM(c+d) FROM table GROUP BY a+b;
* we want to pass this targetlist to the subplan:
* a+b,c,d
* where the a+b target will be used by the Sort/Group steps, and the
* other targets will be used for computing the final results.
*
* 'final_target' is the query's final target list (in PathTarget form)
*
* The result is the PathTarget to be computed by the Paths returned from
* query_planner().
*/
static PathTarget *
make_group_input_target(PlannerInfo *root, PathTarget *final_target)
{
Query *parse = root->parse;
PathTarget *input_target;
List *non_group_cols;
List *non_group_vars;
int i;
ListCell *lc;
/*
* We must build a target containing all grouping columns, plus any other
* Vars mentioned in the query's targetlist and HAVING qual.
*/
input_target = create_empty_pathtarget();
non_group_cols = NIL;
i = 0;
foreach(lc, final_target->exprs)
{
Expr *expr = (Expr *) lfirst(lc);
Index sgref = get_pathtarget_sortgroupref(final_target, i);
if (sgref && parse->groupClause &&
get_sortgroupref_clause_noerr(sgref, parse->groupClause) != NULL)
{
/*
* It's a grouping column, so add it to the input target as-is.
*/
add_column_to_pathtarget(input_target, expr, sgref);
}
else
{
/*
* Non-grouping column, so just remember the expression for later
* call to pull_var_clause.
*/
non_group_cols = lappend(non_group_cols, expr);
}
i++;
}
/*
* If there's a HAVING clause, we'll need the Vars it uses, too.
*/
if (parse->havingQual)
non_group_cols = lappend(non_group_cols, parse->havingQual);
/*
* Pull out all the Vars mentioned in non-group cols (plus HAVING), and
* add them to the input target if not already present. (A Var used
* directly as a GROUP BY item will be present already.) Note this
* includes Vars used in resjunk items, so we are covering the needs of
* ORDER BY and window specifications. Vars used within Aggrefs and
* WindowFuncs will be pulled out here, too.
*/
non_group_vars = pull_var_clause((Node *) non_group_cols,
PVC_RECURSE_AGGREGATES |
PVC_RECURSE_WINDOWFUNCS |
PVC_INCLUDE_PLACEHOLDERS);
add_new_columns_to_pathtarget(input_target, non_group_vars);
/* clean up cruft */
list_free(non_group_vars);
list_free(non_group_cols);
/* XXX this causes some redundant cost calculation ... */
return set_pathtarget_cost_width(root, input_target);
}
/*
* make_partial_grouping_target
* Generate appropriate PathTarget for output of partial aggregate
* (or partial grouping, if there are no aggregates) nodes.
*
* A partial aggregation node needs to emit all the same aggregates that
* a regular aggregation node would, plus any aggregates used in HAVING;
* except that the Aggref nodes should be marked as partial aggregates.
*
* In addition, we'd better emit any Vars and PlaceHolderVars that are
* used outside of Aggrefs in the aggregation tlist and HAVING. (Presumably,
* these would be Vars that are grouped by or used in grouping expressions.)
*
* grouping_target is the tlist to be emitted by the topmost aggregation step.
* havingQual represents the HAVING clause.
*/
static PathTarget *
make_partial_grouping_target(PlannerInfo *root,
PathTarget *grouping_target,
Node *havingQual)
{
Query *parse = root->parse;
PathTarget *partial_target;
List *non_group_cols;
List *non_group_exprs;
int i;
ListCell *lc;
partial_target = create_empty_pathtarget();
non_group_cols = NIL;
i = 0;
foreach(lc, grouping_target->exprs)
{
Expr *expr = (Expr *) lfirst(lc);
Index sgref = get_pathtarget_sortgroupref(grouping_target, i);
if (sgref && parse->groupClause &&
get_sortgroupref_clause_noerr(sgref, parse->groupClause) != NULL)
{
/*
* It's a grouping column, so add it to the partial_target as-is.
* (This allows the upper agg step to repeat the grouping calcs.)
*/
add_column_to_pathtarget(partial_target, expr, sgref);
}
else
{
/*
* Non-grouping column, so just remember the expression for later
* call to pull_var_clause.
*/
non_group_cols = lappend(non_group_cols, expr);
}
i++;
}
/*
* If there's a HAVING clause, we'll need the Vars/Aggrefs it uses, too.
*/
if (havingQual)
non_group_cols = lappend(non_group_cols, havingQual);
/*
* Pull out all the Vars, PlaceHolderVars, and Aggrefs mentioned in
* non-group cols (plus HAVING), and add them to the partial_target if not
* already present. (An expression used directly as a GROUP BY item will
* be present already.) Note this includes Vars used in resjunk items, so
* we are covering the needs of ORDER BY and window specifications.
*/
non_group_exprs = pull_var_clause((Node *) non_group_cols,
PVC_INCLUDE_AGGREGATES |
PVC_RECURSE_WINDOWFUNCS |
PVC_INCLUDE_PLACEHOLDERS);
add_new_columns_to_pathtarget(partial_target, non_group_exprs);
/*
* Adjust Aggrefs to put them in partial mode. At this point all Aggrefs
* are at the top level of the target list, so we can just scan the list
* rather than recursing through the expression trees.
*/
foreach(lc, partial_target->exprs)
{
Aggref *aggref = (Aggref *) lfirst(lc);
if (IsA(aggref, Aggref))
{
Aggref *newaggref;
/*
* We shouldn't need to copy the substructure of the Aggref node,
* but flat-copy the node itself to avoid damaging other trees.
*/
newaggref = makeNode(Aggref);
memcpy(newaggref, aggref, sizeof(Aggref));
/* For now, assume serialization is required */
mark_partial_aggref(newaggref, AGGSPLIT_INITIAL_SERIAL);
lfirst(lc) = newaggref;
}
}
/* clean up cruft */
list_free(non_group_exprs);
list_free(non_group_cols);
/* XXX this causes some redundant cost calculation ... */
return set_pathtarget_cost_width(root, partial_target);
}
/*
* mark_partial_aggref
* Adjust an Aggref to make it represent a partial-aggregation step.
*
* The Aggref node is modified in-place; caller must do any copying required.
*/
void
mark_partial_aggref(Aggref *agg, AggSplit aggsplit)
{
/* aggtranstype should be computed by this point */
Assert(OidIsValid(agg->aggtranstype));
/* ... but aggsplit should still be as the parser left it */
Assert(agg->aggsplit == AGGSPLIT_SIMPLE);
/* Mark the Aggref with the intended partial-aggregation mode */
agg->aggsplit = aggsplit;
/*
* Adjust result type if needed. Normally, a partial aggregate returns
* the aggregate's transition type; but if that's INTERNAL and we're
* serializing, it returns BYTEA instead.
*/
if (DO_AGGSPLIT_SKIPFINAL(aggsplit))
{
if (agg->aggtranstype == INTERNALOID && DO_AGGSPLIT_SERIALIZE(aggsplit))
agg->aggtype = BYTEAOID;
else
agg->aggtype = agg->aggtranstype;
}
}
/*
* postprocess_setop_tlist
* Fix up targetlist returned by plan_set_operations().
*
* We need to transpose sort key info from the orig_tlist into new_tlist.
* NOTE: this would not be good enough if we supported resjunk sort keys
* for results of set operations --- then, we'd need to project a whole
* new tlist to evaluate the resjunk columns. For now, just ereport if we
* find any resjunk columns in orig_tlist.
*/
static List *
postprocess_setop_tlist(List *new_tlist, List *orig_tlist)
{
ListCell *l;
ListCell *orig_tlist_item = list_head(orig_tlist);
foreach(l, new_tlist)
{
TargetEntry *new_tle = lfirst_node(TargetEntry, l);
TargetEntry *orig_tle;
/* ignore resjunk columns in setop result */
if (new_tle->resjunk)
continue;
Assert(orig_tlist_item != NULL);
orig_tle = lfirst_node(TargetEntry, orig_tlist_item);
orig_tlist_item = lnext(orig_tlist, orig_tlist_item);
if (orig_tle->resjunk) /* should not happen */
elog(ERROR, "resjunk output columns are not implemented");
Assert(new_tle->resno == orig_tle->resno);
new_tle->ressortgroupref = orig_tle->ressortgroupref;
}
if (orig_tlist_item != NULL)
elog(ERROR, "resjunk output columns are not implemented");
return new_tlist;
}
/*
* select_active_windows
* Create a list of the "active" window clauses (ie, those referenced
* by non-deleted WindowFuncs) in the order they are to be executed.
*/
static List *
select_active_windows(PlannerInfo *root, WindowFuncLists *wflists)
{
List *windowClause = root->parse->windowClause;
List *result = NIL;
ListCell *lc;
int nActive = 0;
WindowClauseSortData *actives = palloc(sizeof(WindowClauseSortData)
* list_length(windowClause));
/* First, construct an array of the active windows */
foreach(lc, windowClause)
{
WindowClause *wc = lfirst_node(WindowClause, lc);
/* It's only active if wflists shows some related WindowFuncs */
Assert(wc->winref <= wflists->maxWinRef);
if (wflists->windowFuncs[wc->winref] == NIL)
continue;
actives[nActive].wc = wc; /* original clause */
/*
* For sorting, we want the list of partition keys followed by the
* list of sort keys. But pathkeys construction will remove duplicates
* between the two, so we can as well (even though we can't detect all
* of the duplicates, since some may come from ECs - that might mean
* we miss optimization chances here). We must, however, ensure that
* the order of entries is preserved with respect to the ones we do
* keep.
*
* partitionClause and orderClause had their own duplicates removed in
* parse analysis, so we're only concerned here with removing
* orderClause entries that also appear in partitionClause.
*/
actives[nActive].uniqueOrder =
list_concat_unique(list_copy(wc->partitionClause),
wc->orderClause);
nActive++;
}
/*
* Sort active windows by their partitioning/ordering clauses, ignoring
* any framing clauses, so that the windows that need the same sorting are
* adjacent in the list. When we come to generate paths, this will avoid
* inserting additional Sort nodes.
*
* This is how we implement a specific requirement from the SQL standard,
* which says that when two or more windows are order-equivalent (i.e.
* have matching partition and order clauses, even if their names or
* framing clauses differ), then all peer rows must be presented in the
* same order in all of them. If we allowed multiple sort nodes for such
* cases, we'd risk having the peer rows end up in different orders in
* equivalent windows due to sort instability. (See General Rule 4 of
* <window clause> in SQL2008 - SQL2016.)
*
* Additionally, if the entire list of clauses of one window is a prefix
* of another, put first the window with stronger sorting requirements.
* This way we will first sort for stronger window, and won't have to sort
* again for the weaker one.
*/
qsort(actives, nActive, sizeof(WindowClauseSortData), common_prefix_cmp);
/* build ordered list of the original WindowClause nodes */
for (int i = 0; i < nActive; i++)
result = lappend(result, actives[i].wc);
pfree(actives);
return result;
}
/*
* common_prefix_cmp
* QSort comparison function for WindowClauseSortData
*
* Sort the windows by the required sorting clauses. First, compare the sort
* clauses themselves. Second, if one window's clauses are a prefix of another
* one's clauses, put the window with more sort clauses first.
*/
static int
common_prefix_cmp(const void *a, const void *b)
{
const WindowClauseSortData *wcsa = a;
const WindowClauseSortData *wcsb = b;
ListCell *item_a;
ListCell *item_b;
forboth(item_a, wcsa->uniqueOrder, item_b, wcsb->uniqueOrder)
{
SortGroupClause *sca = lfirst_node(SortGroupClause, item_a);
SortGroupClause *scb = lfirst_node(SortGroupClause, item_b);
if (sca->tleSortGroupRef > scb->tleSortGroupRef)
return -1;
else if (sca->tleSortGroupRef < scb->tleSortGroupRef)
return 1;
else if (sca->sortop > scb->sortop)
return -1;
else if (sca->sortop < scb->sortop)
return 1;
else if (sca->nulls_first && !scb->nulls_first)
return -1;
else if (!sca->nulls_first && scb->nulls_first)
return 1;
/* no need to compare eqop, since it is fully determined by sortop */
}
if (list_length(wcsa->uniqueOrder) > list_length(wcsb->uniqueOrder))
return -1;
else if (list_length(wcsa->uniqueOrder) < list_length(wcsb->uniqueOrder))
return 1;
return 0;
}
/*
* make_window_input_target
* Generate appropriate PathTarget for initial input to WindowAgg nodes.
*
* When the query has window functions, this function computes the desired
* target to be computed by the node just below the first WindowAgg.
* This tlist must contain all values needed to evaluate the window functions,
* compute the final target list, and perform any required final sort step.
* If multiple WindowAggs are needed, each intermediate one adds its window
* function results onto this base tlist; only the topmost WindowAgg computes
* the actual desired target list.
*
* This function is much like make_group_input_target, though not quite enough
* like it to share code. As in that function, we flatten most expressions
* into their component variables. But we do not want to flatten window
* PARTITION BY/ORDER BY clauses, since that might result in multiple
* evaluations of them, which would be bad (possibly even resulting in
* inconsistent answers, if they contain volatile functions).
* Also, we must not flatten GROUP BY clauses that were left unflattened by
* make_group_input_target, because we may no longer have access to the
* individual Vars in them.
*
* Another key difference from make_group_input_target is that we don't
* flatten Aggref expressions, since those are to be computed below the
* window functions and just referenced like Vars above that.
*
* 'final_target' is the query's final target list (in PathTarget form)
* 'activeWindows' is the list of active windows previously identified by
* select_active_windows.
*
* The result is the PathTarget to be computed by the plan node immediately
* below the first WindowAgg node.
*/
static PathTarget *
make_window_input_target(PlannerInfo *root,
PathTarget *final_target,
List *activeWindows)
{
Query *parse = root->parse;
PathTarget *input_target;
Bitmapset *sgrefs;
List *flattenable_cols;
List *flattenable_vars;
int i;
ListCell *lc;
Assert(parse->hasWindowFuncs);
/*
* Collect the sortgroupref numbers of window PARTITION/ORDER BY clauses
* into a bitmapset for convenient reference below.
*/
sgrefs = NULL;
foreach(lc, activeWindows)
{
WindowClause *wc = lfirst_node(WindowClause, lc);
ListCell *lc2;
foreach(lc2, wc->partitionClause)
{
SortGroupClause *sortcl = lfirst_node(SortGroupClause, lc2);
sgrefs = bms_add_member(sgrefs, sortcl->tleSortGroupRef);
}
foreach(lc2, wc->orderClause)
{
SortGroupClause *sortcl = lfirst_node(SortGroupClause, lc2);
sgrefs = bms_add_member(sgrefs, sortcl->tleSortGroupRef);
}
}
/* Add in sortgroupref numbers of GROUP BY clauses, too */
foreach(lc, parse->groupClause)
{
SortGroupClause *grpcl = lfirst_node(SortGroupClause, lc);
sgrefs = bms_add_member(sgrefs, grpcl->tleSortGroupRef);
}
/*
* Construct a target containing all the non-flattenable targetlist items,
* and save aside the others for a moment.
*/
input_target = create_empty_pathtarget();
flattenable_cols = NIL;
i = 0;
foreach(lc, final_target->exprs)
{
Expr *expr = (Expr *) lfirst(lc);
Index sgref = get_pathtarget_sortgroupref(final_target, i);
/*
* Don't want to deconstruct window clauses or GROUP BY items. (Note
* that such items can't contain window functions, so it's okay to
* compute them below the WindowAgg nodes.)
*/
if (sgref != 0 && bms_is_member(sgref, sgrefs))
{
/*
* Don't want to deconstruct this value, so add it to the input
* target as-is.
*/
add_column_to_pathtarget(input_target, expr, sgref);
}
else
{
/*
* Column is to be flattened, so just remember the expression for
* later call to pull_var_clause.
*/
flattenable_cols = lappend(flattenable_cols, expr);
}
i++;
}
/*
* Pull out all the Vars and Aggrefs mentioned in flattenable columns, and
* add them to the input target if not already present. (Some might be
* there already because they're used directly as window/group clauses.)
*
* Note: it's essential to use PVC_INCLUDE_AGGREGATES here, so that any
* Aggrefs are placed in the Agg node's tlist and not left to be computed
* at higher levels. On the other hand, we should recurse into
* WindowFuncs to make sure their input expressions are available.
*/
flattenable_vars = pull_var_clause((Node *) flattenable_cols,
PVC_INCLUDE_AGGREGATES |
PVC_RECURSE_WINDOWFUNCS |
PVC_INCLUDE_PLACEHOLDERS);
add_new_columns_to_pathtarget(input_target, flattenable_vars);
/* clean up cruft */
list_free(flattenable_vars);
list_free(flattenable_cols);
/* XXX this causes some redundant cost calculation ... */
return set_pathtarget_cost_width(root, input_target);
}
/*
* make_pathkeys_for_window
* Create a pathkeys list describing the required input ordering
* for the given WindowClause.
*
* The required ordering is first the PARTITION keys, then the ORDER keys.
* In the future we might try to implement windowing using hashing, in which
* case the ordering could be relaxed, but for now we always sort.
*/
static List *
make_pathkeys_for_window(PlannerInfo *root, WindowClause *wc,
List *tlist)
{
List *window_pathkeys;
List *window_sortclauses;
/* Throw error if can't sort */
if (!grouping_is_sortable(wc->partitionClause))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("could not implement window PARTITION BY"),
errdetail("Window partitioning columns must be of sortable datatypes.")));
if (!grouping_is_sortable(wc->orderClause))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("could not implement window ORDER BY"),
errdetail("Window ordering columns must be of sortable datatypes.")));
/* Okay, make the combined pathkeys */
window_sortclauses = list_concat_copy(wc->partitionClause, wc->orderClause);
window_pathkeys = make_pathkeys_for_sortclauses(root,
window_sortclauses,
tlist);
list_free(window_sortclauses);
return window_pathkeys;
}
/*
* make_sort_input_target
* Generate appropriate PathTarget for initial input to Sort step.
*
* If the query has ORDER BY, this function chooses the target to be computed
* by the node just below the Sort (and DISTINCT, if any, since Unique can't
* project) steps. This might or might not be identical to the query's final
* output target.
*
* The main argument for keeping the sort-input tlist the same as the final
* is that we avoid a separate projection node (which will be needed if
* they're different, because Sort can't project). However, there are also
* advantages to postponing tlist evaluation till after the Sort: it ensures
* a consistent order of evaluation for any volatile functions in the tlist,
* and if there's also a LIMIT, we can stop the query without ever computing
* tlist functions for later rows, which is beneficial for both volatile and
* expensive functions.
*
* Our current policy is to postpone volatile expressions till after the sort
* unconditionally (assuming that that's possible, ie they are in plain tlist
* columns and not ORDER BY/GROUP BY/DISTINCT columns). We also prefer to
* postpone set-returning expressions, because running them beforehand would
* bloat the sort dataset, and because it might cause unexpected output order
* if the sort isn't stable. However there's a constraint on that: all SRFs
* in the tlist should be evaluated at the same plan step, so that they can
* run in sync in nodeProjectSet. So if any SRFs are in sort columns, we
* mustn't postpone any SRFs. (Note that in principle that policy should
* probably get applied to the group/window input targetlists too, but we
* have not done that historically.) Lastly, expensive expressions are
* postponed if there is a LIMIT, or if root->tuple_fraction shows that
* partial evaluation of the query is possible (if neither is true, we expect
* to have to evaluate the expressions for every row anyway), or if there are
* any volatile or set-returning expressions (since once we've put in a
* projection at all, it won't cost any more to postpone more stuff).
*
* Another issue that could potentially be considered here is that
* evaluating tlist expressions could result in data that's either wider
* or narrower than the input Vars, thus changing the volume of data that
* has to go through the Sort. However, we usually have only a very bad
* idea of the output width of any expression more complex than a Var,
* so for now it seems too risky to try to optimize on that basis.
*
* Note that if we do produce a modified sort-input target, and then the
* query ends up not using an explicit Sort, no particular harm is done:
* we'll initially use the modified target for the preceding path nodes,
* but then change them to the final target with apply_projection_to_path.
* Moreover, in such a case the guarantees about evaluation order of
* volatile functions still hold, since the rows are sorted already.
*
* This function has some things in common with make_group_input_target and
* make_window_input_target, though the detailed rules for what to do are
* different. We never flatten/postpone any grouping or ordering columns;
* those are needed before the sort. If we do flatten a particular
* expression, we leave Aggref and WindowFunc nodes alone, since those were
* computed earlier.
*
* 'final_target' is the query's final target list (in PathTarget form)
* 'have_postponed_srfs' is an output argument, see below
*
* The result is the PathTarget to be computed by the plan node immediately
* below the Sort step (and the Distinct step, if any). This will be
* exactly final_target if we decide a projection step wouldn't be helpful.
*
* In addition, *have_postponed_srfs is set to true if we choose to postpone
* any set-returning functions to after the Sort.
*/
static PathTarget *
make_sort_input_target(PlannerInfo *root,
PathTarget *final_target,
bool *have_postponed_srfs)
{
Query *parse = root->parse;
PathTarget *input_target;
int ncols;
bool *col_is_srf;
bool *postpone_col;
bool have_srf;
bool have_volatile;
bool have_expensive;
bool have_srf_sortcols;
bool postpone_srfs;
List *postponable_cols;
List *postponable_vars;
int i;
ListCell *lc;
/* Shouldn't get here unless query has ORDER BY */
Assert(parse->sortClause);
*have_postponed_srfs = false; /* default result */
/* Inspect tlist and collect per-column information */
ncols = list_length(final_target->exprs);
col_is_srf = (bool *) palloc0(ncols * sizeof(bool));
postpone_col = (bool *) palloc0(ncols * sizeof(bool));
have_srf = have_volatile = have_expensive = have_srf_sortcols = false;
i = 0;
foreach(lc, final_target->exprs)
{
Expr *expr = (Expr *) lfirst(lc);
/*
* If the column has a sortgroupref, assume it has to be evaluated
* before sorting. Generally such columns would be ORDER BY, GROUP
* BY, etc targets. One exception is columns that were removed from
* GROUP BY by remove_useless_groupby_columns() ... but those would
* only be Vars anyway. There don't seem to be any cases where it
* would be worth the trouble to double-check.
*/
if (get_pathtarget_sortgroupref(final_target, i) == 0)
{
/*
* Check for SRF or volatile functions. Check the SRF case first
* because we must know whether we have any postponed SRFs.
*/
if (parse->hasTargetSRFs &&
expression_returns_set((Node *) expr))
{
/* We'll decide below whether these are postponable */
col_is_srf[i] = true;
have_srf = true;
}
else if (contain_volatile_functions((Node *) expr))
{
/* Unconditionally postpone */
postpone_col[i] = true;
have_volatile = true;
}
else
{
/*
* Else check the cost. XXX it's annoying to have to do this
* when set_pathtarget_cost_width() just did it. Refactor to
* allow sharing the work?
*/
QualCost cost;
cost_qual_eval_node(&cost, (Node *) expr, root);
/*
* We arbitrarily define "expensive" as "more than 10X
* cpu_operator_cost". Note this will take in any PL function
* with default cost.
*/
if (cost.per_tuple > 10 * cpu_operator_cost)
{
postpone_col[i] = true;
have_expensive = true;
}
}
}
else
{
/* For sortgroupref cols, just check if any contain SRFs */
if (!have_srf_sortcols &&
parse->hasTargetSRFs &&
expression_returns_set((Node *) expr))
have_srf_sortcols = true;
}
i++;
}
/*
* We can postpone SRFs if we have some but none are in sortgroupref cols.
*/
postpone_srfs = (have_srf && !have_srf_sortcols);
/*
* If we don't need a post-sort projection, just return final_target.
*/
if (!(postpone_srfs || have_volatile ||
(have_expensive &&
(parse->limitCount || root->tuple_fraction > 0))))
return final_target;
/*
* Report whether the post-sort projection will contain set-returning
* functions. This is important because it affects whether the Sort can
* rely on the query's LIMIT (if any) to bound the number of rows it needs
* to return.
*/
*have_postponed_srfs = postpone_srfs;
/*
* Construct the sort-input target, taking all non-postponable columns and
* then adding Vars, PlaceHolderVars, Aggrefs, and WindowFuncs found in
* the postponable ones.
*/
input_target = create_empty_pathtarget();
postponable_cols = NIL;
i = 0;
foreach(lc, final_target->exprs)
{
Expr *expr = (Expr *) lfirst(lc);
if (postpone_col[i] || (postpone_srfs && col_is_srf[i]))
postponable_cols = lappend(postponable_cols, expr);
else
add_column_to_pathtarget(input_target, expr,
get_pathtarget_sortgroupref(final_target, i));
i++;
}
/*
* Pull out all the Vars, Aggrefs, and WindowFuncs mentioned in
* postponable columns, and add them to the sort-input target if not
* already present. (Some might be there already.) We mustn't
* deconstruct Aggrefs or WindowFuncs here, since the projection node
* would be unable to recompute them.
*/
postponable_vars = pull_var_clause((Node *) postponable_cols,
PVC_INCLUDE_AGGREGATES |
PVC_INCLUDE_WINDOWFUNCS |
PVC_INCLUDE_PLACEHOLDERS);
add_new_columns_to_pathtarget(input_target, postponable_vars);
/* clean up cruft */
list_free(postponable_vars);
list_free(postponable_cols);
/* XXX this represents even more redundant cost calculation ... */
return set_pathtarget_cost_width(root, input_target);
}
/*
* get_cheapest_fractional_path
* Find the cheapest path for retrieving a specified fraction of all
* the tuples expected to be returned by the given relation.
*
* We interpret tuple_fraction the same way as grouping_planner.
*
* We assume set_cheapest() has been run on the given rel.
*/
Path *
get_cheapest_fractional_path(RelOptInfo *rel, double tuple_fraction)
{
Path *best_path = rel->cheapest_total_path;
ListCell *l;
/* If all tuples will be retrieved, just return the cheapest-total path */
if (tuple_fraction <= 0.0)
return best_path;
/* Convert absolute # of tuples to a fraction; no need to clamp to 0..1 */
if (tuple_fraction >= 1.0 && best_path->rows > 0)
tuple_fraction /= best_path->rows;
foreach(l, rel->pathlist)
{
Path *path = (Path *) lfirst(l);
if (path == rel->cheapest_total_path ||
compare_fractional_path_costs(best_path, path, tuple_fraction) <= 0)
continue;
best_path = path;
}
return best_path;
}
/*
* adjust_paths_for_srfs
* Fix up the Paths of the given upperrel to handle tSRFs properly.
*
* The executor can only handle set-returning functions that appear at the
* top level of the targetlist of a ProjectSet plan node. If we have any SRFs
* that are not at top level, we need to split up the evaluation into multiple
* plan levels in which each level satisfies this constraint. This function
* modifies each Path of an upperrel that (might) compute any SRFs in its
* output tlist to insert appropriate projection steps.
*
* The given targets and targets_contain_srfs lists are from
* split_pathtarget_at_srfs(). We assume the existing Paths emit the first
* target in targets.
*/
static void
adjust_paths_for_srfs(PlannerInfo *root, RelOptInfo *rel,
List *targets, List *targets_contain_srfs)
{
ListCell *lc;
Assert(list_length(targets) == list_length(targets_contain_srfs));
Assert(!linitial_int(targets_contain_srfs));
/* If no SRFs appear at this plan level, nothing to do */
if (list_length(targets) == 1)
return;
/*
* Stack SRF-evaluation nodes atop each path for the rel.
*
* In principle we should re-run set_cheapest() here to identify the
* cheapest path, but it seems unlikely that adding the same tlist eval
* costs to all the paths would change that, so we don't bother. Instead,
* just assume that the cheapest-startup and cheapest-total paths remain
* so. (There should be no parameterized paths anymore, so we needn't
* worry about updating cheapest_parameterized_paths.)
*/
foreach(lc, rel->pathlist)
{
Path *subpath = (Path *) lfirst(lc);
Path *newpath = subpath;
ListCell *lc1,
*lc2;
Assert(subpath->param_info == NULL);
forboth(lc1, targets, lc2, targets_contain_srfs)
{
PathTarget *thistarget = lfirst_node(PathTarget, lc1);
bool contains_srfs = (bool) lfirst_int(lc2);
/* If this level doesn't contain SRFs, do regular projection */
if (contains_srfs)
newpath = (Path *) create_set_projection_path(root,
rel,
newpath,
thistarget);
else
newpath = (Path *) apply_projection_to_path(root,
rel,
newpath,
thistarget);
}
lfirst(lc) = newpath;
if (subpath == rel->cheapest_startup_path)
rel->cheapest_startup_path = newpath;
if (subpath == rel->cheapest_total_path)
rel->cheapest_total_path = newpath;
}
/* Likewise for partial paths, if any */
foreach(lc, rel->partial_pathlist)
{
Path *subpath = (Path *) lfirst(lc);
Path *newpath = subpath;
ListCell *lc1,
*lc2;
Assert(subpath->param_info == NULL);
forboth(lc1, targets, lc2, targets_contain_srfs)
{
PathTarget *thistarget = lfirst_node(PathTarget, lc1);
bool contains_srfs = (bool) lfirst_int(lc2);
/* If this level doesn't contain SRFs, do regular projection */
if (contains_srfs)
newpath = (Path *) create_set_projection_path(root,
rel,
newpath,
thistarget);
else
{
/* avoid apply_projection_to_path, in case of multiple refs */
newpath = (Path *) create_projection_path(root,
rel,
newpath,
thistarget);
}
}
lfirst(lc) = newpath;
}
}
/*
* expression_planner
* Perform planner's transformations on a standalone expression.
*
* Various utility commands need to evaluate expressions that are not part
* of a plannable query. They can do so using the executor's regular
* expression-execution machinery, but first the expression has to be fed
* through here to transform it from parser output to something executable.
*
* Currently, we disallow sublinks in standalone expressions, so there's no
* real "planning" involved here. (That might not always be true though.)
* What we must do is run eval_const_expressions to ensure that any function
* calls are converted to positional notation and function default arguments
* get inserted. The fact that constant subexpressions get simplified is a
* side-effect that is useful when the expression will get evaluated more than
* once. Also, we must fix operator function IDs.
*
* This does not return any information about dependencies of the expression.
* Hence callers should use the results only for the duration of the current
* query. Callers that would like to cache the results for longer should use
* expression_planner_with_deps, probably via the plancache.
*
* Note: this must not make any damaging changes to the passed-in expression
* tree. (It would actually be okay to apply fix_opfuncids to it, but since
* we first do an expression_tree_mutator-based walk, what is returned will
* be a new node tree.) The result is constructed in the current memory
* context; beware that this can leak a lot of additional stuff there, too.
*/
Expr *
expression_planner(Expr *expr)
{
Node *result;
/*
* Convert named-argument function calls, insert default arguments and
* simplify constant subexprs
*/
result = eval_const_expressions(NULL, (Node *) expr);
/* Fill in opfuncid values if missing */
fix_opfuncids(result);
return (Expr *) result;
}
/*
* expression_planner_with_deps
* Perform planner's transformations on a standalone expression,
* returning expression dependency information along with the result.
*
* This is identical to expression_planner() except that it also returns
* information about possible dependencies of the expression, ie identities of
* objects whose definitions affect the result. As in a PlannedStmt, these
* are expressed as a list of relation Oids and a list of PlanInvalItems.
*/
Expr *
expression_planner_with_deps(Expr *expr,
List **relationOids,
List **invalItems)
{
Node *result;
PlannerGlobal glob;
PlannerInfo root;
/* Make up dummy planner state so we can use setrefs machinery */
MemSet(&glob, 0, sizeof(glob));
glob.type = T_PlannerGlobal;
glob.relationOids = NIL;
glob.invalItems = NIL;
MemSet(&root, 0, sizeof(root));
root.type = T_PlannerInfo;
root.glob = &glob;
/*
* Convert named-argument function calls, insert default arguments and
* simplify constant subexprs. Collect identities of inlined functions
* and elided domains, too.
*/
result = eval_const_expressions(&root, (Node *) expr);
/* Fill in opfuncid values if missing */
fix_opfuncids(result);
/*
* Now walk the finished expression to find anything else we ought to
* record as an expression dependency.
*/
(void) extract_query_dependencies_walker(result, &root);
*relationOids = glob.relationOids;
*invalItems = glob.invalItems;
return (Expr *) result;
}
/*
* plan_cluster_use_sort
* Use the planner to decide how CLUSTER should implement sorting
*
* tableOid is the OID of a table to be clustered on its index indexOid
* (which is already known to be a btree index). Decide whether it's
* cheaper to do an indexscan or a seqscan-plus-sort to execute the CLUSTER.
* Return true to use sorting, false to use an indexscan.
*
* Note: caller had better already hold some type of lock on the table.
*/
bool
plan_cluster_use_sort(Oid tableOid, Oid indexOid)
{
PlannerInfo *root;
Query *query;
PlannerGlobal *glob;
RangeTblEntry *rte;
RelOptInfo *rel;
IndexOptInfo *indexInfo;
QualCost indexExprCost;
Cost comparisonCost;
Path *seqScanPath;
Path seqScanAndSortPath;
IndexPath *indexScanPath;
ListCell *lc;
/* We can short-circuit the cost comparison if indexscans are disabled */
if (!enable_indexscan)
return true; /* use sort */
/* Set up mostly-dummy planner state */
query = makeNode(Query);
query->commandType = CMD_SELECT;
glob = makeNode(PlannerGlobal);
root = makeNode(PlannerInfo);
root->parse = query;
root->glob = glob;
root->query_level = 1;
root->planner_cxt = CurrentMemoryContext;
root->wt_param_id = -1;
/* Build a minimal RTE for the rel */
rte = makeNode(RangeTblEntry);
rte->rtekind = RTE_RELATION;
rte->relid = tableOid;
rte->relkind = RELKIND_RELATION; /* Don't be too picky. */
rte->rellockmode = AccessShareLock;
rte->lateral = false;
rte->inh = false;
rte->inFromCl = true;
query->rtable = list_make1(rte);
/* Set up RTE/RelOptInfo arrays */
setup_simple_rel_arrays(root);
/* Build RelOptInfo */
rel = build_simple_rel(root, 1, NULL);
/* Locate IndexOptInfo for the target index */
indexInfo = NULL;
foreach(lc, rel->indexlist)
{
indexInfo = lfirst_node(IndexOptInfo, lc);
if (indexInfo->indexoid == indexOid)
break;
}
/*
* It's possible that get_relation_info did not generate an IndexOptInfo
* for the desired index; this could happen if it's not yet reached its
* indcheckxmin usability horizon, or if it's a system index and we're
* ignoring system indexes. In such cases we should tell CLUSTER to not
* trust the index contents but use seqscan-and-sort.
*/
if (lc == NULL) /* not in the list? */
return true; /* use sort */
/*
* Rather than doing all the pushups that would be needed to use
* set_baserel_size_estimates, just do a quick hack for rows and width.
*/
rel->rows = rel->tuples;
rel->reltarget->width = get_relation_data_width(tableOid, NULL);
root->total_table_pages = rel->pages;
/*
* Determine eval cost of the index expressions, if any. We need to
* charge twice that amount for each tuple comparison that happens during
* the sort, since tuplesort.c will have to re-evaluate the index
* expressions each time. (XXX that's pretty inefficient...)
*/
cost_qual_eval(&indexExprCost, indexInfo->indexprs, root);
comparisonCost = 2.0 * (indexExprCost.startup + indexExprCost.per_tuple);
/* Estimate the cost of seq scan + sort */
seqScanPath = create_seqscan_path(root, rel, NULL, 0);
cost_sort(&seqScanAndSortPath, root, NIL,
seqScanPath->total_cost, rel->tuples, rel->reltarget->width,
comparisonCost, maintenance_work_mem, -1.0);
/* Estimate the cost of index scan */
indexScanPath = create_index_path(root, indexInfo,
NIL, NIL, NIL, NIL,
ForwardScanDirection, false,
NULL, 1.0, false);
return (seqScanAndSortPath.total_cost < indexScanPath->path.total_cost);
}
/*
* plan_create_index_workers
* Use the planner to decide how many parallel worker processes
* CREATE INDEX should request for use
*
* tableOid is the table on which the index is to be built. indexOid is the
* OID of an index to be created or reindexed (which must be a btree index).
*
* Return value is the number of parallel worker processes to request. It
* may be unsafe to proceed if this is 0. Note that this does not include the
* leader participating as a worker (value is always a number of parallel
* worker processes).
*
* Note: caller had better already hold some type of lock on the table and
* index.
*/
int
plan_create_index_workers(Oid tableOid, Oid indexOid)
{
PlannerInfo *root;
Query *query;
PlannerGlobal *glob;
RangeTblEntry *rte;
Relation heap;
Relation index;
RelOptInfo *rel;
int parallel_workers;
BlockNumber heap_blocks;
double reltuples;
double allvisfrac;
/*
* We don't allow performing parallel operation in standalone backend or
* when parallelism is disabled.
*/
if (!IsUnderPostmaster || max_parallel_maintenance_workers == 0)
return 0;
/* Set up largely-dummy planner state */
query = makeNode(Query);
query->commandType = CMD_SELECT;
glob = makeNode(PlannerGlobal);
root = makeNode(PlannerInfo);
root->parse = query;
root->glob = glob;
root->query_level = 1;
root->planner_cxt = CurrentMemoryContext;
root->wt_param_id = -1;
/*
* Build a minimal RTE.
*
* Mark the RTE with inh = true. This is a kludge to prevent
* get_relation_info() from fetching index info, which is necessary
* because it does not expect that any IndexOptInfo is currently
* undergoing REINDEX.
*/
rte = makeNode(RangeTblEntry);
rte->rtekind = RTE_RELATION;
rte->relid = tableOid;
rte->relkind = RELKIND_RELATION; /* Don't be too picky. */
rte->rellockmode = AccessShareLock;
rte->lateral = false;
rte->inh = true;
rte->inFromCl = true;
query->rtable = list_make1(rte);
/* Set up RTE/RelOptInfo arrays */
setup_simple_rel_arrays(root);
/* Build RelOptInfo */
rel = build_simple_rel(root, 1, NULL);
/* Rels are assumed already locked by the caller */
heap = table_open(tableOid, NoLock);
index = index_open(indexOid, NoLock);
/*
* Determine if it's safe to proceed.
*
* Currently, parallel workers can't access the leader's temporary tables.
* Furthermore, any index predicate or index expressions must be parallel
* safe.
*/
if (heap->rd_rel->relpersistence == RELPERSISTENCE_TEMP ||
!is_parallel_safe(root, (Node *) RelationGetIndexExpressions(index)) ||
!is_parallel_safe(root, (Node *) RelationGetIndexPredicate(index)))
{
parallel_workers = 0;
goto done;
}
/*
* If parallel_workers storage parameter is set for the table, accept that
* as the number of parallel worker processes to launch (though still cap
* at max_parallel_maintenance_workers). Note that we deliberately do not
* consider any other factor when parallel_workers is set. (e.g., memory
* use by workers.)
*/
if (rel->rel_parallel_workers != -1)
{
parallel_workers = Min(rel->rel_parallel_workers,
max_parallel_maintenance_workers);
goto done;
}
/*
* Estimate heap relation size ourselves, since rel->pages cannot be
* trusted (heap RTE was marked as inheritance parent)
*/
estimate_rel_size(heap, NULL, &heap_blocks, &reltuples, &allvisfrac);
/*
* Determine number of workers to scan the heap relation using generic
* model
*/
parallel_workers = compute_parallel_worker(rel, heap_blocks, -1,
max_parallel_maintenance_workers);
/*
* Cap workers based on available maintenance_work_mem as needed.
*
* Note that each tuplesort participant receives an even share of the
* total maintenance_work_mem budget. Aim to leave participants
* (including the leader as a participant) with no less than 32MB of
* memory. This leaves cases where maintenance_work_mem is set to 64MB
* immediately past the threshold of being capable of launching a single
* parallel worker to sort.
*/
while (parallel_workers > 0 &&
maintenance_work_mem / (parallel_workers + 1) < 32768L)
parallel_workers--;
done:
index_close(index, NoLock);
table_close(heap, NoLock);
return parallel_workers;
}
/*
* add_paths_to_grouping_rel
*
* Add non-partial paths to grouping relation.
*/
static void
add_paths_to_grouping_rel(PlannerInfo *root, RelOptInfo *input_rel,
RelOptInfo *grouped_rel,
RelOptInfo *partially_grouped_rel,
const AggClauseCosts *agg_costs,
grouping_sets_data *gd, double dNumGroups,
GroupPathExtraData *extra)
{
Query *parse = root->parse;
Path *cheapest_path = input_rel->cheapest_total_path;
ListCell *lc;
bool can_hash = (extra->flags & GROUPING_CAN_USE_HASH) != 0;
bool can_sort = (extra->flags & GROUPING_CAN_USE_SORT) != 0;
List *havingQual = (List *) extra->havingQual;
AggClauseCosts *agg_final_costs = &extra->agg_final_costs;
if (can_sort)
{
/*
* Use any available suitably-sorted path as input, and also consider
* sorting the cheapest-total path.
*/
foreach(lc, input_rel->pathlist)
{
Path *path = (Path *) lfirst(lc);
Path *path_original = path;
bool is_sorted;
int presorted_keys;
is_sorted = pathkeys_count_contained_in(root->group_pathkeys,
path->pathkeys,
&presorted_keys);
if (path == cheapest_path || is_sorted)
{
/* Sort the cheapest-total path if it isn't already sorted */
if (!is_sorted)
path = (Path *) create_sort_path(root,
grouped_rel,
path,
root->group_pathkeys,
-1.0);
/* Now decide what to stick atop it */
if (parse->groupingSets)
{
consider_groupingsets_paths(root, grouped_rel,
path, true, can_hash,
gd, agg_costs, dNumGroups);
}
else if (parse->hasAggs)
{
/*
* We have aggregation, possibly with plain GROUP BY. Make
* an AggPath.
*/
add_path(grouped_rel, (Path *)
create_agg_path(root,
grouped_rel,
path,
grouped_rel->reltarget,
parse->groupClause ? AGG_SORTED : AGG_PLAIN,
AGGSPLIT_SIMPLE,
parse->groupClause,
havingQual,
agg_costs,
dNumGroups));
}
else if (parse->groupClause)
{
/*
* We have GROUP BY without aggregation or grouping sets.
* Make a GroupPath.
*/
add_path(grouped_rel, (Path *)
create_group_path(root,
grouped_rel,
path,
parse->groupClause,
havingQual,
dNumGroups));
}
else
{
/* Other cases should have been handled above */
Assert(false);
}
}
/*
* Now we may consider incremental sort on this path, but only
* when the path is not already sorted and when incremental sort
* is enabled.
*/
if (is_sorted || !enable_incremental_sort)
continue;
/* Restore the input path (we might have added Sort on top). */
path = path_original;
/* no shared prefix, no point in building incremental sort */
if (presorted_keys == 0)
continue;
/*
* We should have already excluded pathkeys of length 1 because
* then presorted_keys > 0 would imply is_sorted was true.
*/
Assert(list_length(root->group_pathkeys) != 1);
path = (Path *) create_incremental_sort_path(root,
grouped_rel,
path,
root->group_pathkeys,
presorted_keys,
-1.0);
/* Now decide what to stick atop it */
if (parse->groupingSets)
{
consider_groupingsets_paths(root, grouped_rel,
path, true, can_hash,
gd, agg_costs, dNumGroups);
}
else if (parse->hasAggs)
{
/*
* We have aggregation, possibly with plain GROUP BY. Make an
* AggPath.
*/
add_path(grouped_rel, (Path *)
create_agg_path(root,
grouped_rel,
path,
grouped_rel->reltarget,
parse->groupClause ? AGG_SORTED : AGG_PLAIN,
AGGSPLIT_SIMPLE,
parse->groupClause,
havingQual,
agg_costs,
dNumGroups));
}
else if (parse->groupClause)
{
/*
* We have GROUP BY without aggregation or grouping sets. Make
* a GroupPath.
*/
add_path(grouped_rel, (Path *)
create_group_path(root,
grouped_rel,
path,
parse->groupClause,
havingQual,
dNumGroups));
}
else
{
/* Other cases should have been handled above */
Assert(false);
}
}
/*
* Instead of operating directly on the input relation, we can
* consider finalizing a partially aggregated path.
*/
if (partially_grouped_rel != NULL)
{
foreach(lc, partially_grouped_rel->pathlist)
{
Path *path = (Path *) lfirst(lc);
Path *path_original = path;
bool is_sorted;
int presorted_keys;
is_sorted = pathkeys_count_contained_in(root->group_pathkeys,
path->pathkeys,
&presorted_keys);
/*
* Insert a Sort node, if required. But there's no point in
* sorting anything but the cheapest path.
*/
if (!is_sorted)
{
if (path != partially_grouped_rel->cheapest_total_path)
continue;
path = (Path *) create_sort_path(root,
grouped_rel,
path,
root->group_pathkeys,
-1.0);
}
if (parse->hasAggs)
add_path(grouped_rel, (Path *)
create_agg_path(root,
grouped_rel,
path,
grouped_rel->reltarget,
parse->groupClause ? AGG_SORTED : AGG_PLAIN,
AGGSPLIT_FINAL_DESERIAL,
parse->groupClause,
havingQual,
agg_final_costs,
dNumGroups));
else
add_path(grouped_rel, (Path *)
create_group_path(root,
grouped_rel,
path,
parse->groupClause,
havingQual,
dNumGroups));
/*
* Now we may consider incremental sort on this path, but only
* when the path is not already sorted and when incremental
* sort is enabled.
*/
if (is_sorted || !enable_incremental_sort)
continue;
/* Restore the input path (we might have added Sort on top). */
path = path_original;
/* no shared prefix, not point in building incremental sort */
if (presorted_keys == 0)
continue;
/*
* We should have already excluded pathkeys of length 1
* because then presorted_keys > 0 would imply is_sorted was
* true.
*/
Assert(list_length(root->group_pathkeys) != 1);
path = (Path *) create_incremental_sort_path(root,
grouped_rel,
path,
root->group_pathkeys,
presorted_keys,
-1.0);
if (parse->hasAggs)
add_path(grouped_rel, (Path *)
create_agg_path(root,
grouped_rel,
path,
grouped_rel->reltarget,
parse->groupClause ? AGG_SORTED : AGG_PLAIN,
AGGSPLIT_FINAL_DESERIAL,
parse->groupClause,
havingQual,
agg_final_costs,
dNumGroups));
else
add_path(grouped_rel, (Path *)
create_group_path(root,
grouped_rel,
path,
parse->groupClause,
havingQual,
dNumGroups));
}
}
}
if (can_hash)
{
if (parse->groupingSets)
{
/*
* Try for a hash-only groupingsets path over unsorted input.
*/
consider_groupingsets_paths(root, grouped_rel,
cheapest_path, false, true,
gd, agg_costs, dNumGroups);
}
else
{
/*
* Generate a HashAgg Path. We just need an Agg over the
* cheapest-total input path, since input order won't matter.
*/
add_path(grouped_rel, (Path *)
create_agg_path(root, grouped_rel,
cheapest_path,
grouped_rel->reltarget,
AGG_HASHED,
AGGSPLIT_SIMPLE,
parse->groupClause,
havingQual,
agg_costs,
dNumGroups));
}
/*
* Generate a Finalize HashAgg Path atop of the cheapest partially
* grouped path, assuming there is one
*/
if (partially_grouped_rel && partially_grouped_rel->pathlist)
{
Path *path = partially_grouped_rel->cheapest_total_path;
add_path(grouped_rel, (Path *)
create_agg_path(root,
grouped_rel,
path,
grouped_rel->reltarget,
AGG_HASHED,
AGGSPLIT_FINAL_DESERIAL,
parse->groupClause,
havingQual,
agg_final_costs,
dNumGroups));
}
}
/*
* When partitionwise aggregate is used, we might have fully aggregated
* paths in the partial pathlist, because add_paths_to_append_rel() will
* consider a path for grouped_rel consisting of a Parallel Append of
* non-partial paths from each child.
*/
if (grouped_rel->partial_pathlist != NIL)
gather_grouping_paths(root, grouped_rel);
}
/*
* create_partial_grouping_paths
*
* Create a new upper relation representing the result of partial aggregation
* and populate it with appropriate paths. Note that we don't finalize the
* lists of paths here, so the caller can add additional partial or non-partial
* paths and must afterward call gather_grouping_paths and set_cheapest on
* the returned upper relation.
*
* All paths for this new upper relation -- both partial and non-partial --
* have been partially aggregated but require a subsequent FinalizeAggregate
* step.
*
* NB: This function is allowed to return NULL if it determines that there is
* no real need to create a new RelOptInfo.
*/
static RelOptInfo *
create_partial_grouping_paths(PlannerInfo *root,
RelOptInfo *grouped_rel,
RelOptInfo *input_rel,
grouping_sets_data *gd,
GroupPathExtraData *extra,
bool force_rel_creation)
{
Query *parse = root->parse;
RelOptInfo *partially_grouped_rel;
AggClauseCosts *agg_partial_costs = &extra->agg_partial_costs;
AggClauseCosts *agg_final_costs = &extra->agg_final_costs;
Path *cheapest_partial_path = NULL;
Path *cheapest_total_path = NULL;
double dNumPartialGroups = 0;
double dNumPartialPartialGroups = 0;
ListCell *lc;
bool can_hash = (extra->flags & GROUPING_CAN_USE_HASH) != 0;
bool can_sort = (extra->flags & GROUPING_CAN_USE_SORT) != 0;
/*
* Consider whether we should generate partially aggregated non-partial
* paths. We can only do this if we have a non-partial path, and only if
* the parent of the input rel is performing partial partitionwise
* aggregation. (Note that extra->patype is the type of partitionwise
* aggregation being used at the parent level, not this level.)
*/
if (input_rel->pathlist != NIL &&
extra->patype == PARTITIONWISE_AGGREGATE_PARTIAL)
cheapest_total_path = input_rel->cheapest_total_path;
/*
* If parallelism is possible for grouped_rel, then we should consider
* generating partially-grouped partial paths. However, if the input rel
* has no partial paths, then we can't.
*/
if (grouped_rel->consider_parallel && input_rel->partial_pathlist != NIL)
cheapest_partial_path = linitial(input_rel->partial_pathlist);
/*
* If we can't partially aggregate partial paths, and we can't partially
* aggregate non-partial paths, then don't bother creating the new
* RelOptInfo at all, unless the caller specified force_rel_creation.
*/
if (cheapest_total_path == NULL &&
cheapest_partial_path == NULL &&
!force_rel_creation)
return NULL;
/*
* Build a new upper relation to represent the result of partially
* aggregating the rows from the input relation.
*/
partially_grouped_rel = fetch_upper_rel(root,
UPPERREL_PARTIAL_GROUP_AGG,
grouped_rel->relids);
partially_grouped_rel->consider_parallel =
grouped_rel->consider_parallel;
partially_grouped_rel->reloptkind = grouped_rel->reloptkind;
partially_grouped_rel->serverid = grouped_rel->serverid;
partially_grouped_rel->userid = grouped_rel->userid;
partially_grouped_rel->useridiscurrent = grouped_rel->useridiscurrent;
partially_grouped_rel->fdwroutine = grouped_rel->fdwroutine;
/*
* Build target list for partial aggregate paths. These paths cannot just
* emit the same tlist as regular aggregate paths, because (1) we must
* include Vars and Aggrefs needed in HAVING, which might not appear in
* the result tlist, and (2) the Aggrefs must be set in partial mode.
*/
partially_grouped_rel->reltarget =
make_partial_grouping_target(root, grouped_rel->reltarget,
extra->havingQual);
if (!extra->partial_costs_set)
{
/*
* Collect statistics about aggregates for estimating costs of
* performing aggregation in parallel.
*/
MemSet(agg_partial_costs, 0, sizeof(AggClauseCosts));
MemSet(agg_final_costs, 0, sizeof(AggClauseCosts));
if (parse->hasAggs)
{
/* partial phase */
get_agg_clause_costs(root, AGGSPLIT_INITIAL_SERIAL,
agg_partial_costs);
/* final phase */
get_agg_clause_costs(root, AGGSPLIT_FINAL_DESERIAL,
agg_final_costs);
}
extra->partial_costs_set = true;
}
/* Estimate number of partial groups. */
if (cheapest_total_path != NULL)
dNumPartialGroups =
get_number_of_groups(root,
cheapest_total_path->rows,
gd,
extra->targetList);
if (cheapest_partial_path != NULL)
dNumPartialPartialGroups =
get_number_of_groups(root,
cheapest_partial_path->rows,
gd,
extra->targetList);
if (can_sort && cheapest_total_path != NULL)
{
/* This should have been checked previously */
Assert(parse->hasAggs || parse->groupClause);
/*
* Use any available suitably-sorted path as input, and also consider
* sorting the cheapest partial path.
*/
foreach(lc, input_rel->pathlist)
{
Path *path = (Path *) lfirst(lc);
bool is_sorted;
is_sorted = pathkeys_contained_in(root->group_pathkeys,
path->pathkeys);
if (path == cheapest_total_path || is_sorted)
{
/* Sort the cheapest partial path, if it isn't already */
if (!is_sorted)
path = (Path *) create_sort_path(root,
partially_grouped_rel,
path,
root->group_pathkeys,
-1.0);
if (parse->hasAggs)
add_path(partially_grouped_rel, (Path *)
create_agg_path(root,
partially_grouped_rel,
path,
partially_grouped_rel->reltarget,
parse->groupClause ? AGG_SORTED : AGG_PLAIN,
AGGSPLIT_INITIAL_SERIAL,
parse->groupClause,
NIL,
agg_partial_costs,
dNumPartialGroups));
else
add_path(partially_grouped_rel, (Path *)
create_group_path(root,
partially_grouped_rel,
path,
parse->groupClause,
NIL,
dNumPartialGroups));
}
}
/*
* Consider incremental sort on all partial paths, if enabled.
*
* We can also skip the entire loop when we only have a single-item
* group_pathkeys because then we can't possibly have a presorted
* prefix of the list without having the list be fully sorted.
*/
if (enable_incremental_sort && list_length(root->group_pathkeys) > 1)
{
foreach(lc, input_rel->pathlist)
{
Path *path = (Path *) lfirst(lc);
bool is_sorted;
int presorted_keys;
is_sorted = pathkeys_count_contained_in(root->group_pathkeys,
path->pathkeys,
&presorted_keys);
/* Ignore already sorted paths */
if (is_sorted)
continue;
if (presorted_keys == 0)
continue;
/* Since we have presorted keys, consider incremental sort. */
path = (Path *) create_incremental_sort_path(root,
partially_grouped_rel,
path,
root->group_pathkeys,
presorted_keys,
-1.0);
if (parse->hasAggs)
add_path(partially_grouped_rel, (Path *)
create_agg_path(root,
partially_grouped_rel,
path,
partially_grouped_rel->reltarget,
parse->groupClause ? AGG_SORTED : AGG_PLAIN,
AGGSPLIT_INITIAL_SERIAL,
parse->groupClause,
NIL,
agg_partial_costs,
dNumPartialGroups));
else
add_path(partially_grouped_rel, (Path *)
create_group_path(root,
partially_grouped_rel,
path,
parse->groupClause,
NIL,
dNumPartialGroups));
}
}
}
if (can_sort && cheapest_partial_path != NULL)
{
/* Similar to above logic, but for partial paths. */
foreach(lc, input_rel->partial_pathlist)
{
Path *path = (Path *) lfirst(lc);
Path *path_original = path;
bool is_sorted;
int presorted_keys;
is_sorted = pathkeys_count_contained_in(root->group_pathkeys,
path->pathkeys,
&presorted_keys);
if (path == cheapest_partial_path || is_sorted)
{
/* Sort the cheapest partial path, if it isn't already */
if (!is_sorted)
path = (Path *) create_sort_path(root,
partially_grouped_rel,
path,
root->group_pathkeys,
-1.0);
if (parse->hasAggs)
add_partial_path(partially_grouped_rel, (Path *)
create_agg_path(root,
partially_grouped_rel,
path,
partially_grouped_rel->reltarget,
parse->groupClause ? AGG_SORTED : AGG_PLAIN,
AGGSPLIT_INITIAL_SERIAL,
parse->groupClause,
NIL,
agg_partial_costs,
dNumPartialPartialGroups));
else
add_partial_path(partially_grouped_rel, (Path *)
create_group_path(root,
partially_grouped_rel,
path,
parse->groupClause,
NIL,
dNumPartialPartialGroups));
}
/*
* Now we may consider incremental sort on this path, but only
* when the path is not already sorted and when incremental sort
* is enabled.
*/
if (is_sorted || !enable_incremental_sort)
continue;
/* Restore the input path (we might have added Sort on top). */
path = path_original;
/* no shared prefix, not point in building incremental sort */
if (presorted_keys == 0)
continue;
/*
* We should have already excluded pathkeys of length 1 because
* then presorted_keys > 0 would imply is_sorted was true.
*/
Assert(list_length(root->group_pathkeys) != 1);
path = (Path *) create_incremental_sort_path(root,
partially_grouped_rel,
path,
root->group_pathkeys,
presorted_keys,
-1.0);
if (parse->hasAggs)
add_partial_path(partially_grouped_rel, (Path *)
create_agg_path(root,
partially_grouped_rel,
path,
partially_grouped_rel->reltarget,
parse->groupClause ? AGG_SORTED : AGG_PLAIN,
AGGSPLIT_INITIAL_SERIAL,
parse->groupClause,
NIL,
agg_partial_costs,
dNumPartialPartialGroups));
else
add_partial_path(partially_grouped_rel, (Path *)
create_group_path(root,
partially_grouped_rel,
path,
parse->groupClause,
NIL,
dNumPartialPartialGroups));
}
}
/*
* Add a partially-grouped HashAgg Path where possible
*/
if (can_hash && cheapest_total_path != NULL)
{
/* Checked above */
Assert(parse->hasAggs || parse->groupClause);
add_path(partially_grouped_rel, (Path *)
create_agg_path(root,
partially_grouped_rel,
cheapest_total_path,
partially_grouped_rel->reltarget,
AGG_HASHED,
AGGSPLIT_INITIAL_SERIAL,
parse->groupClause,
NIL,
agg_partial_costs,
dNumPartialGroups));
}
/*
* Now add a partially-grouped HashAgg partial Path where possible
*/
if (can_hash && cheapest_partial_path != NULL)
{
add_partial_path(partially_grouped_rel, (Path *)
create_agg_path(root,
partially_grouped_rel,
cheapest_partial_path,
partially_grouped_rel->reltarget,
AGG_HASHED,
AGGSPLIT_INITIAL_SERIAL,
parse->groupClause,
NIL,
agg_partial_costs,
dNumPartialPartialGroups));
}
/*
* If there is an FDW that's responsible for all baserels of the query,
* let it consider adding partially grouped ForeignPaths.
*/
if (partially_grouped_rel->fdwroutine &&
partially_grouped_rel->fdwroutine->GetForeignUpperPaths)
{
FdwRoutine *fdwroutine = partially_grouped_rel->fdwroutine;
fdwroutine->GetForeignUpperPaths(root,
UPPERREL_PARTIAL_GROUP_AGG,
input_rel, partially_grouped_rel,
extra);
}
return partially_grouped_rel;
}
/*
* Generate Gather and Gather Merge paths for a grouping relation or partial
* grouping relation.
*
* generate_useful_gather_paths does most of the work, but we also consider a
* special case: we could try sorting the data by the group_pathkeys and then
* applying Gather Merge.
*
* NB: This function shouldn't be used for anything other than a grouped or
* partially grouped relation not only because of the fact that it explicitly
* references group_pathkeys but we pass "true" as the third argument to
* generate_useful_gather_paths().
*/
static void
gather_grouping_paths(PlannerInfo *root, RelOptInfo *rel)
{
ListCell *lc;
Path *cheapest_partial_path;
/* Try Gather for unordered paths and Gather Merge for ordered ones. */
generate_useful_gather_paths(root, rel, true);
/* Try cheapest partial path + explicit Sort + Gather Merge. */
cheapest_partial_path = linitial(rel->partial_pathlist);
if (!pathkeys_contained_in(root->group_pathkeys,
cheapest_partial_path->pathkeys))
{
Path *path;
double total_groups;
total_groups =
cheapest_partial_path->rows * cheapest_partial_path->parallel_workers;
path = (Path *) create_sort_path(root, rel, cheapest_partial_path,
root->group_pathkeys,
-1.0);
path = (Path *)
create_gather_merge_path(root,
rel,
path,
rel->reltarget,
root->group_pathkeys,
NULL,
&total_groups);
add_path(rel, path);
}
/*
* Consider incremental sort on all partial paths, if enabled.
*
* We can also skip the entire loop when we only have a single-item
* group_pathkeys because then we can't possibly have a presorted prefix
* of the list without having the list be fully sorted.
*/
if (!enable_incremental_sort || list_length(root->group_pathkeys) == 1)
return;
/* also consider incremental sort on partial paths, if enabled */
foreach(lc, rel->partial_pathlist)
{
Path *path = (Path *) lfirst(lc);
bool is_sorted;
int presorted_keys;
double total_groups;
is_sorted = pathkeys_count_contained_in(root->group_pathkeys,
path->pathkeys,
&presorted_keys);
if (is_sorted)
continue;
if (presorted_keys == 0)
continue;
path = (Path *) create_incremental_sort_path(root,
rel,
path,
root->group_pathkeys,
presorted_keys,
-1.0);
path = (Path *)
create_gather_merge_path(root,
rel,
path,
rel->reltarget,
root->group_pathkeys,
NULL,
&total_groups);
add_path(rel, path);
}
}
/*
* can_partial_agg
*
* Determines whether or not partial grouping and/or aggregation is possible.
* Returns true when possible, false otherwise.
*/
static bool
can_partial_agg(PlannerInfo *root)
{
Query *parse = root->parse;
if (!parse->hasAggs && parse->groupClause == NIL)
{
/*
* We don't know how to do parallel aggregation unless we have either
* some aggregates or a grouping clause.
*/
return false;
}
else if (parse->groupingSets)
{
/* We don't know how to do grouping sets in parallel. */
return false;
}
else if (root->hasNonPartialAggs || root->hasNonSerialAggs)
{
/* Insufficient support for partial mode. */
return false;
}
/* Everything looks good. */
return true;
}
/*
* apply_scanjoin_target_to_paths
*
* Adjust the final scan/join relation, and recursively all of its children,
* to generate the final scan/join target. It would be more correct to model
* this as a separate planning step with a new RelOptInfo at the toplevel and
* for each child relation, but doing it this way is noticeably cheaper.
* Maybe that problem can be solved at some point, but for now we do this.
*
* If tlist_same_exprs is true, then the scan/join target to be applied has
* the same expressions as the existing reltarget, so we need only insert the
* appropriate sortgroupref information. By avoiding the creation of
* projection paths we save effort both immediately and at plan creation time.
*/
static void
apply_scanjoin_target_to_paths(PlannerInfo *root,
RelOptInfo *rel,
List *scanjoin_targets,
List *scanjoin_targets_contain_srfs,
bool scanjoin_target_parallel_safe,
bool tlist_same_exprs)
{
bool rel_is_partitioned = IS_PARTITIONED_REL(rel);
PathTarget *scanjoin_target;
ListCell *lc;
/* This recurses, so be paranoid. */
check_stack_depth();
/*
* If the rel is partitioned, we want to drop its existing paths and
* generate new ones. This function would still be correct if we kept the
* existing paths: we'd modify them to generate the correct target above
* the partitioning Append, and then they'd compete on cost with paths
* generating the target below the Append. However, in our current cost
* model the latter way is always the same or cheaper cost, so modifying
* the existing paths would just be useless work. Moreover, when the cost
* is the same, varying roundoff errors might sometimes allow an existing
* path to be picked, resulting in undesirable cross-platform plan
* variations. So we drop old paths and thereby force the work to be done
* below the Append, except in the case of a non-parallel-safe target.
*
* Some care is needed, because we have to allow
* generate_useful_gather_paths to see the old partial paths in the next
* stanza. Hence, zap the main pathlist here, then allow
* generate_useful_gather_paths to add path(s) to the main list, and
* finally zap the partial pathlist.
*/
if (rel_is_partitioned)
rel->pathlist = NIL;
/*
* If the scan/join target is not parallel-safe, partial paths cannot
* generate it.
*/
if (!scanjoin_target_parallel_safe)
{
/*
* Since we can't generate the final scan/join target in parallel
* workers, this is our last opportunity to use any partial paths that
* exist; so build Gather path(s) that use them and emit whatever the
* current reltarget is. We don't do this in the case where the
* target is parallel-safe, since we will be able to generate superior
* paths by doing it after the final scan/join target has been
* applied.
*/
generate_useful_gather_paths(root, rel, false);
/* Can't use parallel query above this level. */
rel->partial_pathlist = NIL;
rel->consider_parallel = false;
}
/* Finish dropping old paths for a partitioned rel, per comment above */
if (rel_is_partitioned)
rel->partial_pathlist = NIL;
/* Extract SRF-free scan/join target. */
scanjoin_target = linitial_node(PathTarget, scanjoin_targets);
/*
* Apply the SRF-free scan/join target to each existing path.
*
* If the tlist exprs are the same, we can just inject the sortgroupref
* information into the existing pathtargets. Otherwise, replace each
* path with a projection path that generates the SRF-free scan/join
* target. This can't change the ordering of paths within rel->pathlist,
* so we just modify the list in place.
*/
foreach(lc, rel->pathlist)
{
Path *subpath = (Path *) lfirst(lc);
/* Shouldn't have any parameterized paths anymore */
Assert(subpath->param_info == NULL);
if (tlist_same_exprs)
subpath->pathtarget->sortgrouprefs =
scanjoin_target->sortgrouprefs;
else
{
Path *newpath;
newpath = (Path *) create_projection_path(root, rel, subpath,
scanjoin_target);
lfirst(lc) = newpath;
}
}
/* Likewise adjust the targets for any partial paths. */
foreach(lc, rel->partial_pathlist)
{
Path *subpath = (Path *) lfirst(lc);
/* Shouldn't have any parameterized paths anymore */
Assert(subpath->param_info == NULL);
if (tlist_same_exprs)
subpath->pathtarget->sortgrouprefs =
scanjoin_target->sortgrouprefs;
else
{
Path *newpath;
newpath = (Path *) create_projection_path(root, rel, subpath,
scanjoin_target);
lfirst(lc) = newpath;
}
}
/*
* Now, if final scan/join target contains SRFs, insert ProjectSetPath(s)
* atop each existing path. (Note that this function doesn't look at the
* cheapest-path fields, which is a good thing because they're bogus right
* now.)
*/
if (root->parse->hasTargetSRFs)
adjust_paths_for_srfs(root, rel,
scanjoin_targets,
scanjoin_targets_contain_srfs);
/*
* Update the rel's target to be the final (with SRFs) scan/join target.
* This now matches the actual output of all the paths, and we might get
* confused in createplan.c if they don't agree. We must do this now so
* that any append paths made in the next part will use the correct
* pathtarget (cf. create_append_path).
*
* Note that this is also necessary if GetForeignUpperPaths() gets called
* on the final scan/join relation or on any of its children, since the
* FDW might look at the rel's target to create ForeignPaths.
*/
rel->reltarget = llast_node(PathTarget, scanjoin_targets);
/*
* If the relation is partitioned, recursively apply the scan/join target
* to all partitions, and generate brand-new Append paths in which the
* scan/join target is computed below the Append rather than above it.
* Since Append is not projection-capable, that might save a separate
* Result node, and it also is important for partitionwise aggregate.
*/
if (rel_is_partitioned)
{
List *live_children = NIL;
int partition_idx;
/* Adjust each partition. */
for (partition_idx = 0; partition_idx < rel->nparts; partition_idx++)
{
RelOptInfo *child_rel = rel->part_rels[partition_idx];
AppendRelInfo **appinfos;
int nappinfos;
List *child_scanjoin_targets = NIL;
ListCell *lc;
/* Pruned or dummy children can be ignored. */
if (child_rel == NULL || IS_DUMMY_REL(child_rel))
continue;
/* Translate scan/join targets for this child. */
appinfos = find_appinfos_by_relids(root, child_rel->relids,
&nappinfos);
foreach(lc, scanjoin_targets)
{
PathTarget *target = lfirst_node(PathTarget, lc);
target = copy_pathtarget(target);
target->exprs = (List *)
adjust_appendrel_attrs(root,
(Node *) target->exprs,
nappinfos, appinfos);
child_scanjoin_targets = lappend(child_scanjoin_targets,
target);
}
pfree(appinfos);
/* Recursion does the real work. */
apply_scanjoin_target_to_paths(root, child_rel,
child_scanjoin_targets,
scanjoin_targets_contain_srfs,
scanjoin_target_parallel_safe,
tlist_same_exprs);
/* Save non-dummy children for Append paths. */
if (!IS_DUMMY_REL(child_rel))
live_children = lappend(live_children, child_rel);
}
/* Build new paths for this relation by appending child paths. */
add_paths_to_append_rel(root, rel, live_children);
}
/*
* Consider generating Gather or Gather Merge paths. We must only do this
* if the relation is parallel safe, and we don't do it for child rels to
* avoid creating multiple Gather nodes within the same plan. We must do
* this after all paths have been generated and before set_cheapest, since
* one of the generated paths may turn out to be the cheapest one.
*/
if (rel->consider_parallel && !IS_OTHER_REL(rel))
generate_useful_gather_paths(root, rel, false);
/*
* Reassess which paths are the cheapest, now that we've potentially added
* new Gather (or Gather Merge) and/or Append (or MergeAppend) paths to
* this relation.
*/
set_cheapest(rel);
}
/*
* create_partitionwise_grouping_paths
*
* If the partition keys of input relation are part of the GROUP BY clause, all
* the rows belonging to a given group come from a single partition. This
* allows aggregation/grouping over a partitioned relation to be broken down
* into aggregation/grouping on each partition. This should be no worse, and
* often better, than the normal approach.
*
* However, if the GROUP BY clause does not contain all the partition keys,
* rows from a given group may be spread across multiple partitions. In that
* case, we perform partial aggregation for each group, append the results,
* and then finalize aggregation. This is less certain to win than the
* previous case. It may win if the PartialAggregate stage greatly reduces
* the number of groups, because fewer rows will pass through the Append node.
* It may lose if we have lots of small groups.
*/
static void
create_partitionwise_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *grouped_rel,
RelOptInfo *partially_grouped_rel,
const AggClauseCosts *agg_costs,
grouping_sets_data *gd,
PartitionwiseAggregateType patype,
GroupPathExtraData *extra)
{
int nparts = input_rel->nparts;
int cnt_parts;
List *grouped_live_children = NIL;
List *partially_grouped_live_children = NIL;
PathTarget *target = grouped_rel->reltarget;
bool partial_grouping_valid = true;
Assert(patype != PARTITIONWISE_AGGREGATE_NONE);
Assert(patype != PARTITIONWISE_AGGREGATE_PARTIAL ||
partially_grouped_rel != NULL);
/* Add paths for partitionwise aggregation/grouping. */
for (cnt_parts = 0; cnt_parts < nparts; cnt_parts++)
{
RelOptInfo *child_input_rel = input_rel->part_rels[cnt_parts];
PathTarget *child_target = copy_pathtarget(target);
AppendRelInfo **appinfos;
int nappinfos;
GroupPathExtraData child_extra;
RelOptInfo *child_grouped_rel;
RelOptInfo *child_partially_grouped_rel;
/* Pruned or dummy children can be ignored. */
if (child_input_rel == NULL || IS_DUMMY_REL(child_input_rel))
continue;
/*
* Copy the given "extra" structure as is and then override the
* members specific to this child.
*/
memcpy(&child_extra, extra, sizeof(child_extra));
appinfos = find_appinfos_by_relids(root, child_input_rel->relids,
&nappinfos);
child_target->exprs = (List *)
adjust_appendrel_attrs(root,
(Node *) target->exprs,
nappinfos, appinfos);
/* Translate havingQual and targetList. */
child_extra.havingQual = (Node *)
adjust_appendrel_attrs(root,
extra->havingQual,
nappinfos, appinfos);
child_extra.targetList = (List *)
adjust_appendrel_attrs(root,
(Node *) extra->targetList,
nappinfos, appinfos);
/*
* extra->patype was the value computed for our parent rel; patype is
* the value for this relation. For the child, our value is its
* parent rel's value.
*/
child_extra.patype = patype;
/*
* Create grouping relation to hold fully aggregated grouping and/or
* aggregation paths for the child.
*/
child_grouped_rel = make_grouping_rel(root, child_input_rel,
child_target,
extra->target_parallel_safe,
child_extra.havingQual);
/* Create grouping paths for this child relation. */
create_ordinary_grouping_paths(root, child_input_rel,
child_grouped_rel,
agg_costs, gd, &child_extra,
&child_partially_grouped_rel);
if (child_partially_grouped_rel)
{
partially_grouped_live_children =
lappend(partially_grouped_live_children,
child_partially_grouped_rel);
}
else
partial_grouping_valid = false;
if (patype == PARTITIONWISE_AGGREGATE_FULL)
{
set_cheapest(child_grouped_rel);
grouped_live_children = lappend(grouped_live_children,
child_grouped_rel);
}
pfree(appinfos);
}
/*
* Try to create append paths for partially grouped children. For full
* partitionwise aggregation, we might have paths in the partial_pathlist
* if parallel aggregation is possible. For partial partitionwise
* aggregation, we may have paths in both pathlist and partial_pathlist.
*
* NB: We must have a partially grouped path for every child in order to
* generate a partially grouped path for this relation.
*/
if (partially_grouped_rel && partial_grouping_valid)
{
Assert(partially_grouped_live_children != NIL);
add_paths_to_append_rel(root, partially_grouped_rel,
partially_grouped_live_children);
/*
* We need call set_cheapest, since the finalization step will use the
* cheapest path from the rel.
*/
if (partially_grouped_rel->pathlist)
set_cheapest(partially_grouped_rel);
}
/* If possible, create append paths for fully grouped children. */
if (patype == PARTITIONWISE_AGGREGATE_FULL)
{
Assert(grouped_live_children != NIL);
add_paths_to_append_rel(root, grouped_rel, grouped_live_children);
}
}
/*
* group_by_has_partkey
*
* Returns true, if all the partition keys of the given relation are part of
* the GROUP BY clauses, false otherwise.
*/
static bool
group_by_has_partkey(RelOptInfo *input_rel,
List *targetList,
List *groupClause)
{
List *groupexprs = get_sortgrouplist_exprs(groupClause, targetList);
int cnt = 0;
int partnatts;
/* Input relation should be partitioned. */
Assert(input_rel->part_scheme);
/* Rule out early, if there are no partition keys present. */
if (!input_rel->partexprs)
return false;
partnatts = input_rel->part_scheme->partnatts;
for (cnt = 0; cnt < partnatts; cnt++)
{
List *partexprs = input_rel->partexprs[cnt];
ListCell *lc;
bool found = false;
foreach(lc, partexprs)
{
Expr *partexpr = lfirst(lc);
if (list_member(groupexprs, partexpr))
{
found = true;
break;
}
}
/*
* If none of the partition key expressions match with any of the
* GROUP BY expression, return false.
*/
if (!found)
return false;
}
return true;
}