/*-------------------------------------------------------------------------
*
* setrefs.c
* Post-processing of a completed plan tree: fix references to subplan
* vars, and compute regproc values for operators
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.114 2005/09/05 18:59:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "nodes/makefuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/planmain.h"
#include "optimizer/tlist.h"
#include "optimizer/var.h"
#include "parser/parse_expr.h"
#include "parser/parsetree.h"
#include "utils/lsyscache.h"
typedef struct
{
Index varno; /* RT index of Var */
AttrNumber varattno; /* attr number of Var */
AttrNumber resno; /* TLE position of Var */
} tlist_vinfo;
typedef struct
{
List *tlist; /* underlying target list */
int num_vars; /* number of plain Var tlist entries */
bool has_non_vars; /* are there non-plain-Var entries? */
/* array of num_vars entries: */
tlist_vinfo vars[1]; /* VARIABLE LENGTH ARRAY */
} indexed_tlist; /* VARIABLE LENGTH STRUCT */
typedef struct
{
List *rtable;
indexed_tlist *outer_itlist;
indexed_tlist *inner_itlist;
Index acceptable_rel;
} join_references_context;
typedef struct
{
indexed_tlist *subplan_itlist;
Index subvarno;
} replace_vars_with_subplan_refs_context;
static Plan *set_subqueryscan_references(SubqueryScan *plan, List *rtable);
static bool trivial_subqueryscan(SubqueryScan *plan);
static void adjust_plan_varnos(Plan *plan, int rtoffset);
static void adjust_expr_varnos(Node *node, int rtoffset);
static bool adjust_expr_varnos_walker(Node *node, int *context);
static void fix_expr_references(Plan *plan, Node *node);
static bool fix_expr_references_walker(Node *node, void *context);
static void set_join_references(Join *join, List *rtable);
static void set_inner_join_references(Plan *inner_plan,
List *rtable,
indexed_tlist *outer_itlist);
static void set_uppernode_references(Plan *plan, Index subvarno);
static indexed_tlist *build_tlist_index(List *tlist);
static Var *search_indexed_tlist_for_var(Var *var,
indexed_tlist *itlist,
Index newvarno);
static Var *search_indexed_tlist_for_non_var(Node *node,
indexed_tlist *itlist,
Index newvarno);
static List *join_references(List *clauses,
List *rtable,
indexed_tlist *outer_itlist,
indexed_tlist *inner_itlist,
Index acceptable_rel);
static Node *join_references_mutator(Node *node,
join_references_context *context);
static Node *replace_vars_with_subplan_refs(Node *node,
indexed_tlist *subplan_itlist,
Index subvarno);
static Node *replace_vars_with_subplan_refs_mutator(Node *node,
replace_vars_with_subplan_refs_context *context);
static bool fix_opfuncids_walker(Node *node, void *context);
static void set_sa_opfuncid(ScalarArrayOpExpr *opexpr);
/*****************************************************************************
*
* SUBPLAN REFERENCES
*
*****************************************************************************/
/*
* set_plan_references
*
* This is the final processing pass of the planner/optimizer. The plan
* tree is complete; we just have to adjust some representational details
* for the convenience of the executor. We update Vars in upper plan nodes
* to refer to the outputs of their subplans, and we compute regproc OIDs
* for operators (ie, we look up the function that implements each op).
*
* We also perform one final optimization step, which is to delete
* SubqueryScan plan nodes that aren't doing anything useful (ie, have
* no qual and a no-op targetlist). The reason for doing this last is that
* it can't readily be done before set_plan_references, because it would
* break set_uppernode_references: the Vars in the subquery's top tlist
* won't match up with the Vars in the outer plan tree. The SubqueryScan
* serves a necessary function as a buffer between outer query and subquery
* variable numbering ... but the executor doesn't care about that, only the
* planner.
*
* set_plan_references recursively traverses the whole plan tree.
*
* The return value is normally the same Plan node passed in, but can be
* different when the passed-in Plan is a SubqueryScan we decide isn't needed.
*
* Note: to delete a SubqueryScan, we have to renumber Vars in its child nodes
* and append the modified subquery rangetable to the outer rangetable.
* Therefore "rtable" is an in/out argument and really should be declared
* "List **". But in the interest of notational simplicity we don't do that.
* (Since rtable can't be NIL if there's a SubqueryScan, the list header
* address won't change when we append a subquery rangetable.)
*/
Plan *
set_plan_references(Plan *plan, List *rtable)
{
ListCell *l;
if (plan == NULL)
return NULL;
/*
* Plan-type-specific fixes
*/
switch (nodeTag(plan))
{
case T_SeqScan:
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
break;
case T_IndexScan:
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
fix_expr_references(plan,
(Node *) ((IndexScan *) plan)->indexqual);
fix_expr_references(plan,
(Node *) ((IndexScan *) plan)->indexqualorig);
break;
case T_BitmapIndexScan:
/* no need to fix targetlist and qual */
Assert(plan->targetlist == NIL);
Assert(plan->qual == NIL);
fix_expr_references(plan,
(Node *) ((BitmapIndexScan *) plan)->indexqual);
fix_expr_references(plan,
(Node *) ((BitmapIndexScan *) plan)->indexqualorig);
break;
case T_BitmapHeapScan:
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
fix_expr_references(plan,
(Node *) ((BitmapHeapScan *) plan)->bitmapqualorig);
break;
case T_TidScan:
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
fix_expr_references(plan,
(Node *) ((TidScan *) plan)->tideval);
break;
case T_SubqueryScan:
/* Needs special treatment, see comments below */
return set_subqueryscan_references((SubqueryScan *) plan, rtable);
case T_FunctionScan:
{
RangeTblEntry *rte;
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
rte = rt_fetch(((FunctionScan *) plan)->scan.scanrelid,
rtable);
Assert(rte->rtekind == RTE_FUNCTION);
fix_expr_references(plan, rte->funcexpr);
}
break;
case T_NestLoop:
set_join_references((Join *) plan, rtable);
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
fix_expr_references(plan, (Node *) ((Join *) plan)->joinqual);
break;
case T_MergeJoin:
set_join_references((Join *) plan, rtable);
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
fix_expr_references(plan, (Node *) ((Join *) plan)->joinqual);
fix_expr_references(plan,
(Node *) ((MergeJoin *) plan)->mergeclauses);
break;
case T_HashJoin:
set_join_references((Join *) plan, rtable);
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
fix_expr_references(plan, (Node *) ((Join *) plan)->joinqual);
fix_expr_references(plan,
(Node *) ((HashJoin *) plan)->hashclauses);
break;
case T_Hash:
case T_Material:
case T_Sort:
case T_Unique:
case T_SetOp:
/*
* These plan types don't actually bother to evaluate their
* targetlists (because they just return their unmodified
* input tuples). The optimizer is lazy about creating really
* valid targetlists for them --- it tends to just put in a
* pointer to the child plan node's tlist. Hence, we leave
* the tlist alone. In particular, we do not want to process
* subplans in the tlist, since we will likely end up reprocessing
* subplans that also appear in lower levels of the plan tree!
*
* Since these plan types don't check quals either, we should
* not find any qual expression attached to them.
*/
Assert(plan->qual == NIL);
break;
case T_Limit:
/*
* Like the plan types above, Limit doesn't evaluate its tlist
* or quals. It does have live expressions for limit/offset,
* however.
*/
Assert(plan->qual == NIL);
fix_expr_references(plan, ((Limit *) plan)->limitOffset);
fix_expr_references(plan, ((Limit *) plan)->limitCount);
break;
case T_Agg:
case T_Group:
set_uppernode_references(plan, (Index) 0);
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
break;
case T_Result:
/*
* Result may or may not have a subplan; no need to fix up
* subplan references if it hasn't got one...
*
* XXX why does Result use a different subvarno from Agg/Group?
*/
if (plan->lefttree != NULL)
set_uppernode_references(plan, (Index) OUTER);
fix_expr_references(plan, (Node *) plan->targetlist);
fix_expr_references(plan, (Node *) plan->qual);
fix_expr_references(plan, ((Result *) plan)->resconstantqual);
break;
case T_Append:
/*
* Append, like Sort et al, doesn't actually evaluate its
* targetlist or check quals, and we haven't bothered to give it
* its own tlist copy. So, don't fix targetlist/qual. But do
* recurse into child plans.
*/
Assert(plan->qual == NIL);
foreach(l, ((Append *) plan)->appendplans)
lfirst(l) = set_plan_references((Plan *) lfirst(l), rtable);
break;
case T_BitmapAnd:
/* BitmapAnd works like Append, but has no tlist */
Assert(plan->targetlist == NIL);
Assert(plan->qual == NIL);
foreach(l, ((BitmapAnd *) plan)->bitmapplans)
lfirst(l) = set_plan_references((Plan *) lfirst(l), rtable);
break;
case T_BitmapOr:
/* BitmapOr works like Append, but has no tlist */
Assert(plan->targetlist == NIL);
Assert(plan->qual == NIL);
foreach(l, ((BitmapOr *) plan)->bitmapplans)
lfirst(l) = set_plan_references((Plan *) lfirst(l), rtable);
break;
default:
elog(ERROR, "unrecognized node type: %d",
(int) nodeTag(plan));
break;
}
/*
* Now recurse into child plans and initplans, if any
*
* NOTE: it is essential that we recurse into child plans AFTER we set
* subplan references in this plan's tlist and quals. If we did the
* reference-adjustments bottom-up, then we would fail to match this
* plan's var nodes against the already-modified nodes of the
* children. Fortunately, that consideration doesn't apply to SubPlan
* nodes; else we'd need two passes over the expression trees.
*/
plan->lefttree = set_plan_references(plan->lefttree, rtable);
plan->righttree = set_plan_references(plan->righttree, rtable);
foreach(l, plan->initPlan)
{
SubPlan *sp = (SubPlan *) lfirst(l);
Assert(IsA(sp, SubPlan));
sp->plan = set_plan_references(sp->plan, sp->rtable);
}
return plan;
}
/*
* set_subqueryscan_references
* Do set_plan_references processing on a SubqueryScan
*
* We try to strip out the SubqueryScan entirely; if we can't, we have
* to do the normal processing on it.
*/
static Plan *
set_subqueryscan_references(SubqueryScan *plan, List *rtable)
{
Plan *result;
RangeTblEntry *rte;
ListCell *l;
/* First, recursively process the subplan */
rte = rt_fetch(plan->scan.scanrelid, rtable);
Assert(rte->rtekind == RTE_SUBQUERY);
plan->subplan = set_plan_references(plan->subplan,
rte->subquery->rtable);
/*
* We have to process any initplans too; set_plan_references can't do
* it for us because of the possibility of double-processing.
*/
foreach(l, plan->scan.plan.initPlan)
{
SubPlan *sp = (SubPlan *) lfirst(l);
Assert(IsA(sp, SubPlan));
sp->plan = set_plan_references(sp->plan, sp->rtable);
}
if (trivial_subqueryscan(plan))
{
/*
* We can omit the SubqueryScan node and just pull up the subplan.
* We have to merge its rtable into the outer rtable, which means
* adjusting varnos throughout the subtree.
*/
int rtoffset = list_length(rtable);
List *sub_rtable;
sub_rtable = copyObject(rte->subquery->rtable);
range_table_walker(sub_rtable,
adjust_expr_varnos_walker,
(void *) &rtoffset,
QTW_IGNORE_RT_SUBQUERIES);
rtable = list_concat(rtable, sub_rtable);
/*
* we have to copy the subplan to make sure there are no duplicately
* linked nodes in it, else adjust_plan_varnos might increment some
* varnos twice
*/
result = copyObject(plan->subplan);
adjust_plan_varnos(result, rtoffset);
result->initPlan = list_concat(plan->scan.plan.initPlan,
result->initPlan);
}
else
{
/*
* Keep the SubqueryScan node. We have to do the processing that
* set_plan_references would otherwise have done on it. Notice
* we do not do set_uppernode_references() here, because a
* SubqueryScan will always have been created with correct
* references to its subplan's outputs to begin with.
*/
result = (Plan *) plan;
fix_expr_references(result, (Node *) result->targetlist);
fix_expr_references(result, (Node *) result->qual);
}
return result;
}
/*
* trivial_subqueryscan
* Detect whether a SubqueryScan can be deleted from the plan tree.
*
* We can delete it if it has no qual to check and the targetlist just
* regurgitates the output of the child plan.
*/
static bool
trivial_subqueryscan(SubqueryScan *plan)
{
int attrno;
ListCell *lp,
*lc;
if (plan->scan.plan.qual != NIL)
return false;
if (list_length(plan->scan.plan.targetlist) !=
list_length(plan->subplan->targetlist))
return false; /* tlists not same length */
attrno = 1;
forboth(lp, plan->scan.plan.targetlist, lc, plan->subplan->targetlist)
{
TargetEntry *ptle = (TargetEntry *) lfirst(lp);
TargetEntry *ctle = (TargetEntry *) lfirst(lc);
Var *var = (Var *) ptle->expr;
if (ptle->resjunk != ctle->resjunk)
return false; /* tlist doesn't match junk status */
if (!var || !IsA(var, Var))
return false; /* tlist item not a Var */
Assert(var->varno == plan->scan.scanrelid);
Assert(var->varlevelsup == 0);
if (var->varattno != attrno)
return false; /* out of order */
attrno++;
}
return true;
}
/*
* adjust_plan_varnos
* Offset varnos and other rangetable indexes in a plan tree by rtoffset.
*/
static void
adjust_plan_varnos(Plan *plan, int rtoffset)
{
ListCell *l;
if (plan == NULL)
return;
/*
* Plan-type-specific fixes
*/
switch (nodeTag(plan))
{
case T_SeqScan:
((SeqScan *) plan)->scanrelid += rtoffset;
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
break;
case T_IndexScan:
((IndexScan *) plan)->scan.scanrelid += rtoffset;
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
adjust_expr_varnos((Node *) ((IndexScan *) plan)->indexqual,
rtoffset);
adjust_expr_varnos((Node *) ((IndexScan *) plan)->indexqualorig,
rtoffset);
break;
case T_BitmapIndexScan:
((BitmapIndexScan *) plan)->scan.scanrelid += rtoffset;
/* no need to fix targetlist and qual */
Assert(plan->targetlist == NIL);
Assert(plan->qual == NIL);
adjust_expr_varnos((Node *) ((BitmapIndexScan *) plan)->indexqual,
rtoffset);
adjust_expr_varnos((Node *) ((BitmapIndexScan *) plan)->indexqualorig,
rtoffset);
break;
case T_BitmapHeapScan:
((BitmapHeapScan *) plan)->scan.scanrelid += rtoffset;
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
adjust_expr_varnos((Node *) ((BitmapHeapScan *) plan)->bitmapqualorig,
rtoffset);
break;
case T_TidScan:
((TidScan *) plan)->scan.scanrelid += rtoffset;
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
adjust_expr_varnos((Node *) ((TidScan *) plan)->tideval,
rtoffset);
break;
case T_SubqueryScan:
((SubqueryScan *) plan)->scan.scanrelid += rtoffset;
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
/* we should not recurse into the subquery! */
break;
case T_FunctionScan:
((FunctionScan *) plan)->scan.scanrelid += rtoffset;
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
/* rte was already fixed by set_subqueryscan_references */
break;
case T_NestLoop:
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
adjust_expr_varnos((Node *) ((Join *) plan)->joinqual, rtoffset);
break;
case T_MergeJoin:
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
adjust_expr_varnos((Node *) ((Join *) plan)->joinqual, rtoffset);
adjust_expr_varnos((Node *) ((MergeJoin *) plan)->mergeclauses,
rtoffset);
break;
case T_HashJoin:
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
adjust_expr_varnos((Node *) ((Join *) plan)->joinqual, rtoffset);
adjust_expr_varnos((Node *) ((HashJoin *) plan)->hashclauses,
rtoffset);
break;
case T_Hash:
case T_Material:
case T_Sort:
case T_Unique:
case T_SetOp:
/*
* Even though the targetlist won't be used by the executor,
* we fix it up for possible use by EXPLAIN (not to mention
* ease of debugging --- wrong varnos are very confusing).
*/
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
Assert(plan->qual == NIL);
break;
case T_Limit:
/*
* Like the plan types above, Limit doesn't evaluate its tlist
* or quals. It does have live expressions for limit/offset,
* however.
*/
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
Assert(plan->qual == NIL);
adjust_expr_varnos(((Limit *) plan)->limitOffset, rtoffset);
adjust_expr_varnos(((Limit *) plan)->limitCount, rtoffset);
break;
case T_Agg:
case T_Group:
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
break;
case T_Result:
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
adjust_expr_varnos((Node *) plan->qual, rtoffset);
adjust_expr_varnos(((Result *) plan)->resconstantqual, rtoffset);
break;
case T_Append:
adjust_expr_varnos((Node *) plan->targetlist, rtoffset);
Assert(plan->qual == NIL);
foreach(l, ((Append *) plan)->appendplans)
adjust_plan_varnos((Plan *) lfirst(l), rtoffset);
break;
case T_BitmapAnd:
/* BitmapAnd works like Append, but has no tlist */
Assert(plan->targetlist == NIL);
Assert(plan->qual == NIL);
foreach(l, ((BitmapAnd *) plan)->bitmapplans)
adjust_plan_varnos((Plan *) lfirst(l), rtoffset);
break;
case T_BitmapOr:
/* BitmapOr works like Append, but has no tlist */
Assert(plan->targetlist == NIL);
Assert(plan->qual == NIL);
foreach(l, ((BitmapOr *) plan)->bitmapplans)
adjust_plan_varnos((Plan *) lfirst(l), rtoffset);
break;
default:
elog(ERROR, "unrecognized node type: %d",
(int) nodeTag(plan));
break;
}
/*
* Now recurse into child plans.
*
* We don't need to (and in fact mustn't) recurse into subqueries,
* so no need to examine initPlan list.
*/
adjust_plan_varnos(plan->lefttree, rtoffset);
adjust_plan_varnos(plan->righttree, rtoffset);
}
/*
* adjust_expr_varnos
* Offset varnos of Vars in an expression by rtoffset.
*
* This is different from the rewriter's OffsetVarNodes in that it has to
* work on an already-planned expression tree; in particular, we should not
* disturb INNER and OUTER references. On the other hand, we don't have to
* recurse into subqueries nor deal with outer-level Vars, so it's pretty
* simple.
*/
static void
adjust_expr_varnos(Node *node, int rtoffset)
{
/* This tree walk requires no special setup, so away we go... */
adjust_expr_varnos_walker(node, &rtoffset);
}
static bool
adjust_expr_varnos_walker(Node *node, int *context)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
Var *var = (Var *) node;
Assert(var->varlevelsup == 0);
if (var->varno > 0 && var->varno != INNER && var->varno != OUTER)
var->varno += *context;
if (var->varnoold > 0)
var->varnoold += *context;
return false;
}
return expression_tree_walker(node, adjust_expr_varnos_walker,
(void *) context);
}
/*
* fix_expr_references
* Do final cleanup on expressions (targetlists or quals).
*
* This consists of looking up operator opcode info for OpExpr nodes
* and recursively performing set_plan_references on subplans.
*
* The Plan argument is currently unused, but might be needed again someday.
*/
static void
fix_expr_references(Plan *plan, Node *node)
{
/* This tree walk requires no special setup, so away we go... */
fix_expr_references_walker(node, NULL);
}
static bool
fix_expr_references_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, OpExpr))
set_opfuncid((OpExpr *) node);
else if (IsA(node, DistinctExpr))
set_opfuncid((OpExpr *) node); /* rely on struct equivalence */
else if (IsA(node, ScalarArrayOpExpr))
set_sa_opfuncid((ScalarArrayOpExpr *) node);
else if (IsA(node, NullIfExpr))
set_opfuncid((OpExpr *) node); /* rely on struct equivalence */
else if (IsA(node, SubPlan))
{
SubPlan *sp = (SubPlan *) node;
sp->plan = set_plan_references(sp->plan, sp->rtable);
}
return expression_tree_walker(node, fix_expr_references_walker, context);
}
/*
* set_join_references
* Modifies the target list and quals of a join node to reference its
* subplans, by setting the varnos to OUTER or INNER and setting attno
* values to the result domain number of either the corresponding outer
* or inner join tuple item.
*
* In the case of a nestloop with inner indexscan, we will also need to
* apply the same transformation to any outer vars appearing in the
* quals of the child indexscan. set_inner_join_references does that.
*
* 'join' is a join plan node
* 'rtable' is the associated range table
*/
static void
set_join_references(Join *join, List *rtable)
{
Plan *outer_plan = join->plan.lefttree;
Plan *inner_plan = join->plan.righttree;
indexed_tlist *outer_itlist;
indexed_tlist *inner_itlist;
outer_itlist = build_tlist_index(outer_plan->targetlist);
inner_itlist = build_tlist_index(inner_plan->targetlist);
/* All join plans have tlist, qual, and joinqual */
join->plan.targetlist = join_references(join->plan.targetlist,
rtable,
outer_itlist,
inner_itlist,
(Index) 0);
join->plan.qual = join_references(join->plan.qual,
rtable,
outer_itlist,
inner_itlist,
(Index) 0);
join->joinqual = join_references(join->joinqual,
rtable,
outer_itlist,
inner_itlist,
(Index) 0);
/* Now do join-type-specific stuff */
if (IsA(join, NestLoop))
{
/* This processing is split out to handle possible recursion */
set_inner_join_references(inner_plan,
rtable,
outer_itlist);
}
else if (IsA(join, MergeJoin))
{
MergeJoin *mj = (MergeJoin *) join;
mj->mergeclauses = join_references(mj->mergeclauses,
rtable,
outer_itlist,
inner_itlist,
(Index) 0);
}
else if (IsA(join, HashJoin))
{
HashJoin *hj = (HashJoin *) join;
hj->hashclauses = join_references(hj->hashclauses,
rtable,
outer_itlist,
inner_itlist,
(Index) 0);
}
pfree(outer_itlist);
pfree(inner_itlist);
}
/*
* set_inner_join_references
* Handle join references appearing in an inner indexscan's quals
*
* To handle bitmap-scan plan trees, we have to be able to recurse down
* to the bottom BitmapIndexScan nodes, so this is split out as a separate
* function.
*/
static void
set_inner_join_references(Plan *inner_plan,
List *rtable,
indexed_tlist *outer_itlist)
{
if (IsA(inner_plan, IndexScan))
{
/*
* An index is being used to reduce the number of tuples
* scanned in the inner relation. If there are join clauses
* being used with the index, we must update their outer-rel
* var nodes to refer to the outer side of the join.
*/
IndexScan *innerscan = (IndexScan *) inner_plan;
List *indexqualorig = innerscan->indexqualorig;
/* No work needed if indexqual refers only to its own rel... */
if (NumRelids((Node *) indexqualorig) > 1)
{
Index innerrel = innerscan->scan.scanrelid;
/* only refs to outer vars get changed in the inner qual */
innerscan->indexqualorig = join_references(indexqualorig,
rtable,
outer_itlist,
NULL,
innerrel);
innerscan->indexqual = join_references(innerscan->indexqual,
rtable,
outer_itlist,
NULL,
innerrel);
/*
* We must fix the inner qpqual too, if it has join
* clauses (this could happen if special operators are
* involved: some indexquals may get rechecked as qpquals).
*/
if (NumRelids((Node *) inner_plan->qual) > 1)
inner_plan->qual = join_references(inner_plan->qual,
rtable,
outer_itlist,
NULL,
innerrel);
}
}
else if (IsA(inner_plan, BitmapIndexScan))
{
/*
* Same, but index is being used within a bitmap plan.
*/
BitmapIndexScan *innerscan = (BitmapIndexScan *) inner_plan;
List *indexqualorig = innerscan->indexqualorig;
/* No work needed if indexqual refers only to its own rel... */
if (NumRelids((Node *) indexqualorig) > 1)
{
Index innerrel = innerscan->scan.scanrelid;
/* only refs to outer vars get changed in the inner qual */
innerscan->indexqualorig = join_references(indexqualorig,
rtable,
outer_itlist,
NULL,
innerrel);
innerscan->indexqual = join_references(innerscan->indexqual,
rtable,
outer_itlist,
NULL,
innerrel);
/* no need to fix inner qpqual */
Assert(inner_plan->qual == NIL);
}
}
else if (IsA(inner_plan, BitmapHeapScan))
{
/*
* The inner side is a bitmap scan plan. Fix the top node,
* and recurse to get the lower nodes.
*
* Note: create_bitmap_scan_plan removes clauses from bitmapqualorig
* if they are duplicated in qpqual, so must test these independently.
*/
BitmapHeapScan *innerscan = (BitmapHeapScan *) inner_plan;
Index innerrel = innerscan->scan.scanrelid;
List *bitmapqualorig = innerscan->bitmapqualorig;
/* only refs to outer vars get changed in the inner qual */
if (NumRelids((Node *) bitmapqualorig) > 1)
innerscan->bitmapqualorig = join_references(bitmapqualorig,
rtable,
outer_itlist,
NULL,
innerrel);
/*
* We must fix the inner qpqual too, if it has join
* clauses (this could happen if special operators are
* involved: some indexquals may get rechecked as qpquals).
*/
if (NumRelids((Node *) inner_plan->qual) > 1)
inner_plan->qual = join_references(inner_plan->qual,
rtable,
outer_itlist,
NULL,
innerrel);
/* Now recurse */
set_inner_join_references(inner_plan->lefttree,
rtable,
outer_itlist);
}
else if (IsA(inner_plan, BitmapAnd))
{
/* All we need do here is recurse */
BitmapAnd *innerscan = (BitmapAnd *) inner_plan;
ListCell *l;
foreach(l, innerscan->bitmapplans)
{
set_inner_join_references((Plan *) lfirst(l),
rtable,
outer_itlist);
}
}
else if (IsA(inner_plan, BitmapOr))
{
/* All we need do here is recurse */
BitmapOr *innerscan = (BitmapOr *) inner_plan;
ListCell *l;
foreach(l, innerscan->bitmapplans)
{
set_inner_join_references((Plan *) lfirst(l),
rtable,
outer_itlist);
}
}
else if (IsA(inner_plan, TidScan))
{
TidScan *innerscan = (TidScan *) inner_plan;
Index innerrel = innerscan->scan.scanrelid;
innerscan->tideval = join_references(innerscan->tideval,
rtable,
outer_itlist,
NULL,
innerrel);
}
}
/*
* set_uppernode_references
* Update the targetlist and quals of an upper-level plan node
* to refer to the tuples returned by its lefttree subplan.
*
* This is used for single-input plan types like Agg, Group, Result.
*
* In most cases, we have to match up individual Vars in the tlist and
* qual expressions with elements of the subplan's tlist (which was
* generated by flatten_tlist() from these selfsame expressions, so it
* should have all the required variables). There is an important exception,
* however: GROUP BY and ORDER BY expressions will have been pushed into the
* subplan tlist unflattened. If these values are also needed in the output
* then we want to reference the subplan tlist element rather than recomputing
* the expression.
*/
static void
set_uppernode_references(Plan *plan, Index subvarno)
{
Plan *subplan = plan->lefttree;
indexed_tlist *subplan_itlist;
List *output_targetlist;
ListCell *l;
if (subplan != NULL)
subplan_itlist = build_tlist_index(subplan->targetlist);
else
subplan_itlist = build_tlist_index(NIL);
output_targetlist = NIL;
foreach(l, plan->targetlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
Node *newexpr;
newexpr = replace_vars_with_subplan_refs((Node *) tle->expr,
subplan_itlist,
subvarno);
tle = flatCopyTargetEntry(tle);
tle->expr = (Expr *) newexpr;
output_targetlist = lappend(output_targetlist, tle);
}
plan->targetlist = output_targetlist;
plan->qual = (List *)
replace_vars_with_subplan_refs((Node *) plan->qual,
subplan_itlist,
subvarno);
pfree(subplan_itlist);
}
/*
* build_tlist_index --- build an index data structure for a child tlist
*
* In most cases, subplan tlists will be "flat" tlists with only Vars,
* so we try to optimize that case by extracting information about Vars
* in advance. Matching a parent tlist to a child is still an O(N^2)
* operation, but at least with a much smaller constant factor than plain
* tlist_member() searches.
*
* The result of this function is an indexed_tlist struct to pass to
* search_indexed_tlist_for_var() or search_indexed_tlist_for_non_var().
* When done, the indexed_tlist may be freed with a single pfree().
*/
static indexed_tlist *
build_tlist_index(List *tlist)
{
indexed_tlist *itlist;
tlist_vinfo *vinfo;
ListCell *l;
/* Create data structure with enough slots for all tlist entries */
itlist = (indexed_tlist *)
palloc(offsetof(indexed_tlist, vars) +
list_length(tlist) * sizeof(tlist_vinfo));
itlist->tlist = tlist;
itlist->has_non_vars = false;
/* Find the Vars and fill in the index array */
vinfo = itlist->vars;
foreach(l, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (tle->expr && IsA(tle->expr, Var))
{
Var *var = (Var *) tle->expr;
vinfo->varno = var->varno;
vinfo->varattno = var->varattno;
vinfo->resno = tle->resno;
vinfo++;
}
else
itlist->has_non_vars = true;
}
itlist->num_vars = (vinfo - itlist->vars);
return itlist;
}
/*
* search_indexed_tlist_for_var --- find a Var in an indexed tlist
*
* If a match is found, return a copy of the given Var with suitably
* modified varno/varattno (to wit, newvarno and the resno of the TLE entry).
* If no match, return NULL.
*/
static Var *
search_indexed_tlist_for_var(Var *var, indexed_tlist *itlist, Index newvarno)
{
Index varno = var->varno;
AttrNumber varattno = var->varattno;
tlist_vinfo *vinfo;
int i;
vinfo = itlist->vars;
i = itlist->num_vars;
while (i-- > 0)
{
if (vinfo->varno == varno && vinfo->varattno == varattno)
{
/* Found a match */
Var *newvar = (Var *) copyObject(var);
newvar->varno = newvarno;
newvar->varattno = vinfo->resno;
return newvar;
}
vinfo++;
}
return NULL; /* no match */
}
/*
* search_indexed_tlist_for_non_var --- find a non-Var in an indexed tlist
*
* If a match is found, return a Var constructed to reference the tlist item.
* If no match, return NULL.
*
* NOTE: it is a waste of time to call this if !itlist->has_non_vars
*/
static Var *
search_indexed_tlist_for_non_var(Node *node,
indexed_tlist *itlist, Index newvarno)
{
TargetEntry *tle;
tle = tlist_member(node, itlist->tlist);
if (tle)
{
/* Found a matching subplan output expression */
Var *newvar;
newvar = makeVar(newvarno,
tle->resno,
exprType((Node *) tle->expr),
exprTypmod((Node *) tle->expr),
0);
newvar->varnoold = 0; /* wasn't ever a plain Var */
newvar->varoattno = 0;
return newvar;
}
return NULL; /* no match */
}
/*
* join_references
* Creates a new set of targetlist entries or join qual clauses by
* changing the varno/varattno values of variables in the clauses
* to reference target list values from the outer and inner join
* relation target lists.
*
* This is used in two different scenarios: a normal join clause, where
* all the Vars in the clause *must* be replaced by OUTER or INNER references;
* and an indexscan being used on the inner side of a nestloop join.
* In the latter case we want to replace the outer-relation Vars by OUTER
* references, but not touch the Vars of the inner relation.
*
* For a normal join, acceptable_rel should be zero so that any failure to
* match a Var will be reported as an error. For the indexscan case,
* pass inner_itlist = NULL and acceptable_rel = the ID of the inner relation.
*
* 'clauses' is the targetlist or list of join clauses
* 'rtable' is the current range table
* 'outer_itlist' is the indexed target list of the outer join relation
* 'inner_itlist' is the indexed target list of the inner join relation,
* or NULL
* 'acceptable_rel' is either zero or the rangetable index of a relation
* whose Vars may appear in the clause without provoking an error.
*
* Returns the new expression tree. The original clause structure is
* not modified.
*/
static List *
join_references(List *clauses,
List *rtable,
indexed_tlist *outer_itlist,
indexed_tlist *inner_itlist,
Index acceptable_rel)
{
join_references_context context;
context.rtable = rtable;
context.outer_itlist = outer_itlist;
context.inner_itlist = inner_itlist;
context.acceptable_rel = acceptable_rel;
return (List *) join_references_mutator((Node *) clauses, &context);
}
static Node *
join_references_mutator(Node *node,
join_references_context *context)
{
Var *newvar;
if (node == NULL)
return NULL;
if (IsA(node, Var))
{
Var *var = (Var *) node;
/* First look for the var in the input tlists */
newvar = search_indexed_tlist_for_var(var,
context->outer_itlist,
OUTER);
if (newvar)
return (Node *) newvar;
if (context->inner_itlist)
{
newvar = search_indexed_tlist_for_var(var,
context->inner_itlist,
INNER);
if (newvar)
return (Node *) newvar;
}
/* Return the Var unmodified, if it's for acceptable_rel */
if (var->varno == context->acceptable_rel)
return (Node *) copyObject(var);
/* No referent found for Var */
elog(ERROR, "variable not found in subplan target lists");
}
/* Try matching more complex expressions too, if tlists have any */
if (context->outer_itlist->has_non_vars)
{
newvar = search_indexed_tlist_for_non_var(node,
context->outer_itlist,
OUTER);
if (newvar)
return (Node *) newvar;
}
if (context->inner_itlist && context->inner_itlist->has_non_vars)
{
newvar = search_indexed_tlist_for_non_var(node,
context->inner_itlist,
INNER);
if (newvar)
return (Node *) newvar;
}
return expression_tree_mutator(node,
join_references_mutator,
(void *) context);
}
/*
* replace_vars_with_subplan_refs
* This routine modifies an expression tree so that all Var nodes
* reference target nodes of a subplan. It is used to fix up
* target and qual expressions of non-join upper-level plan nodes.
*
* An error is raised if no matching var can be found in the subplan tlist
* --- so this routine should only be applied to nodes whose subplans'
* targetlists were generated via flatten_tlist() or some such method.
*
* If itlist->has_non_vars is true, then we try to match whole subexpressions
* against elements of the subplan tlist, so that we can avoid recomputing
* expressions that were already computed by the subplan. (This is relatively
* expensive, so we don't want to try it in the common case where the
* subplan tlist is just a flattened list of Vars.)
*
* 'node': the tree to be fixed (a target item or qual)
* 'subplan_itlist': indexed target list for subplan
* 'subvarno': varno to be assigned to all Vars
*
* The resulting tree is a copy of the original in which all Var nodes have
* varno = subvarno, varattno = resno of corresponding subplan target.
* The original tree is not modified.
*/
static Node *
replace_vars_with_subplan_refs(Node *node,
indexed_tlist *subplan_itlist,
Index subvarno)
{
replace_vars_with_subplan_refs_context context;
context.subplan_itlist = subplan_itlist;
context.subvarno = subvarno;
return replace_vars_with_subplan_refs_mutator(node, &context);
}
static Node *
replace_vars_with_subplan_refs_mutator(Node *node,
replace_vars_with_subplan_refs_context *context)
{
Var *newvar;
if (node == NULL)
return NULL;
if (IsA(node, Var))
{
Var *var = (Var *) node;
newvar = search_indexed_tlist_for_var(var,
context->subplan_itlist,
context->subvarno);
if (!newvar)
elog(ERROR, "variable not found in subplan target list");
return (Node *) newvar;
}
/* Try matching more complex expressions too, if tlist has any */
if (context->subplan_itlist->has_non_vars)
{
newvar = search_indexed_tlist_for_non_var(node,
context->subplan_itlist,
context->subvarno);
if (newvar)
return (Node *) newvar;
}
return expression_tree_mutator(node,
replace_vars_with_subplan_refs_mutator,
(void *) context);
}
/*****************************************************************************
* OPERATOR REGPROC LOOKUP
*****************************************************************************/
/*
* fix_opfuncids
* Calculate opfuncid field from opno for each OpExpr node in given tree.
* The given tree can be anything expression_tree_walker handles.
*
* The argument is modified in-place. (This is OK since we'd want the
* same change for any node, even if it gets visited more than once due to
* shared structure.)
*/
void
fix_opfuncids(Node *node)
{
/* This tree walk requires no special setup, so away we go... */
fix_opfuncids_walker(node, NULL);
}
static bool
fix_opfuncids_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, OpExpr))
set_opfuncid((OpExpr *) node);
else if (IsA(node, DistinctExpr))
set_opfuncid((OpExpr *) node); /* rely on struct equivalence */
else if (IsA(node, ScalarArrayOpExpr))
set_sa_opfuncid((ScalarArrayOpExpr *) node);
else if (IsA(node, NullIfExpr))
set_opfuncid((OpExpr *) node); /* rely on struct equivalence */
return expression_tree_walker(node, fix_opfuncids_walker, context);
}
/*
* set_opfuncid
* Set the opfuncid (procedure OID) in an OpExpr node,
* if it hasn't been set already.
*
* Because of struct equivalence, this can also be used for
* DistinctExpr and NullIfExpr nodes.
*/
void
set_opfuncid(OpExpr *opexpr)
{
if (opexpr->opfuncid == InvalidOid)
opexpr->opfuncid = get_opcode(opexpr->opno);
}
/*
* set_sa_opfuncid
* As above, for ScalarArrayOpExpr nodes.
*/
static void
set_sa_opfuncid(ScalarArrayOpExpr *opexpr)
{
if (opexpr->opfuncid == InvalidOid)
opexpr->opfuncid = get_opcode(opexpr->opno);
}