Clean up messy clause-selectivity code in clausesel.c; repair bug

identified by Hiroshi (incorrect cost attributed to OR clauses
after multiple passes through set_rest_selec()).  I think the code
was trying to allow selectivities of OR subclauses to be passed in
from outside, but noplace was actually passing any useful data, and
set_rest_selec() was passing wrong data.

Restructure representation of "indexqual" in IndexPath nodes so that
it is the same as for indxqual in completed IndexScan nodes: namely,
a toplevel list with an entry for each pass of the index scan, having
sublists that are implicitly-ANDed index qual conditions for that pass.
You don't want to know what the old representation was :-(

Improve documentation of OR-clause indexscan functions.

Remove useless 'notclause' field from RestrictInfo nodes.  (This might
force an initdb for anyone who has stored rules containing RestrictInfos,
but I do not think that RestrictInfo ever appears in completed plans.)

src/backend/nodes/copyfuncs.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.86 1999/07/17 20:17:05 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.87 1999/07/24 23:21:06 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1317,7 +1317,6 @@ _copyRestrictInfo(RestrictInfo *from)
 	Node_Copy(from, newnode, clause);
 
 	newnode->selectivity = from->selectivity;
-	newnode->notclause = from->notclause;
 
 	Node_Copy(from, newnode, indexids);
 	Node_Copy(from, newnode, mergejoinorder);

src/backend/nodes/equalfuncs.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.43 1999/07/17 20:17:05 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.44 1999/07/24 23:21:06 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -305,8 +305,6 @@ _equalRestrictInfo(RestrictInfo *a, RestrictInfo *b)
 		return false;
 	if (a->selectivity != b->selectivity)
 		return false;
-	if (a->notclause != b->notclause)
-		return false;
 #ifdef EqualMergeOrderExists
 	if (!EqualMergeOrder(a->mergejoinorder, b->mergejoinorder))
 		return false;

src/backend/nodes/outfuncs.c

@@ -5,7 +5,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- *	$Id: outfuncs.c,v 1.90 1999/07/18 19:02:49 tgl Exp $
+ *	$Id: outfuncs.c,v 1.91 1999/07/24 23:21:07 tgl Exp $
  *
  * NOTES
  *	  Every (plan) node in POSTGRES has an associated "out" routine which
@@ -1110,9 +1110,8 @@ _outRestrictInfo(StringInfo str, RestrictInfo *node)
 	_outNode(str, node->clause);
 
 	appendStringInfo(str,
-					 " :selectivity %f :notclause %s :indexids ",
-					 node->selectivity,
-					 node->notclause ? "true" : "false");
+					 " :selectivity %f :indexids ",
+					 node->selectivity);
 	_outNode(str, node->indexids);
 
 	appendStringInfo(str, " :mergejoinorder ");

src/backend/nodes/readfuncs.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.69 1999/07/17 20:17:08 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.70 1999/07/24 23:21:08 tgl Exp $
  *
  * NOTES
  *	  Most of the read functions for plan nodes are tested. (In fact, they
@@ -1856,14 +1856,6 @@ _readRestrictInfo()
 
 	local_node->selectivity = atof(token);
 
-	token = lsptok(NULL, &length);		/* get :notclause */
-	token = lsptok(NULL, &length);		/* now read it */
-
-	if (!strncmp(token, "true", 4))
-		local_node->notclause = true;
-	else
-		local_node->notclause = false;
-
 	token = lsptok(NULL, &length);		/* get :indexids */
 	local_node->indexids = nodeRead(true);		/* now read it */
 

src/backend/optimizer/path/allpaths.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.50 1999/07/17 20:17:11 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.51 1999/07/24 23:21:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -86,8 +86,8 @@ make_one_rel(Query *root, List *rels)
  * set_base_rel_pathlist
  *	  Finds all paths available for scanning each relation entry in
  *	  'rels'.  Sequential scan and any available indices are considered
- *	  if possible(indices are not considered for lower nesting levels).
- *	  All unique paths are attached to the relation's 'pathlist' field.
+ *	  if possible (indices are not considered for lower nesting levels).
+ *	  All useful paths are attached to the relation's 'pathlist' field.
  *
  *	  MODIFIES: rels
  */
@@ -98,21 +98,32 @@ set_base_rel_pathlist(Query *root, List *rels)
 
 	foreach(temp, rels)
 	{
+		RelOptInfo *rel = (RelOptInfo *) lfirst(temp);
+		List	   *indices = find_relation_indices(root, rel);
 		List	   *sequential_scan_list;
 		List	   *rel_index_scan_list;
 		List	   *or_index_scan_list;
-		RelOptInfo *rel = (RelOptInfo *) lfirst(temp);
 
 		sequential_scan_list = lcons(create_seqscan_path(rel), NIL);
 
 		rel_index_scan_list = create_index_paths(root,
 												 rel,
-										find_relation_indices(root, rel),
+												 indices,
 												 rel->restrictinfo,
 												 rel->joininfo);
 
-		or_index_scan_list = create_or_index_paths(root, rel, rel->restrictinfo);
+		/* Note: create_or_index_paths depends on create_index_paths
+		 * to have marked OR restriction clauses with relevant indices;
+		 * this is why it doesn't need to be given the full list of indices.
+		 */
 
+		or_index_scan_list = create_or_index_paths(root, rel,
+												   rel->restrictinfo);
+
+		/* add_pathlist will discard any paths that are dominated by
+		 * another available path, keeping only those paths that are
+		 * superior along at least one dimension of cost or sortedness.
+		 */
 		rel->pathlist = add_pathlist(rel,
 									 sequential_scan_list,
 									 nconc(rel_index_scan_list,
@@ -128,7 +139,6 @@ set_base_rel_pathlist(Query *root, List *rels)
 		rel->size = compute_rel_size(rel);
 		rel->width = compute_rel_width(rel);
 	}
-	return;
 }
 
 /*

src/backend/optimizer/path/indxpath.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.62 1999/07/23 03:34:49 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.63 1999/07/24 23:21:09 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -109,12 +109,25 @@ create_index_paths(Query *root,
 				continue;
 
 		/*
-		 * 1. Try matching the index against subclauses of an 'or' clause.
-		 * The fields of the restrictinfo nodes are marked with lists of
-		 * the matching indices.  No paths are actually created.  We
-		 * currently only look to match the first key.	We don't find
-		 * multi-key index cases where an AND matches the first key, and
-		 * the OR matches the second key.
+		 * 1. Try matching the index against subclauses of restriction 'or'
+		 * clauses (ie, 'or' clauses that reference only this relation).
+		 * The restrictinfo nodes for the 'or' clauses are marked with lists
+		 * of the matching indices.  No paths are actually created now;
+		 * that will be done in orindxpath.c after all indexes for the rel
+		 * have been examined.  (We need to do it that way because we can
+		 * potentially use a different index for each subclause of an 'or',
+		 * so we can't build a path for an 'or' clause until all indexes have
+		 * been matched against it.)
+		 *
+		 * We currently only look to match the first key of each index against
+		 * 'or' subclauses.  There are cases where a later key of a multi-key
+		 * index could be used (if other top-level clauses match earlier keys
+		 * of the index), but our poor brains are hurting already...
+		 *
+		 * We don't even think about special handling of 'or' clauses that
+		 * involve more than one relation, since they can't be processed by
+		 * a single indexscan path anyway.  Currently, cnfify() is certain
+		 * to have restructured any such toplevel 'or' clauses anyway.
 		 */
 		match_index_orclauses(rel,
 							  index,
@@ -123,7 +136,7 @@ create_index_paths(Query *root,
 							  restrictinfo_list);
 
 		/*
-		 * 2. If the keys of this index match any of the available
+		 * 2. If the keys of this index match any of the available non-'or'
 		 * restriction clauses, then create a path using those clauses
 		 * as indexquals.
 		 */
@@ -179,11 +192,14 @@ create_index_paths(Query *root,
 /*
  * match_index_orclauses
  *	  Attempt to match an index against subclauses within 'or' clauses.
- *	  If the index does match, then the clause is marked with information
- *	  about the index.
+ *	  Each subclause that does match is marked with the index's node.
  *
- *	  Essentially, this adds 'index' to the list of indices in the
- *	  RestrictInfo field of each of the clauses which it matches.
+ *	  Essentially, this adds 'index' to the list of subclause indices in
+ *	  the RestrictInfo field of each of the 'or' clauses where it matches.
+ *	  NOTE: we can use storage in the RestrictInfo for this purpose because
+ *	  this processing is only done on single-relation restriction clauses.
+ *	  Therefore, we will never have indexes for more than one relation
+ *	  mentioned in the same RestrictInfo node's list.
  *
  * 'rel' is the node of the relation on which the index is defined.
  * 'index' is the index node.
@@ -204,12 +220,11 @@ match_index_orclauses(RelOptInfo *rel,
 	{
 		RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(i);
 
-		if (valid_or_clause(restrictinfo))
+		if (restriction_is_or_clause(restrictinfo))
 		{
 			/*
-			 * Mark the 'or' clause with a list of indices which match
-			 * each of its subclauses.	We add entries to the existing
-			 * list, if any.
+			 * Add this index to the subclause index list for each
+			 * subclause that it matches.
 			 */
 			restrictinfo->indexids =
 				match_index_orclause(rel, index,
@@ -253,7 +268,9 @@ match_index_orclause(RelOptInfo *rel,
 	List	   *index_list;
 	List	   *clist;
 
-	/* first time through, we create empty list of same length as OR clause */
+	/* first time through, we create list of same length as OR clause,
+	 * containing an empty sublist for each subclause.
+	 */
 	if (!other_matching_indices)
 	{
 		matching_indices = NIL;
@@ -1186,9 +1203,13 @@ index_innerjoin(Query *root, RelOptInfo *rel, List *clausegroup_list,
 		pathnode->path.pathorder->ord.sortop = index->ordering;
 		pathnode->path.pathkeys = NIL;
 
+		/* Note that we are making a pathnode for a single-scan indexscan;
+		 * therefore, both indexid and indexqual should be single-element
+		 * lists.
+		 */
 		pathnode->indexid = index->relids;
 		pathnode->indexkeys = index->indexkeys;
-		pathnode->indexqual = clausegroup;
+		pathnode->indexqual = lcons(get_actual_clauses(clausegroup), NIL);
 
 		pathnode->path.joinid = ((RestrictInfo *) lfirst(clausegroup))->restrictinfojoinid;
 

src/backend/optimizer/plan/createplan.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.62 1999/07/17 20:17:13 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.63 1999/07/24 23:21:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -301,54 +301,30 @@ create_seqscan_node(Path *best_path, List *tlist, List *scan_clauses)
  * create_indexscan_node
  *	  Returns a indexscan node for the base relation scanned by 'best_path'
  *	  with restriction clauses 'scan_clauses' and targetlist 'tlist'.
+ *
+ * If an 'or' clause is to be used with this index, the indxqual field
+ * will contain a list of the 'or' clause arguments, e.g., the
+ * clause(OR a b c) will generate: ((a) (b) (c)).  Otherwise, the
+ * indxqual will simply contain one conjunctive qualification: ((a)).
  */
 static IndexScan *
 create_indexscan_node(IndexPath *best_path,
 					  List *tlist,
 					  List *scan_clauses)
 {
-
-	/*
-	 * Extract the(first if conjunct, only if disjunct) clause from the
-	 * restrictinfo list.
-	 */
-	Expr	   *index_clause = (Expr *) NULL;
-	List	   *indxqual = NIL;
-	List	   *qpqual = NIL;
-	List	   *fixed_indxqual = NIL;
+	List	   *indxqual = best_path->indexqual;
+	List	   *qpqual;
+	List	   *fixed_indxqual;
 	List	   *ixid;
-	IndexScan  *scan_node = (IndexScan *) NULL;
-	bool		lossy = FALSE;
-	HeapTuple	indexTuple;
-	Form_pg_index index;
-
-	/*
-	 * If an 'or' clause is to be used with this index, the indxqual field
-	 * will contain a list of the 'or' clause arguments, e.g., the
-	 * clause(OR a b c) will generate: ((a) (b) (c)).  Otherwise, the
-	 * indxqual will simply contain one conjunctive qualification: ((a)).
-	 */
-	if (best_path->indexqual != NULL)
-		/* added call to fix_opids, JMH 6/23/92 */
-		index_clause = (Expr *)
-			lfirst(fix_opids(get_actual_clauses(best_path->indexqual)));
-
-	if (or_clause((Node *) index_clause))
-	{
-		List	   *temp = NIL;
-
-		foreach(temp, index_clause->args)
-			indxqual = lappend(indxqual, lcons(lfirst(temp), NIL));
-	}
-	else
-	{
-		indxqual = lcons(get_actual_clauses(best_path->indexqual),
-						 NIL);
-	}
+	IndexScan  *scan_node;
+	bool		lossy = false;
 
 	/* check and see if any indices are lossy */
 	foreach(ixid, best_path->indexid)
 	{
+		HeapTuple	indexTuple;
+		Form_pg_index index;
+
 		indexTuple = SearchSysCacheTuple(INDEXRELID,
 										 ObjectIdGetDatum(lfirsti(ixid)),
 										 0, 0, 0);
@@ -356,34 +332,70 @@ create_indexscan_node(IndexPath *best_path,
 			elog(ERROR, "create_plan: index %u not found", lfirsti(ixid));
 		index = (Form_pg_index) GETSTRUCT(indexTuple);
 		if (index->indislossy)
-			lossy = TRUE;
+		{
+			lossy = true;
+			break;
+		}
 	}
 
-
 	/*
-	 * The qpqual field contains all restrictions not automatically
+	 * The qpqual list must contain all restrictions not automatically
 	 * handled by the index.  Note that for non-lossy indices, the
 	 * predicates in the indxqual are handled by the index, while for
 	 * lossy indices the indxqual predicates need to be double-checked
 	 * after the index fetches the best-guess tuples.
+	 *
+	 * There should not be any clauses in scan_clauses that duplicate
+	 * expressions checked by the index, but just in case, we will
+	 * get rid of them via set_difference.
 	 */
-	if (or_clause((Node *) index_clause))
+	if (length(indxqual) > 1)
 	{
+		/*
+		 * Build an expression representation of the indexqual, expanding
+		 * the implicit OR and AND semantics of the first- and second-level
+		 * lists.  XXX Is it really necessary to do a deep copy here?
+		 */
+		List	   *orclauses = NIL;
+		List	   *orclause;
+		Expr	   *indxqual_expr;
+
+		foreach(orclause, indxqual)
+		{
+			orclauses = lappend(orclauses,
+								make_ands_explicit((List *) copyObject(lfirst(orclause))));
+		}
+		indxqual_expr = make_orclause(orclauses);
+
+		/* this set_difference is almost certainly a waste of time... */
 		qpqual = set_difference(scan_clauses,
-								lcons(index_clause, NIL));
+								lcons(indxqual_expr, NIL));
 
 		if (lossy)
-			qpqual = lappend(qpqual, (List *) copyObject(index_clause));
+			qpqual = lappend(qpqual, indxqual_expr);
 	}
-	else
+	else if (indxqual != NIL)
 	{
+		/* Here, we can simply treat the first sublist as an independent
+		 * set of qual expressions, since there is no top-level OR behavior.
+		 */
 		qpqual = set_difference(scan_clauses, lfirst(indxqual));
 		if (lossy)
-			qpqual = nconc(qpqual,
-						   (List *) copyObject(lfirst(indxqual)));
+			qpqual = nconc(qpqual, (List *) copyObject(lfirst(indxqual)));
 	}
+	else
+		qpqual = NIL;
+
+	/*
+	 * Fix opids in the completed indxqual.  We don't want to do this sooner
+	 * since it would screw up the set_difference calcs above.  Really,
+	 * this ought to only happen at final exit from the planner...
+	 */
+	indxqual = fix_opids(indxqual);
 
-	fixed_indxqual = (List *) fix_indxqual_references((Node *) indxqual, (Path *) best_path);
+	/* The executor needs a copy with index attrs substituted for table ones */
+	fixed_indxqual = (List *) fix_indxqual_references((Node *) indxqual,
+													  (Path *) best_path);
 
 	scan_node = make_indexscan(tlist,
 							   qpqual,

src/backend/optimizer/plan/initsplan.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.34 1999/07/16 04:59:19 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.35 1999/07/24 23:21:12 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -25,12 +25,11 @@
 #include "optimizer/var.h"
 #include "utils/lsyscache.h"
 
-extern int	Quiet;
 
-static void add_restrict_and_join_to_rel(Query *root, List *clause);
+static void add_restrict_and_join_to_rel(Query *root, Node *clause);
 static void add_join_info_to_rels(Query *root, RestrictInfo *restrictinfo,
 					  Relids join_relids);
-static void add_vars_to_targetlist(Query *root, List *vars, Relids join_relids);
+static void add_vars_to_targetlist(Query *root, List *vars);
 
 static MergeOrder *mergejoinop(Expr *clause);
 static Oid	hashjoinop(Expr *clause);
@@ -129,7 +128,7 @@ add_missing_vars_to_tlist(Query *root, List *tlist)
  *	  relations appearing within clauses.  Creates new relation entries if
  *	  necessary, adding them to *query_relation_list*.
  *
- *	  Returns nothing of interest.
+ * 'clauses': the list of clauses in the cnfify'd query qualification.
  */
 void
 add_restrict_and_join_to_rels(Query *root, List *clauses)
@@ -137,95 +136,71 @@ add_restrict_and_join_to_rels(Query *root, List *clauses)
 	List	   *clause;
 
 	foreach(clause, clauses)
-		add_restrict_and_join_to_rel(root, lfirst(clause));
-	return;
+		add_restrict_and_join_to_rel(root, (Node*) lfirst(clause));
 }
 
 /*
  * add_restrict_and_join_to_rel-
  *	  Add clause information to either the 'RestrictInfo' or 'JoinInfo' field
- *	  of a relation entry(depending on whether or not the clause is a join)
+ *	  of a relation entry (depending on whether or not the clause is a join)
  *	  by creating a new RestrictInfo node and setting appropriate fields
  *	  within the nodes.
- *
- *	  Returns nothing of interest.
  */
 static void
-add_restrict_and_join_to_rel(Query *root, List *clause)
+add_restrict_and_join_to_rel(Query *root, Node *clause)
 {
+	RestrictInfo *restrictinfo = makeNode(RestrictInfo);
 	Relids		relids;
 	List	   *vars;
-	RestrictInfo *restrictinfo = makeNode(RestrictInfo);
-
-	/*
-	 * Retrieve all relids and vars contained within the clause.
-	 */
-	clause_get_relids_vars((Node *) clause, &relids, &vars);
 
 	restrictinfo->clause = (Expr *) clause;
-	restrictinfo->notclause = contains_not((Node *) clause);
-	restrictinfo->selectivity = 0;
 	restrictinfo->indexids = NIL;
 	restrictinfo->mergejoinorder = (MergeOrder *) NULL;
 	restrictinfo->hashjoinoperator = (Oid) 0;
 
+	/*
+	 * The selectivity of the clause must be computed regardless of
+	 * whether it's a restriction or a join clause
+	 */
+	restrictinfo->selectivity = compute_clause_selec(root, clause);
+
+	/*
+	 * Retrieve all relids and vars contained within the clause.
+	 */
+	clause_get_relids_vars(clause, &relids, &vars);
+
 	if (length(relids) == 1)
 	{
-
 		/*
 		 * There is only one relation participating in 'clause', so
-		 * 'clause' must be a restriction clause.
+		 * 'clause' must be a restriction clause for that relation.
 		 */
 		RelOptInfo *rel = get_base_rel(root, lfirsti(relids));
 
-		/*
-		 * The selectivity of the clause must be computed regardless of
-		 * whether it's a restriction or a join clause
-		 */
-		if (is_funcclause((Node *) clause))
-
-			/*
-			 * XXX If we have a func clause set selectivity to 1/3, really
-			 * need a true selectivity function.
-			 */
-			restrictinfo->selectivity = (Cost) 0.3333333;
-		else
-			restrictinfo->selectivity = compute_clause_selec(root, (Node *) clause, NIL);
-
 		rel->restrictinfo = lcons(restrictinfo, rel->restrictinfo);
 	}
 	else
 	{
-
 		/*
 		 * 'clause' is a join clause, since there is more than one atom in
-		 * the relid list.
+		 * the relid list.  Add it to the join lists of all the relevant
+		 * relations.  (If, perchance, 'clause' contains NO vars, then
+		 * nothing will happen...)
 		 */
-		if (is_funcclause((Node *) clause))
-
-			/*
-			 * XXX If we have a func clause set selectivity to 1/3, really
-			 * need a true selectivity function.
-			 */
-			restrictinfo->selectivity = (Cost) 0.3333333;
-		else
-			restrictinfo->selectivity = compute_clause_selec(root, (Node *) clause, NIL);
-
 		add_join_info_to_rels(root, restrictinfo, relids);
-		/* we are going to be doing a join, so add var to targetlist */
-		add_vars_to_targetlist(root, vars, relids);
+		/* we are going to be doing a join, so add vars to targetlists */
+		add_vars_to_targetlist(root, vars);
 	}
 }
 
 /*
  * add_join_info_to_rels
  *	  For every relation participating in a join clause, add 'restrictinfo' to
- *	  the appropriate joininfo node(creating a new one and adding it to the
+ *	  the appropriate joininfo node (creating a new one and adding it to the
  *	  appropriate rel node if necessary).
  *
  * 'restrictinfo' describes the join clause
  * 'join_relids' is the list of relations participating in the join clause
- *
  */
 static void
 add_join_info_to_rels(Query *root, RestrictInfo *restrictinfo,
@@ -233,7 +208,7 @@ add_join_info_to_rels(Query *root, RestrictInfo *restrictinfo,
 {
 	List	   *join_relid;
 
-	/* For every relid, find the rel, and add the proper join entries */
+	/* For every relid, find the joininfo, and add the proper join entries */
 	foreach(join_relid, join_relids)
 	{
 		JoinInfo   *joininfo;
@@ -247,43 +222,39 @@ add_join_info_to_rels(Query *root, RestrictInfo *restrictinfo,
 				unjoined_relids = lappendi(unjoined_relids, lfirsti(rel));
 		}
 
+		/*
+		 * Find or make the joininfo node for this combination of rels
+		 */
 		joininfo = find_joininfo_node(get_base_rel(root, lfirsti(join_relid)),
 									  unjoined_relids);
+
+		/*
+		 * And add the restrictinfo node to it.  NOTE that each joininfo
+		 * gets its own copy of the restrictinfo node!  (Is this really
+		 * necessary?  Possibly ... later parts of the optimizer destructively
+		 * modify restrict/join clauses...)
+		 */
 		joininfo->jinfo_restrictinfo = lcons(copyObject((void *) restrictinfo),
-										   joininfo->jinfo_restrictinfo);
+											 joininfo->jinfo_restrictinfo);
 	}
 }
 
 /*
  * add_vars_to_targetlist
- *	  For each variable appearing in a clause,
- *	  (1) If a targetlist entry for the variable is not already present in
- *		  the appropriate relation's target list, add one.
- *	  (2) If a targetlist entry is already present, but the var is part of a
- *		  join clause, add the relids of the join relations to the JoinList
- *		  entry of the targetlist entry.
- *
- *	  'vars' is the list of var nodes
- *	  'join_relids' is the list of relids appearing in the join clause
- *		(if this is a join clause)
- *
- *	  Returns nothing.
+ *	  For each variable appearing in a clause, add it to the relation's
+ *	  targetlist if not already present.
  */
 static void
-add_vars_to_targetlist(Query *root, List *vars, Relids join_relids)
+add_vars_to_targetlist(Query *root, List *vars)
 {
-	Var		   *var;
-	List	   *temp = NIL;
-	RelOptInfo *rel = (RelOptInfo *) NULL;
-	TargetEntry *tlistentry;
+	List	   *temp;
 
 	foreach(temp, vars)
 	{
-		var = (Var *) lfirst(temp);
-		rel = get_base_rel(root, var->varno);
-		tlistentry = tlistentry_member(var, rel->targetlist);
-		if (tlistentry == NULL)
-			/* add a new entry */
+		Var		   *var = (Var *) lfirst(temp);
+		RelOptInfo *rel = get_base_rel(root, var->varno);
+
+		if (tlistentry_member(var, rel->targetlist) == NULL)
 			add_var_to_tlist(rel, var);
 	}
 }

src/backend/optimizer/util/clauses.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.40 1999/07/16 04:59:23 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.41 1999/07/24 23:21:13 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -290,6 +290,21 @@ make_andclause(List *andclauses)
 	return expr;
 }
 
+/*
+ * Sometimes (such as in the result of cnfify), we use lists of expression
+ * nodes with implicit AND semantics.  This function converts back to an
+ * explicit-AND representation.
+ */
+Expr *
+make_ands_explicit(List *andclauses)
+{
+	if (andclauses == NIL)
+		return NULL;
+	else if (length(andclauses) == 1)
+		return (Expr *) lfirst(andclauses);
+	else
+		return make_andclause(andclauses);
+}
 
 /*****************************************************************************
  *		CASE clause functions
@@ -410,38 +425,6 @@ NumRelids(Node *clause)
 	return length(var_list);
 }
 
-/*
- * contains_not
- *
- * Returns t iff the clause is a 'not' clause or if any of the
- * subclauses within an 'or' clause contain 'not's.
- *
- * NOTE that only the top-level AND/OR structure is searched for NOTs;
- * we are not interested in buried substructure.
- */
-bool
-contains_not(Node *clause)
-{
-	if (single_node(clause))
-		return false;
-
-	if (not_clause(clause))
-		return true;
-
-	if (or_clause(clause) || and_clause(clause))
-	{
-		List	   *a;
-
-		foreach(a, ((Expr *) clause)->args)
-		{
-			if (contains_not(lfirst(a)))
-				return true;
-		}
-	}
-
-	return false;
-}
-
 /*
  * is_joinable
  *

src/backend/optimizer/util/pathnode.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.46 1999/07/16 04:59:25 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.47 1999/07/24 23:21:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -426,7 +426,8 @@ create_index_path(Query *root,
 		/* each clause gets an equal selectivity */
 		clausesel = pow(selec, 1.0 / (double) length(restriction_clauses));
 
-		pathnode->indexqual = restriction_clauses;
+		pathnode->indexqual = lcons(get_actual_clauses(restriction_clauses),
+									NIL);
 		pathnode->path.path_cost = cost_index(lfirsti(index->relids),
 											  (int) npages,
 											  selec,

src/backend/optimizer/util/restrictinfo.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/restrictinfo.c,v 1.6 1999/07/16 04:59:27 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/restrictinfo.c,v 1.7 1999/07/24 23:21:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -20,17 +20,15 @@
 #include "optimizer/restrictinfo.h"
 
 /*
- * valid_or_clause
+ * restriction_is_or_clause
  *
- * Returns t iff the restrictinfo node contains a 'normal' 'or' clause.
+ * Returns t iff the restrictinfo node contains an 'or' clause.
  *
  */
 bool
-valid_or_clause(RestrictInfo *restrictinfo)
+restriction_is_or_clause(RestrictInfo *restrictinfo)
 {
 	if (restrictinfo != NULL &&
-		!single_node((Node *) restrictinfo->clause) &&
-		!restrictinfo->notclause &&
 		or_clause((Node *) restrictinfo->clause))
 		return true;
 	else

src/include/nodes/relation.h

@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: relation.h,v 1.34 1999/07/15 23:03:56 momjian Exp $
+ * $Id: relation.h,v 1.35 1999/07/24 23:21:04 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -151,6 +151,23 @@ typedef struct Path
 	List	   *loc_restrictinfo;
 } Path;
 
+/*----------
+ * IndexPath represents an index scan.  Although an indexscan can only read
+ * a single relation, it can scan it more than once, potentially using a
+ * different index during each scan.  The result is the union (OR) of all the
+ * tuples matched during any scan.  (The executor is smart enough not to return
+ * the same tuple more than once, even if it is matched in multiple scans.)
+ * 'indexid' is a list of index relation OIDs, one per scan to be performed.
+ * 'indexqual' is a list of index qualifications, also one per scan.
+ * Each entry in 'indexqual' is a sublist of qualification expressions with
+ * implicit AND semantics across the sublist items.  Each one of the sublist
+ * items must be an operator expression of the form (var op something) or
+ * (something op var), where the var is a field the associated index keys on
+ * and the op is a member of the operator class of the index.
+ * NOTE that the semantics of the top-level list in 'indexqual' is OR
+ * combination, while the sublists are implicitly AND combinations!
+ *----------
+ */
 typedef struct IndexPath
 {
 	Path		path;
@@ -205,16 +222,20 @@ typedef struct JoinKey
 } JoinKey;
 
 /*
- * clause info
+ * Restriction clause info.
+ * We create one of these for each AND sub-clause of a restriction condition
+ * (WHERE clause).  Since the restriction clauses are logically ANDed, we
+ * can use any one of them or any subset of them to filter out tuples,
+ * without having to evaluate the rest.  The RestrictInfo node itself stores
+ * data used by the optimizer while choosing the best query plan.
  */
 
 typedef struct RestrictInfo
 {
 	NodeTag		type;
-	Expr	   *clause;			/* should be an OP clause */
-	Cost		selectivity;
-	bool		notclause;
-	List	   *indexids;
+	Expr	   *clause;			/* the represented subclause of WHERE cond */
+	Cost		selectivity;	/* estimated selectivity */
+	List	   *indexids;		/* subclause index IDs if clause is an OR */
 
 	/* mergejoin only */
 	MergeOrder *mergejoinorder;

src/include/optimizer/clauses.h

@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: clauses.h,v 1.21 1999/07/15 23:03:57 momjian Exp $
+ * $Id: clauses.h,v 1.22 1999/07/24 23:21:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -34,13 +34,13 @@ extern Expr *get_notclausearg(Expr *notclause);
 
 extern bool and_clause(Node *clause);
 extern Expr *make_andclause(List *andclauses);
+extern Expr *make_ands_explicit(List *andclauses);
 
 extern bool case_clause(Node *clause);
 
 extern List *pull_constant_clauses(List *quals, List **constantQual);
 extern void clause_get_relids_vars(Node *clause, Relids *relids, List **vars);
 extern int	NumRelids(Node *clause);
-extern bool contains_not(Node *clause);
 extern bool is_joinable(Node *clause);
 extern bool qual_clause_p(Node *clause);
 extern void fix_opid(Node *clause);

src/include/optimizer/cost.h

@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: cost.h,v 1.21 1999/07/15 15:21:20 momjian Exp $
+ * $Id: cost.h,v 1.22 1999/07/24 23:21:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -59,7 +59,6 @@ extern void set_clause_selectivities(List *restrictinfo_list, Cost new_selectivi
 extern Cost product_selec(List *restrictinfo_list);
 extern void set_rest_relselec(Query *root, List *rel_list);
 extern void set_rest_selec(Query *root, List *restrictinfo_list);
-extern Cost compute_clause_selec(Query *root,
-					 Node *clause, List *or_selectivities);
+extern Cost compute_clause_selec(Query *root, Node *clause);
 
 #endif	 /* COST_H */

src/include/optimizer/restrictinfo.h

@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: restrictinfo.h,v 1.5 1999/07/15 15:21:23 momjian Exp $
+ * $Id: restrictinfo.h,v 1.6 1999/07/24 23:21:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -15,7 +15,7 @@
 
 #include "nodes/relation.h"
 
-extern bool valid_or_clause(RestrictInfo *restrictinfo);
+extern bool restriction_is_or_clause(RestrictInfo *restrictinfo);
 extern List *get_actual_clauses(List *restrictinfo_list);
 extern void get_relattvals(List *restrictinfo_list, List **attnos,
 			   List **values, List **flags);