Adding upstream version 15.5.upstream/15.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3817 insertions, 0 deletions

diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
new file mode 100644
index 0000000..3800f0c
--- /dev/null
+++ b/src/backend/optimizer/path/indxpath.c
@@ -0,0 +1,3817 @@
+/*-------------------------------------------------------------------------
+ *
+ * indxpath.c
+ *	  Routines to determine which indexes are usable for scanning a
+ *	  given relation, and create Paths accordingly.
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/optimizer/path/indxpath.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <math.h>
+
+#include "access/stratnum.h"
+#include "access/sysattr.h"
+#include "catalog/pg_am.h"
+#include "catalog/pg_operator.h"
+#include "catalog/pg_opfamily.h"
+#include "catalog/pg_type.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "nodes/supportnodes.h"
+#include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
+#include "optimizer/pathnode.h"
+#include "optimizer/paths.h"
+#include "optimizer/prep.h"
+#include "optimizer/restrictinfo.h"
+#include "utils/lsyscache.h"
+#include "utils/selfuncs.h"
+
+
+/* XXX see PartCollMatchesExprColl */
+#define IndexCollMatchesExprColl(idxcollation, exprcollation) \
+	((idxcollation) == InvalidOid || (idxcollation) == (exprcollation))
+
+/* Whether we are looking for plain indexscan, bitmap scan, or either */
+typedef enum
+{
+	ST_INDEXSCAN,				/* must support amgettuple */
+	ST_BITMAPSCAN,				/* must support amgetbitmap */
+	ST_ANYSCAN					/* either is okay */
+} ScanTypeControl;
+
+/* Data structure for collecting qual clauses that match an index */
+typedef struct
+{
+	bool		nonempty;		/* True if lists are not all empty */
+	/* Lists of IndexClause nodes, one list per index column */
+	List	   *indexclauses[INDEX_MAX_KEYS];
+} IndexClauseSet;
+
+/* Per-path data used within choose_bitmap_and() */
+typedef struct
+{
+	Path	   *path;			/* IndexPath, BitmapAndPath, or BitmapOrPath */
+	List	   *quals;			/* the WHERE clauses it uses */
+	List	   *preds;			/* predicates of its partial index(es) */
+	Bitmapset  *clauseids;		/* quals+preds represented as a bitmapset */
+	bool		unclassifiable; /* has too many quals+preds to process? */
+} PathClauseUsage;
+
+/* Callback argument for ec_member_matches_indexcol */
+typedef struct
+{
+	IndexOptInfo *index;		/* index we're considering */
+	int			indexcol;		/* index column we want to match to */
+} ec_member_matches_arg;
+
+
+static void consider_index_join_clauses(PlannerInfo *root, RelOptInfo *rel,
+										IndexOptInfo *index,
+										IndexClauseSet *rclauseset,
+										IndexClauseSet *jclauseset,
+										IndexClauseSet *eclauseset,
+										List **bitindexpaths);
+static void consider_index_join_outer_rels(PlannerInfo *root, RelOptInfo *rel,
+										   IndexOptInfo *index,
+										   IndexClauseSet *rclauseset,
+										   IndexClauseSet *jclauseset,
+										   IndexClauseSet *eclauseset,
+										   List **bitindexpaths,
+										   List *indexjoinclauses,
+										   int considered_clauses,
+										   List **considered_relids);
+static void get_join_index_paths(PlannerInfo *root, RelOptInfo *rel,
+								 IndexOptInfo *index,
+								 IndexClauseSet *rclauseset,
+								 IndexClauseSet *jclauseset,
+								 IndexClauseSet *eclauseset,
+								 List **bitindexpaths,
+								 Relids relids,
+								 List **considered_relids);
+static bool eclass_already_used(EquivalenceClass *parent_ec, Relids oldrelids,
+								List *indexjoinclauses);
+static bool bms_equal_any(Relids relids, List *relids_list);
+static void get_index_paths(PlannerInfo *root, RelOptInfo *rel,
+							IndexOptInfo *index, IndexClauseSet *clauses,
+							List **bitindexpaths);
+static List *build_index_paths(PlannerInfo *root, RelOptInfo *rel,
+							   IndexOptInfo *index, IndexClauseSet *clauses,
+							   bool useful_predicate,
+							   ScanTypeControl scantype,
+							   bool *skip_nonnative_saop,
+							   bool *skip_lower_saop);
+static List *build_paths_for_OR(PlannerInfo *root, RelOptInfo *rel,
+								List *clauses, List *other_clauses);
+static List *generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel,
+									  List *clauses, List *other_clauses);
+static Path *choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel,
+							   List *paths);
+static int	path_usage_comparator(const void *a, const void *b);
+static Cost bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel,
+								 Path *ipath);
+static Cost bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel,
+								List *paths);
+static PathClauseUsage *classify_index_clause_usage(Path *path,
+													List **clauselist);
+static void find_indexpath_quals(Path *bitmapqual, List **quals, List **preds);
+static int	find_list_position(Node *node, List **nodelist);
+static bool check_index_only(RelOptInfo *rel, IndexOptInfo *index);
+static double get_loop_count(PlannerInfo *root, Index cur_relid, Relids outer_relids);
+static double adjust_rowcount_for_semijoins(PlannerInfo *root,
+											Index cur_relid,
+											Index outer_relid,
+											double rowcount);
+static double approximate_joinrel_size(PlannerInfo *root, Relids relids);
+static void match_restriction_clauses_to_index(PlannerInfo *root,
+											   IndexOptInfo *index,
+											   IndexClauseSet *clauseset);
+static void match_join_clauses_to_index(PlannerInfo *root,
+										RelOptInfo *rel, IndexOptInfo *index,
+										IndexClauseSet *clauseset,
+										List **joinorclauses);
+static void match_eclass_clauses_to_index(PlannerInfo *root,
+										  IndexOptInfo *index,
+										  IndexClauseSet *clauseset);
+static void match_clauses_to_index(PlannerInfo *root,
+								   List *clauses,
+								   IndexOptInfo *index,
+								   IndexClauseSet *clauseset);
+static void match_clause_to_index(PlannerInfo *root,
+								  RestrictInfo *rinfo,
+								  IndexOptInfo *index,
+								  IndexClauseSet *clauseset);
+static IndexClause *match_clause_to_indexcol(PlannerInfo *root,
+											 RestrictInfo *rinfo,
+											 int indexcol,
+											 IndexOptInfo *index);
+static IndexClause *match_boolean_index_clause(PlannerInfo *root,
+											   RestrictInfo *rinfo,
+											   int indexcol, IndexOptInfo *index);
+static IndexClause *match_opclause_to_indexcol(PlannerInfo *root,
+											   RestrictInfo *rinfo,
+											   int indexcol,
+											   IndexOptInfo *index);
+static IndexClause *match_funcclause_to_indexcol(PlannerInfo *root,
+												 RestrictInfo *rinfo,
+												 int indexcol,
+												 IndexOptInfo *index);
+static IndexClause *get_index_clause_from_support(PlannerInfo *root,
+												  RestrictInfo *rinfo,
+												  Oid funcid,
+												  int indexarg,
+												  int indexcol,
+												  IndexOptInfo *index);
+static IndexClause *match_saopclause_to_indexcol(PlannerInfo *root,
+												 RestrictInfo *rinfo,
+												 int indexcol,
+												 IndexOptInfo *index);
+static IndexClause *match_rowcompare_to_indexcol(PlannerInfo *root,
+												 RestrictInfo *rinfo,
+												 int indexcol,
+												 IndexOptInfo *index);
+static IndexClause *expand_indexqual_rowcompare(PlannerInfo *root,
+												RestrictInfo *rinfo,
+												int indexcol,
+												IndexOptInfo *index,
+												Oid expr_op,
+												bool var_on_left);
+static void match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys,
+									List **orderby_clauses_p,
+									List **clause_columns_p);
+static Expr *match_clause_to_ordering_op(IndexOptInfo *index,
+										 int indexcol, Expr *clause, Oid pk_opfamily);
+static bool ec_member_matches_indexcol(PlannerInfo *root, RelOptInfo *rel,
+									   EquivalenceClass *ec, EquivalenceMember *em,
+									   void *arg);
+
+
+/*
+ * create_index_paths()
+ *	  Generate all interesting index paths for the given relation.
+ *	  Candidate paths are added to the rel's pathlist (using add_path).
+ *
+ * To be considered for an index scan, an index must match one or more
+ * restriction clauses or join clauses from the query's qual condition,
+ * or match the query's ORDER BY condition, or have a predicate that
+ * matches the query's qual condition.
+ *
+ * There are two basic kinds of index scans.  A "plain" index scan uses
+ * only restriction clauses (possibly none at all) in its indexqual,
+ * so it can be applied in any context.  A "parameterized" index scan uses
+ * join clauses (plus restriction clauses, if available) in its indexqual.
+ * When joining such a scan to one of the relations supplying the other
+ * variables used in its indexqual, the parameterized scan must appear as
+ * the inner relation of a nestloop join; it can't be used on the outer side,
+ * nor in a merge or hash join.  In that context, values for the other rels'
+ * attributes are available and fixed during any one scan of the indexpath.
+ *
+ * An IndexPath is generated and submitted to add_path() for each plain or
+ * parameterized index scan this routine deems potentially interesting for
+ * the current query.
+ *
+ * 'rel' is the relation for which we want to generate index paths
+ *
+ * Note: check_index_predicates() must have been run previously for this rel.
+ *
+ * Note: in cases involving LATERAL references in the relation's tlist, it's
+ * possible that rel->lateral_relids is nonempty.  Currently, we include
+ * lateral_relids into the parameterization reported for each path, but don't
+ * take it into account otherwise.  The fact that any such rels *must* be
+ * available as parameter sources perhaps should influence our choices of
+ * index quals ... but for now, it doesn't seem worth troubling over.
+ * In particular, comments below about "unparameterized" paths should be read
+ * as meaning "unparameterized so far as the indexquals are concerned".
+ */
+void
+create_index_paths(PlannerInfo *root, RelOptInfo *rel)
+{
+	List	   *indexpaths;
+	List	   *bitindexpaths;
+	List	   *bitjoinpaths;
+	List	   *joinorclauses;
+	IndexClauseSet rclauseset;
+	IndexClauseSet jclauseset;
+	IndexClauseSet eclauseset;
+	ListCell   *lc;
+
+	/* Skip the whole mess if no indexes */
+	if (rel->indexlist == NIL)
+		return;
+
+	/* Bitmap paths are collected and then dealt with at the end */
+	bitindexpaths = bitjoinpaths = joinorclauses = NIL;
+
+	/* Examine each index in turn */
+	foreach(lc, rel->indexlist)
+	{
+		IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
+
+		/* Protect limited-size array in IndexClauseSets */
+		Assert(index->nkeycolumns <= INDEX_MAX_KEYS);
+
+		/*
+		 * Ignore partial indexes that do not match the query.
+		 * (generate_bitmap_or_paths() might be able to do something with
+		 * them, but that's of no concern here.)
+		 */
+		if (index->indpred != NIL && !index->predOK)
+			continue;
+
+		/*
+		 * Identify the restriction clauses that can match the index.
+		 */
+		MemSet(&rclauseset, 0, sizeof(rclauseset));
+		match_restriction_clauses_to_index(root, index, &rclauseset);
+
+		/*
+		 * Build index paths from the restriction clauses.  These will be
+		 * non-parameterized paths.  Plain paths go directly to add_path(),
+		 * bitmap paths are added to bitindexpaths to be handled below.
+		 */
+		get_index_paths(root, rel, index, &rclauseset,
+						&bitindexpaths);
+
+		/*
+		 * Identify the join clauses that can match the index.  For the moment
+		 * we keep them separate from the restriction clauses.  Note that this
+		 * step finds only "loose" join clauses that have not been merged into
+		 * EquivalenceClasses.  Also, collect join OR clauses for later.
+		 */
+		MemSet(&jclauseset, 0, sizeof(jclauseset));
+		match_join_clauses_to_index(root, rel, index,
+									&jclauseset, &joinorclauses);
+
+		/*
+		 * Look for EquivalenceClasses that can generate joinclauses matching
+		 * the index.
+		 */
+		MemSet(&eclauseset, 0, sizeof(eclauseset));
+		match_eclass_clauses_to_index(root, index,
+									  &eclauseset);
+
+		/*
+		 * If we found any plain or eclass join clauses, build parameterized
+		 * index paths using them.
+		 */
+		if (jclauseset.nonempty || eclauseset.nonempty)
+			consider_index_join_clauses(root, rel, index,
+										&rclauseset,
+										&jclauseset,
+										&eclauseset,
+										&bitjoinpaths);
+	}
+
+	/*
+	 * Generate BitmapOrPaths for any suitable OR-clauses present in the
+	 * restriction list.  Add these to bitindexpaths.
+	 */
+	indexpaths = generate_bitmap_or_paths(root, rel,
+										  rel->baserestrictinfo, NIL);
+	bitindexpaths = list_concat(bitindexpaths, indexpaths);
+
+	/*
+	 * Likewise, generate BitmapOrPaths for any suitable OR-clauses present in
+	 * the joinclause list.  Add these to bitjoinpaths.
+	 */
+	indexpaths = generate_bitmap_or_paths(root, rel,
+										  joinorclauses, rel->baserestrictinfo);
+	bitjoinpaths = list_concat(bitjoinpaths, indexpaths);
+
+	/*
+	 * If we found anything usable, generate a BitmapHeapPath for the most
+	 * promising combination of restriction bitmap index paths.  Note there
+	 * will be only one such path no matter how many indexes exist.  This
+	 * should be sufficient since there's basically only one figure of merit
+	 * (total cost) for such a path.
+	 */
+	if (bitindexpaths != NIL)
+	{
+		Path	   *bitmapqual;
+		BitmapHeapPath *bpath;
+
+		bitmapqual = choose_bitmap_and(root, rel, bitindexpaths);
+		bpath = create_bitmap_heap_path(root, rel, bitmapqual,
+										rel->lateral_relids, 1.0, 0);
+		add_path(rel, (Path *) bpath);
+
+		/* create a partial bitmap heap path */
+		if (rel->consider_parallel && rel->lateral_relids == NULL)
+			create_partial_bitmap_paths(root, rel, bitmapqual);
+	}
+
+	/*
+	 * Likewise, if we found anything usable, generate BitmapHeapPaths for the
+	 * most promising combinations of join bitmap index paths.  Our strategy
+	 * is to generate one such path for each distinct parameterization seen
+	 * among the available bitmap index paths.  This may look pretty
+	 * expensive, but usually there won't be very many distinct
+	 * parameterizations.  (This logic is quite similar to that in
+	 * consider_index_join_clauses, but we're working with whole paths not
+	 * individual clauses.)
+	 */
+	if (bitjoinpaths != NIL)
+	{
+		List	   *all_path_outers;
+		ListCell   *lc;
+
+		/* Identify each distinct parameterization seen in bitjoinpaths */
+		all_path_outers = NIL;
+		foreach(lc, bitjoinpaths)
+		{
+			Path	   *path = (Path *) lfirst(lc);
+			Relids		required_outer = PATH_REQ_OUTER(path);
+
+			if (!bms_equal_any(required_outer, all_path_outers))
+				all_path_outers = lappend(all_path_outers, required_outer);
+		}
+
+		/* Now, for each distinct parameterization set ... */
+		foreach(lc, all_path_outers)
+		{
+			Relids		max_outers = (Relids) lfirst(lc);
+			List	   *this_path_set;
+			Path	   *bitmapqual;
+			Relids		required_outer;
+			double		loop_count;
+			BitmapHeapPath *bpath;
+			ListCell   *lcp;
+
+			/* Identify all the bitmap join paths needing no more than that */
+			this_path_set = NIL;
+			foreach(lcp, bitjoinpaths)
+			{
+				Path	   *path = (Path *) lfirst(lcp);
+
+				if (bms_is_subset(PATH_REQ_OUTER(path), max_outers))
+					this_path_set = lappend(this_path_set, path);
+			}
+
+			/*
+			 * Add in restriction bitmap paths, since they can be used
+			 * together with any join paths.
+			 */
+			this_path_set = list_concat(this_path_set, bitindexpaths);
+
+			/* Select best AND combination for this parameterization */
+			bitmapqual = choose_bitmap_and(root, rel, this_path_set);
+
+			/* And push that path into the mix */
+			required_outer = PATH_REQ_OUTER(bitmapqual);
+			loop_count = get_loop_count(root, rel->relid, required_outer);
+			bpath = create_bitmap_heap_path(root, rel, bitmapqual,
+											required_outer, loop_count, 0);
+			add_path(rel, (Path *) bpath);
+		}
+	}
+}
+
+/*
+ * consider_index_join_clauses
+ *	  Given sets of join clauses for an index, decide which parameterized
+ *	  index paths to build.
+ *
+ * Plain indexpaths are sent directly to add_path, while potential
+ * bitmap indexpaths are added to *bitindexpaths for later processing.
+ *
+ * 'rel' is the index's heap relation
+ * 'index' is the index for which we want to generate paths
+ * 'rclauseset' is the collection of indexable restriction clauses
+ * 'jclauseset' is the collection of indexable simple join clauses
+ * 'eclauseset' is the collection of indexable clauses from EquivalenceClasses
+ * '*bitindexpaths' is the list to add bitmap paths to
+ */
+static void
+consider_index_join_clauses(PlannerInfo *root, RelOptInfo *rel,
+							IndexOptInfo *index,
+							IndexClauseSet *rclauseset,
+							IndexClauseSet *jclauseset,
+							IndexClauseSet *eclauseset,
+							List **bitindexpaths)
+{
+	int			considered_clauses = 0;
+	List	   *considered_relids = NIL;
+	int			indexcol;
+
+	/*
+	 * The strategy here is to identify every potentially useful set of outer
+	 * rels that can provide indexable join clauses.  For each such set,
+	 * select all the join clauses available from those outer rels, add on all
+	 * the indexable restriction clauses, and generate plain and/or bitmap
+	 * index paths for that set of clauses.  This is based on the assumption
+	 * that it's always better to apply a clause as an indexqual than as a
+	 * filter (qpqual); which is where an available clause would end up being
+	 * applied if we omit it from the indexquals.
+	 *
+	 * This looks expensive, but in most practical cases there won't be very
+	 * many distinct sets of outer rels to consider.  As a safety valve when
+	 * that's not true, we use a heuristic: limit the number of outer rel sets
+	 * considered to a multiple of the number of clauses considered.  (We'll
+	 * always consider using each individual join clause, though.)
+	 *
+	 * For simplicity in selecting relevant clauses, we represent each set of
+	 * outer rels as a maximum set of clause_relids --- that is, the indexed
+	 * relation itself is also included in the relids set.  considered_relids
+	 * lists all relids sets we've already tried.
+	 */
+	for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
+	{
+		/* Consider each applicable simple join clause */
+		considered_clauses += list_length(jclauseset->indexclauses[indexcol]);
+		consider_index_join_outer_rels(root, rel, index,
+									   rclauseset, jclauseset, eclauseset,
+									   bitindexpaths,
+									   jclauseset->indexclauses[indexcol],
+									   considered_clauses,
+									   &considered_relids);
+		/* Consider each applicable eclass join clause */
+		considered_clauses += list_length(eclauseset->indexclauses[indexcol]);
+		consider_index_join_outer_rels(root, rel, index,
+									   rclauseset, jclauseset, eclauseset,
+									   bitindexpaths,
+									   eclauseset->indexclauses[indexcol],
+									   considered_clauses,
+									   &considered_relids);
+	}
+}
+
+/*
+ * consider_index_join_outer_rels
+ *	  Generate parameterized paths based on clause relids in the clause list.
+ *
+ * Workhorse for consider_index_join_clauses; see notes therein for rationale.
+ *
+ * 'rel', 'index', 'rclauseset', 'jclauseset', 'eclauseset', and
+ *		'bitindexpaths' as above
+ * 'indexjoinclauses' is a list of IndexClauses for join clauses
+ * 'considered_clauses' is the total number of clauses considered (so far)
+ * '*considered_relids' is a list of all relids sets already considered
+ */
+static void
+consider_index_join_outer_rels(PlannerInfo *root, RelOptInfo *rel,
+							   IndexOptInfo *index,
+							   IndexClauseSet *rclauseset,
+							   IndexClauseSet *jclauseset,
+							   IndexClauseSet *eclauseset,
+							   List **bitindexpaths,
+							   List *indexjoinclauses,
+							   int considered_clauses,
+							   List **considered_relids)
+{
+	ListCell   *lc;
+
+	/* Examine relids of each joinclause in the given list */
+	foreach(lc, indexjoinclauses)
+	{
+		IndexClause *iclause = (IndexClause *) lfirst(lc);
+		Relids		clause_relids = iclause->rinfo->clause_relids;
+		EquivalenceClass *parent_ec = iclause->rinfo->parent_ec;
+		int			num_considered_relids;
+
+		/* If we already tried its relids set, no need to do so again */
+		if (bms_equal_any(clause_relids, *considered_relids))
+			continue;
+
+		/*
+		 * Generate the union of this clause's relids set with each
+		 * previously-tried set.  This ensures we try this clause along with
+		 * every interesting subset of previous clauses.  However, to avoid
+		 * exponential growth of planning time when there are many clauses,
+		 * limit the number of relid sets accepted to 10 * considered_clauses.
+		 *
+		 * Note: get_join_index_paths appends entries to *considered_relids,
+		 * but we do not need to visit such newly-added entries within this
+		 * loop, so we don't use foreach() here.  No real harm would be done
+		 * if we did visit them, since the subset check would reject them; but
+		 * it would waste some cycles.
+		 */
+		num_considered_relids = list_length(*considered_relids);
+		for (int pos = 0; pos < num_considered_relids; pos++)
+		{
+			Relids		oldrelids = (Relids) list_nth(*considered_relids, pos);
+
+			/*
+			 * If either is a subset of the other, no new set is possible.
+			 * This isn't a complete test for redundancy, but it's easy and
+			 * cheap.  get_join_index_paths will check more carefully if we
+			 * already generated the same relids set.
+			 */
+			if (bms_subset_compare(clause_relids, oldrelids) != BMS_DIFFERENT)
+				continue;
+
+			/*
+			 * If this clause was derived from an equivalence class, the
+			 * clause list may contain other clauses derived from the same
+			 * eclass.  We should not consider that combining this clause with
+			 * one of those clauses generates a usefully different
+			 * parameterization; so skip if any clause derived from the same
+			 * eclass would already have been included when using oldrelids.
+			 */
+			if (parent_ec &&
+				eclass_already_used(parent_ec, oldrelids,
+									indexjoinclauses))
+				continue;
+
+			/*
+			 * If the number of relid sets considered exceeds our heuristic
+			 * limit, stop considering combinations of clauses.  We'll still
+			 * consider the current clause alone, though (below this loop).
+			 */
+			if (list_length(*considered_relids) >= 10 * considered_clauses)
+				break;
+
+			/* OK, try the union set */
+			get_join_index_paths(root, rel, index,
+								 rclauseset, jclauseset, eclauseset,
+								 bitindexpaths,
+								 bms_union(clause_relids, oldrelids),
+								 considered_relids);
+		}
+
+		/* Also try this set of relids by itself */
+		get_join_index_paths(root, rel, index,
+							 rclauseset, jclauseset, eclauseset,
+							 bitindexpaths,
+							 clause_relids,
+							 considered_relids);
+	}
+}
+
+/*
+ * get_join_index_paths
+ *	  Generate index paths using clauses from the specified outer relations.
+ *	  In addition to generating paths, relids is added to *considered_relids
+ *	  if not already present.
+ *
+ * Workhorse for consider_index_join_clauses; see notes therein for rationale.
+ *
+ * 'rel', 'index', 'rclauseset', 'jclauseset', 'eclauseset',
+ *		'bitindexpaths', 'considered_relids' as above
+ * 'relids' is the current set of relids to consider (the target rel plus
+ *		one or more outer rels)
+ */
+static void
+get_join_index_paths(PlannerInfo *root, RelOptInfo *rel,
+					 IndexOptInfo *index,
+					 IndexClauseSet *rclauseset,
+					 IndexClauseSet *jclauseset,
+					 IndexClauseSet *eclauseset,
+					 List **bitindexpaths,
+					 Relids relids,
+					 List **considered_relids)
+{
+	IndexClauseSet clauseset;
+	int			indexcol;
+
+	/* If we already considered this relids set, don't repeat the work */
+	if (bms_equal_any(relids, *considered_relids))
+		return;
+
+	/* Identify indexclauses usable with this relids set */
+	MemSet(&clauseset, 0, sizeof(clauseset));
+
+	for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
+	{
+		ListCell   *lc;
+
+		/* First find applicable simple join clauses */
+		foreach(lc, jclauseset->indexclauses[indexcol])
+		{
+			IndexClause *iclause = (IndexClause *) lfirst(lc);
+
+			if (bms_is_subset(iclause->rinfo->clause_relids, relids))
+				clauseset.indexclauses[indexcol] =
+					lappend(clauseset.indexclauses[indexcol], iclause);
+		}
+
+		/*
+		 * Add applicable eclass join clauses.  The clauses generated for each
+		 * column are redundant (cf generate_implied_equalities_for_column),
+		 * so we need at most one.  This is the only exception to the general
+		 * rule of using all available index clauses.
+		 */
+		foreach(lc, eclauseset->indexclauses[indexcol])
+		{
+			IndexClause *iclause = (IndexClause *) lfirst(lc);
+
+			if (bms_is_subset(iclause->rinfo->clause_relids, relids))
+			{
+				clauseset.indexclauses[indexcol] =
+					lappend(clauseset.indexclauses[indexcol], iclause);
+				break;
+			}
+		}
+
+		/* Add restriction clauses */
+		clauseset.indexclauses[indexcol] =
+			list_concat(clauseset.indexclauses[indexcol],
+						rclauseset->indexclauses[indexcol]);
+
+		if (clauseset.indexclauses[indexcol] != NIL)
+			clauseset.nonempty = true;
+	}
+
+	/* We should have found something, else caller passed silly relids */
+	Assert(clauseset.nonempty);
+
+	/* Build index path(s) using the collected set of clauses */
+	get_index_paths(root, rel, index, &clauseset, bitindexpaths);
+
+	/*
+	 * Remember we considered paths for this set of relids.
+	 */
+	*considered_relids = lappend(*considered_relids, relids);
+}
+
+/*
+ * eclass_already_used
+ *		True if any join clause usable with oldrelids was generated from
+ *		the specified equivalence class.
+ */
+static bool
+eclass_already_used(EquivalenceClass *parent_ec, Relids oldrelids,
+					List *indexjoinclauses)
+{
+	ListCell   *lc;
+
+	foreach(lc, indexjoinclauses)
+	{
+		IndexClause *iclause = (IndexClause *) lfirst(lc);
+		RestrictInfo *rinfo = iclause->rinfo;
+
+		if (rinfo->parent_ec == parent_ec &&
+			bms_is_subset(rinfo->clause_relids, oldrelids))
+			return true;
+	}
+	return false;
+}
+
+/*
+ * bms_equal_any
+ *		True if relids is bms_equal to any member of relids_list
+ *
+ * Perhaps this should be in bitmapset.c someday.
+ */
+static bool
+bms_equal_any(Relids relids, List *relids_list)
+{
+	ListCell   *lc;
+
+	foreach(lc, relids_list)
+	{
+		if (bms_equal(relids, (Relids) lfirst(lc)))
+			return true;
+	}
+	return false;
+}
+
+
+/*
+ * get_index_paths
+ *	  Given an index and a set of index clauses for it, construct IndexPaths.
+ *
+ * Plain indexpaths are sent directly to add_path, while potential
+ * bitmap indexpaths are added to *bitindexpaths for later processing.
+ *
+ * This is a fairly simple frontend to build_index_paths().  Its reason for
+ * existence is mainly to handle ScalarArrayOpExpr quals properly.  If the
+ * index AM supports them natively, we should just include them in simple
+ * index paths.  If not, we should exclude them while building simple index
+ * paths, and then make a separate attempt to include them in bitmap paths.
+ * Furthermore, we should consider excluding lower-order ScalarArrayOpExpr
+ * quals so as to create ordered paths.
+ */
+static void
+get_index_paths(PlannerInfo *root, RelOptInfo *rel,
+				IndexOptInfo *index, IndexClauseSet *clauses,
+				List **bitindexpaths)
+{
+	List	   *indexpaths;
+	bool		skip_nonnative_saop = false;
+	bool		skip_lower_saop = false;
+	ListCell   *lc;
+
+	/*
+	 * Build simple index paths using the clauses.  Allow ScalarArrayOpExpr
+	 * clauses only if the index AM supports them natively, and skip any such
+	 * clauses for index columns after the first (so that we produce ordered
+	 * paths if possible).
+	 */
+	indexpaths = build_index_paths(root, rel,
+								   index, clauses,
+								   index->predOK,
+								   ST_ANYSCAN,
+								   &skip_nonnative_saop,
+								   &skip_lower_saop);
+
+	/*
+	 * If we skipped any lower-order ScalarArrayOpExprs on an index with an AM
+	 * that supports them, then try again including those clauses.  This will
+	 * produce paths with more selectivity but no ordering.
+	 */
+	if (skip_lower_saop)
+	{
+		indexpaths = list_concat(indexpaths,
+								 build_index_paths(root, rel,
+												   index, clauses,
+												   index->predOK,
+												   ST_ANYSCAN,
+												   &skip_nonnative_saop,
+												   NULL));
+	}
+
+	/*
+	 * Submit all the ones that can form plain IndexScan plans to add_path. (A
+	 * plain IndexPath can represent either a plain IndexScan or an
+	 * IndexOnlyScan, but for our purposes here that distinction does not
+	 * matter.  However, some of the indexes might support only bitmap scans,
+	 * and those we mustn't submit to add_path here.)
+	 *
+	 * Also, pick out the ones that are usable as bitmap scans.  For that, we
+	 * must discard indexes that don't support bitmap scans, and we also are
+	 * only interested in paths that have some selectivity; we should discard
+	 * anything that was generated solely for ordering purposes.
+	 */
+	foreach(lc, indexpaths)
+	{
+		IndexPath  *ipath = (IndexPath *) lfirst(lc);
+
+		if (index->amhasgettuple)
+			add_path(rel, (Path *) ipath);
+
+		if (index->amhasgetbitmap &&
+			(ipath->path.pathkeys == NIL ||
+			 ipath->indexselectivity < 1.0))
+			*bitindexpaths = lappend(*bitindexpaths, ipath);
+	}
+
+	/*
+	 * If there were ScalarArrayOpExpr clauses that the index can't handle
+	 * natively, generate bitmap scan paths relying on executor-managed
+	 * ScalarArrayOpExpr.
+	 */
+	if (skip_nonnative_saop)
+	{
+		indexpaths = build_index_paths(root, rel,
+									   index, clauses,
+									   false,
+									   ST_BITMAPSCAN,
+									   NULL,
+									   NULL);
+		*bitindexpaths = list_concat(*bitindexpaths, indexpaths);
+	}
+}
+
+/*
+ * build_index_paths
+ *	  Given an index and a set of index clauses for it, construct zero
+ *	  or more IndexPaths. It also constructs zero or more partial IndexPaths.
+ *
+ * We return a list of paths because (1) this routine checks some cases
+ * that should cause us to not generate any IndexPath, and (2) in some
+ * cases we want to consider both a forward and a backward scan, so as
+ * to obtain both sort orders.  Note that the paths are just returned
+ * to the caller and not immediately fed to add_path().
+ *
+ * At top level, useful_predicate should be exactly the index's predOK flag
+ * (ie, true if it has a predicate that was proven from the restriction
+ * clauses).  When working on an arm of an OR clause, useful_predicate
+ * should be true if the predicate required the current OR list to be proven.
+ * Note that this routine should never be called at all if the index has an
+ * unprovable predicate.
+ *
+ * scantype indicates whether we want to create plain indexscans, bitmap
+ * indexscans, or both.  When it's ST_BITMAPSCAN, we will not consider
+ * index ordering while deciding if a Path is worth generating.
+ *
+ * If skip_nonnative_saop is non-NULL, we ignore ScalarArrayOpExpr clauses
+ * unless the index AM supports them directly, and we set *skip_nonnative_saop
+ * to true if we found any such clauses (caller must initialize the variable
+ * to false).  If it's NULL, we do not ignore ScalarArrayOpExpr clauses.
+ *
+ * If skip_lower_saop is non-NULL, we ignore ScalarArrayOpExpr clauses for
+ * non-first index columns, and we set *skip_lower_saop to true if we found
+ * any such clauses (caller must initialize the variable to false).  If it's
+ * NULL, we do not ignore non-first ScalarArrayOpExpr clauses, but they will
+ * result in considering the scan's output to be unordered.
+ *
+ * 'rel' is the index's heap relation
+ * 'index' is the index for which we want to generate paths
+ * 'clauses' is the collection of indexable clauses (IndexClause nodes)
+ * 'useful_predicate' indicates whether the index has a useful predicate
+ * 'scantype' indicates whether we need plain or bitmap scan support
+ * 'skip_nonnative_saop' indicates whether to accept SAOP if index AM doesn't
+ * 'skip_lower_saop' indicates whether to accept non-first-column SAOP
+ */
+static List *
+build_index_paths(PlannerInfo *root, RelOptInfo *rel,
+				  IndexOptInfo *index, IndexClauseSet *clauses,
+				  bool useful_predicate,
+				  ScanTypeControl scantype,
+				  bool *skip_nonnative_saop,
+				  bool *skip_lower_saop)
+{
+	List	   *result = NIL;
+	IndexPath  *ipath;
+	List	   *index_clauses;
+	Relids		outer_relids;
+	double		loop_count;
+	List	   *orderbyclauses;
+	List	   *orderbyclausecols;
+	List	   *index_pathkeys;
+	List	   *useful_pathkeys;
+	bool		found_lower_saop_clause;
+	bool		pathkeys_possibly_useful;
+	bool		index_is_ordered;
+	bool		index_only_scan;
+	int			indexcol;
+
+	/*
+	 * Check that index supports the desired scan type(s)
+	 */
+	switch (scantype)
+	{
+		case ST_INDEXSCAN:
+			if (!index->amhasgettuple)
+				return NIL;
+			break;
+		case ST_BITMAPSCAN:
+			if (!index->amhasgetbitmap)
+				return NIL;
+			break;
+		case ST_ANYSCAN:
+			/* either or both are OK */
+			break;
+	}
+
+	/*
+	 * 1. Combine the per-column IndexClause lists into an overall list.
+	 *
+	 * In the resulting list, clauses are ordered by index key, so that the
+	 * column numbers form a nondecreasing sequence.  (This order is depended
+	 * on by btree and possibly other places.)  The list can be empty, if the
+	 * index AM allows that.
+	 *
+	 * found_lower_saop_clause is set true if we accept a ScalarArrayOpExpr
+	 * index clause for a non-first index column.  This prevents us from
+	 * assuming that the scan result is ordered.  (Actually, the result is
+	 * still ordered if there are equality constraints for all earlier
+	 * columns, but it seems too expensive and non-modular for this code to be
+	 * aware of that refinement.)
+	 *
+	 * We also build a Relids set showing which outer rels are required by the
+	 * selected clauses.  Any lateral_relids are included in that, but not
+	 * otherwise accounted for.
+	 */
+	index_clauses = NIL;
+	found_lower_saop_clause = false;
+	outer_relids = bms_copy(rel->lateral_relids);
+	for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
+	{
+		ListCell   *lc;
+
+		foreach(lc, clauses->indexclauses[indexcol])
+		{
+			IndexClause *iclause = (IndexClause *) lfirst(lc);
+			RestrictInfo *rinfo = iclause->rinfo;
+
+			/* We might need to omit ScalarArrayOpExpr clauses */
+			if (IsA(rinfo->clause, ScalarArrayOpExpr))
+			{
+				if (!index->amsearcharray)
+				{
+					if (skip_nonnative_saop)
+					{
+						/* Ignore because not supported by index */
+						*skip_nonnative_saop = true;
+						continue;
+					}
+					/* Caller had better intend this only for bitmap scan */
+					Assert(scantype == ST_BITMAPSCAN);
+				}
+				if (indexcol > 0)
+				{
+					if (skip_lower_saop)
+					{
+						/* Caller doesn't want to lose index ordering */
+						*skip_lower_saop = true;
+						continue;
+					}
+					found_lower_saop_clause = true;
+				}
+			}
+
+			/* OK to include this clause */
+			index_clauses = lappend(index_clauses, iclause);
+			outer_relids = bms_add_members(outer_relids,
+										   rinfo->clause_relids);
+		}
+
+		/*
+		 * If no clauses match the first index column, check for amoptionalkey
+		 * restriction.  We can't generate a scan over an index with
+		 * amoptionalkey = false unless there's at least one index clause.
+		 * (When working on columns after the first, this test cannot fail. It
+		 * is always okay for columns after the first to not have any
+		 * clauses.)
+		 */
+		if (index_clauses == NIL && !index->amoptionalkey)
+			return NIL;
+	}
+
+	/* We do not want the index's rel itself listed in outer_relids */
+	outer_relids = bms_del_member(outer_relids, rel->relid);
+	/* Enforce convention that outer_relids is exactly NULL if empty */
+	if (bms_is_empty(outer_relids))
+		outer_relids = NULL;
+
+	/* Compute loop_count for cost estimation purposes */
+	loop_count = get_loop_count(root, rel->relid, outer_relids);
+
+	/*
+	 * 2. Compute pathkeys describing index's ordering, if any, then see how
+	 * many of them are actually useful for this query.  This is not relevant
+	 * if we are only trying to build bitmap indexscans, nor if we have to
+	 * assume the scan is unordered.
+	 */
+	pathkeys_possibly_useful = (scantype != ST_BITMAPSCAN &&
+								!found_lower_saop_clause &&
+								has_useful_pathkeys(root, rel));
+	index_is_ordered = (index->sortopfamily != NULL);
+	if (index_is_ordered && pathkeys_possibly_useful)
+	{
+		index_pathkeys = build_index_pathkeys(root, index,
+											  ForwardScanDirection);
+		useful_pathkeys = truncate_useless_pathkeys(root, rel,
+													index_pathkeys);
+		orderbyclauses = NIL;
+		orderbyclausecols = NIL;
+	}
+	else if (index->amcanorderbyop && pathkeys_possibly_useful)
+	{
+		/* see if we can generate ordering operators for query_pathkeys */
+		match_pathkeys_to_index(index, root->query_pathkeys,
+								&orderbyclauses,
+								&orderbyclausecols);
+		if (orderbyclauses)
+			useful_pathkeys = root->query_pathkeys;
+		else
+			useful_pathkeys = NIL;
+	}
+	else
+	{
+		useful_pathkeys = NIL;
+		orderbyclauses = NIL;
+		orderbyclausecols = NIL;
+	}
+
+	/*
+	 * 3. Check if an index-only scan is possible.  If we're not building
+	 * plain indexscans, this isn't relevant since bitmap scans don't support
+	 * index data retrieval anyway.
+	 */
+	index_only_scan = (scantype != ST_BITMAPSCAN &&
+					   check_index_only(rel, index));
+
+	/*
+	 * 4. Generate an indexscan path if there are relevant restriction clauses
+	 * in the current clauses, OR the index ordering is potentially useful for
+	 * later merging or final output ordering, OR the index has a useful
+	 * predicate, OR an index-only scan is possible.
+	 */
+	if (index_clauses != NIL || useful_pathkeys != NIL || useful_predicate ||
+		index_only_scan)
+	{
+		ipath = create_index_path(root, index,
+								  index_clauses,
+								  orderbyclauses,
+								  orderbyclausecols,
+								  useful_pathkeys,
+								  index_is_ordered ?
+								  ForwardScanDirection :
+								  NoMovementScanDirection,
+								  index_only_scan,
+								  outer_relids,
+								  loop_count,
+								  false);
+		result = lappend(result, ipath);
+
+		/*
+		 * If appropriate, consider parallel index scan.  We don't allow
+		 * parallel index scan for bitmap index scans.
+		 */
+		if (index->amcanparallel &&
+			rel->consider_parallel && outer_relids == NULL &&
+			scantype != ST_BITMAPSCAN)
+		{
+			ipath = create_index_path(root, index,
+									  index_clauses,
+									  orderbyclauses,
+									  orderbyclausecols,
+									  useful_pathkeys,
+									  index_is_ordered ?
+									  ForwardScanDirection :
+									  NoMovementScanDirection,
+									  index_only_scan,
+									  outer_relids,
+									  loop_count,
+									  true);
+
+			/*
+			 * if, after costing the path, we find that it's not worth using
+			 * parallel workers, just free it.
+			 */
+			if (ipath->path.parallel_workers > 0)
+				add_partial_path(rel, (Path *) ipath);
+			else
+				pfree(ipath);
+		}
+	}
+
+	/*
+	 * 5. If the index is ordered, a backwards scan might be interesting.
+	 */
+	if (index_is_ordered && pathkeys_possibly_useful)
+	{
+		index_pathkeys = build_index_pathkeys(root, index,
+											  BackwardScanDirection);
+		useful_pathkeys = truncate_useless_pathkeys(root, rel,
+													index_pathkeys);
+		if (useful_pathkeys != NIL)
+		{
+			ipath = create_index_path(root, index,
+									  index_clauses,
+									  NIL,
+									  NIL,
+									  useful_pathkeys,
+									  BackwardScanDirection,
+									  index_only_scan,
+									  outer_relids,
+									  loop_count,
+									  false);
+			result = lappend(result, ipath);
+
+			/* If appropriate, consider parallel index scan */
+			if (index->amcanparallel &&
+				rel->consider_parallel && outer_relids == NULL &&
+				scantype != ST_BITMAPSCAN)
+			{
+				ipath = create_index_path(root, index,
+										  index_clauses,
+										  NIL,
+										  NIL,
+										  useful_pathkeys,
+										  BackwardScanDirection,
+										  index_only_scan,
+										  outer_relids,
+										  loop_count,
+										  true);
+
+				/*
+				 * if, after costing the path, we find that it's not worth
+				 * using parallel workers, just free it.
+				 */
+				if (ipath->path.parallel_workers > 0)
+					add_partial_path(rel, (Path *) ipath);
+				else
+					pfree(ipath);
+			}
+		}
+	}
+
+	return result;
+}
+
+/*
+ * build_paths_for_OR
+ *	  Given a list of restriction clauses from one arm of an OR clause,
+ *	  construct all matching IndexPaths for the relation.
+ *
+ * Here we must scan all indexes of the relation, since a bitmap OR tree
+ * can use multiple indexes.
+ *
+ * The caller actually supplies two lists of restriction clauses: some
+ * "current" ones and some "other" ones.  Both lists can be used freely
+ * to match keys of the index, but an index must use at least one of the
+ * "current" clauses to be considered usable.  The motivation for this is
+ * examples like
+ *		WHERE (x = 42) AND (... OR (y = 52 AND z = 77) OR ....)
+ * While we are considering the y/z subclause of the OR, we can use "x = 42"
+ * as one of the available index conditions; but we shouldn't match the
+ * subclause to any index on x alone, because such a Path would already have
+ * been generated at the upper level.  So we could use an index on x,y,z
+ * or an index on x,y for the OR subclause, but not an index on just x.
+ * When dealing with a partial index, a match of the index predicate to
+ * one of the "current" clauses also makes the index usable.
+ *
+ * 'rel' is the relation for which we want to generate index paths
+ * 'clauses' is the current list of clauses (RestrictInfo nodes)
+ * 'other_clauses' is the list of additional upper-level clauses
+ */
+static List *
+build_paths_for_OR(PlannerInfo *root, RelOptInfo *rel,
+				   List *clauses, List *other_clauses)
+{
+	List	   *result = NIL;
+	List	   *all_clauses = NIL;	/* not computed till needed */
+	ListCell   *lc;
+
+	foreach(lc, rel->indexlist)
+	{
+		IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
+		IndexClauseSet clauseset;
+		List	   *indexpaths;
+		bool		useful_predicate;
+
+		/* Ignore index if it doesn't support bitmap scans */
+		if (!index->amhasgetbitmap)
+			continue;
+
+		/*
+		 * Ignore partial indexes that do not match the query.  If a partial
+		 * index is marked predOK then we know it's OK.  Otherwise, we have to
+		 * test whether the added clauses are sufficient to imply the
+		 * predicate. If so, we can use the index in the current context.
+		 *
+		 * We set useful_predicate to true iff the predicate was proven using
+		 * the current set of clauses.  This is needed to prevent matching a
+		 * predOK index to an arm of an OR, which would be a legal but
+		 * pointlessly inefficient plan.  (A better plan will be generated by
+		 * just scanning the predOK index alone, no OR.)
+		 */
+		useful_predicate = false;
+		if (index->indpred != NIL)
+		{
+			if (index->predOK)
+			{
+				/* Usable, but don't set useful_predicate */
+			}
+			else
+			{
+				/* Form all_clauses if not done already */
+				if (all_clauses == NIL)
+					all_clauses = list_concat_copy(clauses, other_clauses);
+
+				if (!predicate_implied_by(index->indpred, all_clauses, false))
+					continue;	/* can't use it at all */
+
+				if (!predicate_implied_by(index->indpred, other_clauses, false))
+					useful_predicate = true;
+			}
+		}
+
+		/*
+		 * Identify the restriction clauses that can match the index.
+		 */
+		MemSet(&clauseset, 0, sizeof(clauseset));
+		match_clauses_to_index(root, clauses, index, &clauseset);
+
+		/*
+		 * If no matches so far, and the index predicate isn't useful, we
+		 * don't want it.
+		 */
+		if (!clauseset.nonempty && !useful_predicate)
+			continue;
+
+		/*
+		 * Add "other" restriction clauses to the clauseset.
+		 */
+		match_clauses_to_index(root, other_clauses, index, &clauseset);
+
+		/*
+		 * Construct paths if possible.
+		 */
+		indexpaths = build_index_paths(root, rel,
+									   index, &clauseset,
+									   useful_predicate,
+									   ST_BITMAPSCAN,
+									   NULL,
+									   NULL);
+		result = list_concat(result, indexpaths);
+	}
+
+	return result;
+}
+
+/*
+ * generate_bitmap_or_paths
+ *		Look through the list of clauses to find OR clauses, and generate
+ *		a BitmapOrPath for each one we can handle that way.  Return a list
+ *		of the generated BitmapOrPaths.
+ *
+ * other_clauses is a list of additional clauses that can be assumed true
+ * for the purpose of generating indexquals, but are not to be searched for
+ * ORs.  (See build_paths_for_OR() for motivation.)
+ */
+static List *
+generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel,
+						 List *clauses, List *other_clauses)
+{
+	List	   *result = NIL;
+	List	   *all_clauses;
+	ListCell   *lc;
+
+	/*
+	 * We can use both the current and other clauses as context for
+	 * build_paths_for_OR; no need to remove ORs from the lists.
+	 */
+	all_clauses = list_concat_copy(clauses, other_clauses);
+
+	foreach(lc, clauses)
+	{
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
+		List	   *pathlist;
+		Path	   *bitmapqual;
+		ListCell   *j;
+
+		/* Ignore RestrictInfos that aren't ORs */
+		if (!restriction_is_or_clause(rinfo))
+			continue;
+
+		/*
+		 * We must be able to match at least one index to each of the arms of
+		 * the OR, else we can't use it.
+		 */
+		pathlist = NIL;
+		foreach(j, ((BoolExpr *) rinfo->orclause)->args)
+		{
+			Node	   *orarg = (Node *) lfirst(j);
+			List	   *indlist;
+
+			/* OR arguments should be ANDs or sub-RestrictInfos */
+			if (is_andclause(orarg))
+			{
+				List	   *andargs = ((BoolExpr *) orarg)->args;
+
+				indlist = build_paths_for_OR(root, rel,
+											 andargs,
+											 all_clauses);
+
+				/* Recurse in case there are sub-ORs */
+				indlist = list_concat(indlist,
+									  generate_bitmap_or_paths(root, rel,
+															   andargs,
+															   all_clauses));
+			}
+			else
+			{
+				RestrictInfo *rinfo = castNode(RestrictInfo, orarg);
+				List	   *orargs;
+
+				Assert(!restriction_is_or_clause(rinfo));
+				orargs = list_make1(rinfo);
+
+				indlist = build_paths_for_OR(root, rel,
+											 orargs,
+											 all_clauses);
+			}
+
+			/*
+			 * If nothing matched this arm, we can't do anything with this OR
+			 * clause.
+			 */
+			if (indlist == NIL)
+			{
+				pathlist = NIL;
+				break;
+			}
+
+			/*
+			 * OK, pick the most promising AND combination, and add it to
+			 * pathlist.
+			 */
+			bitmapqual = choose_bitmap_and(root, rel, indlist);
+			pathlist = lappend(pathlist, bitmapqual);
+		}
+
+		/*
+		 * If we have a match for every arm, then turn them into a
+		 * BitmapOrPath, and add to result list.
+		 */
+		if (pathlist != NIL)
+		{
+			bitmapqual = (Path *) create_bitmap_or_path(root, rel, pathlist);
+			result = lappend(result, bitmapqual);
+		}
+	}
+
+	return result;
+}
+
+
+/*
+ * choose_bitmap_and
+ *		Given a nonempty list of bitmap paths, AND them into one path.
+ *
+ * This is a nontrivial decision since we can legally use any subset of the
+ * given path set.  We want to choose a good tradeoff between selectivity
+ * and cost of computing the bitmap.
+ *
+ * The result is either a single one of the inputs, or a BitmapAndPath
+ * combining multiple inputs.
+ */
+static Path *
+choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel, List *paths)
+{
+	int			npaths = list_length(paths);
+	PathClauseUsage **pathinfoarray;
+	PathClauseUsage *pathinfo;
+	List	   *clauselist;
+	List	   *bestpaths = NIL;
+	Cost		bestcost = 0;
+	int			i,
+				j;
+	ListCell   *l;
+
+	Assert(npaths > 0);			/* else caller error */
+	if (npaths == 1)
+		return (Path *) linitial(paths);	/* easy case */
+
+	/*
+	 * In theory we should consider every nonempty subset of the given paths.
+	 * In practice that seems like overkill, given the crude nature of the
+	 * estimates, not to mention the possible effects of higher-level AND and
+	 * OR clauses.  Moreover, it's completely impractical if there are a large
+	 * number of paths, since the work would grow as O(2^N).
+	 *
+	 * As a heuristic, we first check for paths using exactly the same sets of
+	 * WHERE clauses + index predicate conditions, and reject all but the
+	 * cheapest-to-scan in any such group.  This primarily gets rid of indexes
+	 * that include the interesting columns but also irrelevant columns.  (In
+	 * situations where the DBA has gone overboard on creating variant
+	 * indexes, this can make for a very large reduction in the number of
+	 * paths considered further.)
+	 *
+	 * We then sort the surviving paths with the cheapest-to-scan first, and
+	 * for each path, consider using that path alone as the basis for a bitmap
+	 * scan.  Then we consider bitmap AND scans formed from that path plus
+	 * each subsequent (higher-cost) path, adding on a subsequent path if it
+	 * results in a reduction in the estimated total scan cost. This means we
+	 * consider about O(N^2) rather than O(2^N) path combinations, which is
+	 * quite tolerable, especially given than N is usually reasonably small
+	 * because of the prefiltering step.  The cheapest of these is returned.
+	 *
+	 * We will only consider AND combinations in which no two indexes use the
+	 * same WHERE clause.  This is a bit of a kluge: it's needed because
+	 * costsize.c and clausesel.c aren't very smart about redundant clauses.
+	 * They will usually double-count the redundant clauses, producing a
+	 * too-small selectivity that makes a redundant AND step look like it
+	 * reduces the total cost.  Perhaps someday that code will be smarter and
+	 * we can remove this limitation.  (But note that this also defends
+	 * against flat-out duplicate input paths, which can happen because
+	 * match_join_clauses_to_index will find the same OR join clauses that
+	 * extract_restriction_or_clauses has pulled OR restriction clauses out
+	 * of.)
+	 *
+	 * For the same reason, we reject AND combinations in which an index
+	 * predicate clause duplicates another clause.  Here we find it necessary
+	 * to be even stricter: we'll reject a partial index if any of its
+	 * predicate clauses are implied by the set of WHERE clauses and predicate
+	 * clauses used so far.  This covers cases such as a condition "x = 42"
+	 * used with a plain index, followed by a clauseless scan of a partial
+	 * index "WHERE x >= 40 AND x < 50".  The partial index has been accepted
+	 * only because "x = 42" was present, and so allowing it would partially
+	 * double-count selectivity.  (We could use predicate_implied_by on
+	 * regular qual clauses too, to have a more intelligent, but much more
+	 * expensive, check for redundancy --- but in most cases simple equality
+	 * seems to suffice.)
+	 */
+
+	/*
+	 * Extract clause usage info and detect any paths that use exactly the
+	 * same set of clauses; keep only the cheapest-to-scan of any such groups.
+	 * The surviving paths are put into an array for qsort'ing.
+	 */
+	pathinfoarray = (PathClauseUsage **)
+		palloc(npaths * sizeof(PathClauseUsage *));
+	clauselist = NIL;
+	npaths = 0;
+	foreach(l, paths)
+	{
+		Path	   *ipath = (Path *) lfirst(l);
+
+		pathinfo = classify_index_clause_usage(ipath, &clauselist);
+
+		/* If it's unclassifiable, treat it as distinct from all others */
+		if (pathinfo->unclassifiable)
+		{
+			pathinfoarray[npaths++] = pathinfo;
+			continue;
+		}
+
+		for (i = 0; i < npaths; i++)
+		{
+			if (!pathinfoarray[i]->unclassifiable &&
+				bms_equal(pathinfo->clauseids, pathinfoarray[i]->clauseids))
+				break;
+		}
+		if (i < npaths)
+		{
+			/* duplicate clauseids, keep the cheaper one */
+			Cost		ncost;
+			Cost		ocost;
+			Selectivity nselec;
+			Selectivity oselec;
+
+			cost_bitmap_tree_node(pathinfo->path, &ncost, &nselec);
+			cost_bitmap_tree_node(pathinfoarray[i]->path, &ocost, &oselec);
+			if (ncost < ocost)
+				pathinfoarray[i] = pathinfo;
+		}
+		else
+		{
+			/* not duplicate clauseids, add to array */
+			pathinfoarray[npaths++] = pathinfo;
+		}
+	}
+
+	/* If only one surviving path, we're done */
+	if (npaths == 1)
+		return pathinfoarray[0]->path;
+
+	/* Sort the surviving paths by index access cost */
+	qsort(pathinfoarray, npaths, sizeof(PathClauseUsage *),
+		  path_usage_comparator);
+
+	/*
+	 * For each surviving index, consider it as an "AND group leader", and see
+	 * whether adding on any of the later indexes results in an AND path with
+	 * cheaper total cost than before.  Then take the cheapest AND group.
+	 *
+	 * Note: paths that are either clauseless or unclassifiable will have
+	 * empty clauseids, so that they will not be rejected by the clauseids
+	 * filter here, nor will they cause later paths to be rejected by it.
+	 */
+	for (i = 0; i < npaths; i++)
+	{
+		Cost		costsofar;
+		List	   *qualsofar;
+		Bitmapset  *clauseidsofar;
+
+		pathinfo = pathinfoarray[i];
+		paths = list_make1(pathinfo->path);
+		costsofar = bitmap_scan_cost_est(root, rel, pathinfo->path);
+		qualsofar = list_concat_copy(pathinfo->quals, pathinfo->preds);
+		clauseidsofar = bms_copy(pathinfo->clauseids);
+
+		for (j = i + 1; j < npaths; j++)
+		{
+			Cost		newcost;
+
+			pathinfo = pathinfoarray[j];
+			/* Check for redundancy */
+			if (bms_overlap(pathinfo->clauseids, clauseidsofar))
+				continue;		/* consider it redundant */
+			if (pathinfo->preds)
+			{
+				bool		redundant = false;
+
+				/* we check each predicate clause separately */
+				foreach(l, pathinfo->preds)
+				{
+					Node	   *np = (Node *) lfirst(l);
+
+					if (predicate_implied_by(list_make1(np), qualsofar, false))
+					{
+						redundant = true;
+						break;	/* out of inner foreach loop */
+					}
+				}
+				if (redundant)
+					continue;
+			}
+			/* tentatively add new path to paths, so we can estimate cost */
+			paths = lappend(paths, pathinfo->path);
+			newcost = bitmap_and_cost_est(root, rel, paths);
+			if (newcost < costsofar)
+			{
+				/* keep new path in paths, update subsidiary variables */
+				costsofar = newcost;
+				qualsofar = list_concat(qualsofar, pathinfo->quals);
+				qualsofar = list_concat(qualsofar, pathinfo->preds);
+				clauseidsofar = bms_add_members(clauseidsofar,
+												pathinfo->clauseids);
+			}
+			else
+			{
+				/* reject new path, remove it from paths list */
+				paths = list_truncate(paths, list_length(paths) - 1);
+			}
+		}
+
+		/* Keep the cheapest AND-group (or singleton) */
+		if (i == 0 || costsofar < bestcost)
+		{
+			bestpaths = paths;
+			bestcost = costsofar;
+		}
+
+		/* some easy cleanup (we don't try real hard though) */
+		list_free(qualsofar);
+	}
+
+	if (list_length(bestpaths) == 1)
+		return (Path *) linitial(bestpaths);	/* no need for AND */
+	return (Path *) create_bitmap_and_path(root, rel, bestpaths);
+}
+
+/* qsort comparator to sort in increasing index access cost order */
+static int
+path_usage_comparator(const void *a, const void *b)
+{
+	PathClauseUsage *pa = *(PathClauseUsage *const *) a;
+	PathClauseUsage *pb = *(PathClauseUsage *const *) b;
+	Cost		acost;
+	Cost		bcost;
+	Selectivity aselec;
+	Selectivity bselec;
+
+	cost_bitmap_tree_node(pa->path, &acost, &aselec);
+	cost_bitmap_tree_node(pb->path, &bcost, &bselec);
+
+	/*
+	 * If costs are the same, sort by selectivity.
+	 */
+	if (acost < bcost)
+		return -1;
+	if (acost > bcost)
+		return 1;
+
+	if (aselec < bselec)
+		return -1;
+	if (aselec > bselec)
+		return 1;
+
+	return 0;
+}
+
+/*
+ * Estimate the cost of actually executing a bitmap scan with a single
+ * index path (which could be a BitmapAnd or BitmapOr node).
+ */
+static Cost
+bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath)
+{
+	BitmapHeapPath bpath;
+
+	/* Set up a dummy BitmapHeapPath */
+	bpath.path.type = T_BitmapHeapPath;
+	bpath.path.pathtype = T_BitmapHeapScan;
+	bpath.path.parent = rel;
+	bpath.path.pathtarget = rel->reltarget;
+	bpath.path.param_info = ipath->param_info;
+	bpath.path.pathkeys = NIL;
+	bpath.bitmapqual = ipath;
+
+	/*
+	 * Check the cost of temporary path without considering parallelism.
+	 * Parallel bitmap heap path will be considered at later stage.
+	 */
+	bpath.path.parallel_workers = 0;
+
+	/* Now we can do cost_bitmap_heap_scan */
+	cost_bitmap_heap_scan(&bpath.path, root, rel,
+						  bpath.path.param_info,
+						  ipath,
+						  get_loop_count(root, rel->relid,
+										 PATH_REQ_OUTER(ipath)));
+
+	return bpath.path.total_cost;
+}
+
+/*
+ * Estimate the cost of actually executing a BitmapAnd scan with the given
+ * inputs.
+ */
+static Cost
+bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths)
+{
+	BitmapAndPath *apath;
+
+	/*
+	 * Might as well build a real BitmapAndPath here, as the work is slightly
+	 * too complicated to be worth repeating just to save one palloc.
+	 */
+	apath = create_bitmap_and_path(root, rel, paths);
+
+	return bitmap_scan_cost_est(root, rel, (Path *) apath);
+}
+
+
+/*
+ * classify_index_clause_usage
+ *		Construct a PathClauseUsage struct describing the WHERE clauses and
+ *		index predicate clauses used by the given indexscan path.
+ *		We consider two clauses the same if they are equal().
+ *
+ * At some point we might want to migrate this info into the Path data
+ * structure proper, but for the moment it's only needed within
+ * choose_bitmap_and().
+ *
+ * *clauselist is used and expanded as needed to identify all the distinct
+ * clauses seen across successive calls.  Caller must initialize it to NIL
+ * before first call of a set.
+ */
+static PathClauseUsage *
+classify_index_clause_usage(Path *path, List **clauselist)
+{
+	PathClauseUsage *result;
+	Bitmapset  *clauseids;
+	ListCell   *lc;
+
+	result = (PathClauseUsage *) palloc(sizeof(PathClauseUsage));
+	result->path = path;
+
+	/* Recursively find the quals and preds used by the path */
+	result->quals = NIL;
+	result->preds = NIL;
+	find_indexpath_quals(path, &result->quals, &result->preds);
+
+	/*
+	 * Some machine-generated queries have outlandish numbers of qual clauses.
+	 * To avoid getting into O(N^2) behavior even in this preliminary
+	 * classification step, we want to limit the number of entries we can
+	 * accumulate in *clauselist.  Treat any path with more than 100 quals +
+	 * preds as unclassifiable, which will cause calling code to consider it
+	 * distinct from all other paths.
+	 */
+	if (list_length(result->quals) + list_length(result->preds) > 100)
+	{
+		result->clauseids = NULL;
+		result->unclassifiable = true;
+		return result;
+	}
+
+	/* Build up a bitmapset representing the quals and preds */
+	clauseids = NULL;
+	foreach(lc, result->quals)
+	{
+		Node	   *node = (Node *) lfirst(lc);
+
+		clauseids = bms_add_member(clauseids,
+								   find_list_position(node, clauselist));
+	}
+	foreach(lc, result->preds)
+	{
+		Node	   *node = (Node *) lfirst(lc);
+
+		clauseids = bms_add_member(clauseids,
+								   find_list_position(node, clauselist));
+	}
+	result->clauseids = clauseids;
+	result->unclassifiable = false;
+
+	return result;
+}
+
+
+/*
+ * find_indexpath_quals
+ *
+ * Given the Path structure for a plain or bitmap indexscan, extract lists
+ * of all the index clauses and index predicate conditions used in the Path.
+ * These are appended to the initial contents of *quals and *preds (hence
+ * caller should initialize those to NIL).
+ *
+ * Note we are not trying to produce an accurate representation of the AND/OR
+ * semantics of the Path, but just find out all the base conditions used.
+ *
+ * The result lists contain pointers to the expressions used in the Path,
+ * but all the list cells are freshly built, so it's safe to destructively
+ * modify the lists (eg, by concat'ing with other lists).
+ */
+static void
+find_indexpath_quals(Path *bitmapqual, List **quals, List **preds)
+{
+	if (IsA(bitmapqual, BitmapAndPath))
+	{
+		BitmapAndPath *apath = (BitmapAndPath *) bitmapqual;
+		ListCell   *l;
+
+		foreach(l, apath->bitmapquals)
+		{
+			find_indexpath_quals((Path *) lfirst(l), quals, preds);
+		}
+	}
+	else if (IsA(bitmapqual, BitmapOrPath))
+	{
+		BitmapOrPath *opath = (BitmapOrPath *) bitmapqual;
+		ListCell   *l;
+
+		foreach(l, opath->bitmapquals)
+		{
+			find_indexpath_quals((Path *) lfirst(l), quals, preds);
+		}
+	}
+	else if (IsA(bitmapqual, IndexPath))
+	{
+		IndexPath  *ipath = (IndexPath *) bitmapqual;
+		ListCell   *l;
+
+		foreach(l, ipath->indexclauses)
+		{
+			IndexClause *iclause = (IndexClause *) lfirst(l);
+
+			*quals = lappend(*quals, iclause->rinfo->clause);
+		}
+		*preds = list_concat(*preds, ipath->indexinfo->indpred);
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d", nodeTag(bitmapqual));
+}
+
+
+/*
+ * find_list_position
+ *		Return the given node's position (counting from 0) in the given
+ *		list of nodes.  If it's not equal() to any existing list member,
+ *		add it at the end, and return that position.
+ */
+static int
+find_list_position(Node *node, List **nodelist)
+{
+	int			i;
+	ListCell   *lc;
+
+	i = 0;
+	foreach(lc, *nodelist)
+	{
+		Node	   *oldnode = (Node *) lfirst(lc);
+
+		if (equal(node, oldnode))
+			return i;
+		i++;
+	}
+
+	*nodelist = lappend(*nodelist, node);
+
+	return i;
+}
+
+
+/*
+ * check_index_only
+ *		Determine whether an index-only scan is possible for this index.
+ */
+static bool
+check_index_only(RelOptInfo *rel, IndexOptInfo *index)
+{
+	bool		result;
+	Bitmapset  *attrs_used = NULL;
+	Bitmapset  *index_canreturn_attrs = NULL;
+	ListCell   *lc;
+	int			i;
+
+	/* Index-only scans must be enabled */
+	if (!enable_indexonlyscan)
+		return false;
+
+	/*
+	 * Check that all needed attributes of the relation are available from the
+	 * index.
+	 */
+
+	/*
+	 * First, identify all the attributes needed for joins or final output.
+	 * Note: we must look at rel's targetlist, not the attr_needed data,
+	 * because attr_needed isn't computed for inheritance child rels.
+	 */
+	pull_varattnos((Node *) rel->reltarget->exprs, rel->relid, &attrs_used);
+
+	/*
+	 * Add all the attributes used by restriction clauses; but consider only
+	 * those clauses not implied by the index predicate, since ones that are
+	 * so implied don't need to be checked explicitly in the plan.
+	 *
+	 * Note: attributes used only in index quals would not be needed at
+	 * runtime either, if we are certain that the index is not lossy.  However
+	 * it'd be complicated to account for that accurately, and it doesn't
+	 * matter in most cases, since we'd conclude that such attributes are
+	 * available from the index anyway.
+	 */
+	foreach(lc, index->indrestrictinfo)
+	{
+		RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+
+		pull_varattnos((Node *) rinfo->clause, rel->relid, &attrs_used);
+	}
+
+	/*
+	 * Construct a bitmapset of columns that the index can return back in an
+	 * index-only scan.
+	 */
+	for (i = 0; i < index->ncolumns; i++)
+	{
+		int			attno = index->indexkeys[i];
+
+		/*
+		 * For the moment, we just ignore index expressions.  It might be nice
+		 * to do something with them, later.
+		 */
+		if (attno == 0)
+			continue;
+
+		if (index->canreturn[i])
+			index_canreturn_attrs =
+				bms_add_member(index_canreturn_attrs,
+							   attno - FirstLowInvalidHeapAttributeNumber);
+	}
+
+	/* Do we have all the necessary attributes? */
+	result = bms_is_subset(attrs_used, index_canreturn_attrs);
+
+	bms_free(attrs_used);
+	bms_free(index_canreturn_attrs);
+
+	return result;
+}
+
+/*
+ * get_loop_count
+ *		Choose the loop count estimate to use for costing a parameterized path
+ *		with the given set of outer relids.
+ *
+ * Since we produce parameterized paths before we've begun to generate join
+ * relations, it's impossible to predict exactly how many times a parameterized
+ * path will be iterated; we don't know the size of the relation that will be
+ * on the outside of the nestloop.  However, we should try to account for
+ * multiple iterations somehow in costing the path.  The heuristic embodied
+ * here is to use the rowcount of the smallest other base relation needed in
+ * the join clauses used by the path.  (We could alternatively consider the
+ * largest one, but that seems too optimistic.)  This is of course the right
+ * answer for single-other-relation cases, and it seems like a reasonable
+ * zero-order approximation for multiway-join cases.
+ *
+ * In addition, we check to see if the other side of each join clause is on
+ * the inside of some semijoin that the current relation is on the outside of.
+ * If so, the only way that a parameterized path could be used is if the
+ * semijoin RHS has been unique-ified, so we should use the number of unique
+ * RHS rows rather than using the relation's raw rowcount.
+ *
+ * Note: for this to work, allpaths.c must establish all baserel size
+ * estimates before it begins to compute paths, or at least before it
+ * calls create_index_paths().
+ */
+static double
+get_loop_count(PlannerInfo *root, Index cur_relid, Relids outer_relids)
+{
+	double		result;
+	int			outer_relid;
+
+	/* For a non-parameterized path, just return 1.0 quickly */
+	if (outer_relids == NULL)
+		return 1.0;
+
+	result = 0.0;
+	outer_relid = -1;
+	while ((outer_relid = bms_next_member(outer_relids, outer_relid)) >= 0)
+	{
+		RelOptInfo *outer_rel;
+		double		rowcount;
+
+		/* Paranoia: ignore bogus relid indexes */
+		if (outer_relid >= root->simple_rel_array_size)
+			continue;
+		outer_rel = root->simple_rel_array[outer_relid];
+		if (outer_rel == NULL)
+			continue;
+		Assert(outer_rel->relid == outer_relid);	/* sanity check on array */
+
+		/* Other relation could be proven empty, if so ignore */
+		if (IS_DUMMY_REL(outer_rel))
+			continue;
+
+		/* Otherwise, rel's rows estimate should be valid by now */
+		Assert(outer_rel->rows > 0);
+
+		/* Check to see if rel is on the inside of any semijoins */
+		rowcount = adjust_rowcount_for_semijoins(root,
+												 cur_relid,
+												 outer_relid,
+												 outer_rel->rows);
+
+		/* Remember smallest row count estimate among the outer rels */
+		if (result == 0.0 || result > rowcount)
+			result = rowcount;
+	}
+	/* Return 1.0 if we found no valid relations (shouldn't happen) */
+	return (result > 0.0) ? result : 1.0;
+}
+
+/*
+ * Check to see if outer_relid is on the inside of any semijoin that cur_relid
+ * is on the outside of.  If so, replace rowcount with the estimated number of
+ * unique rows from the semijoin RHS (assuming that's smaller, which it might
+ * not be).  The estimate is crude but it's the best we can do at this stage
+ * of the proceedings.
+ */
+static double
+adjust_rowcount_for_semijoins(PlannerInfo *root,
+							  Index cur_relid,
+							  Index outer_relid,
+							  double rowcount)
+{
+	ListCell   *lc;
+
+	foreach(lc, root->join_info_list)
+	{
+		SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
+
+		if (sjinfo->jointype == JOIN_SEMI &&
+			bms_is_member(cur_relid, sjinfo->syn_lefthand) &&
+			bms_is_member(outer_relid, sjinfo->syn_righthand))
+		{
+			/* Estimate number of unique-ified rows */
+			double		nraw;
+			double		nunique;
+
+			nraw = approximate_joinrel_size(root, sjinfo->syn_righthand);
+			nunique = estimate_num_groups(root,
+										  sjinfo->semi_rhs_exprs,
+										  nraw,
+										  NULL,
+										  NULL);
+			if (rowcount > nunique)
+				rowcount = nunique;
+		}
+	}
+	return rowcount;
+}
+
+/*
+ * Make an approximate estimate of the size of a joinrel.
+ *
+ * We don't have enough info at this point to get a good estimate, so we
+ * just multiply the base relation sizes together.  Fortunately, this is
+ * the right answer anyway for the most common case with a single relation
+ * on the RHS of a semijoin.  Also, estimate_num_groups() has only a weak
+ * dependency on its input_rows argument (it basically uses it as a clamp).
+ * So we might be able to get a fairly decent end result even with a severe
+ * overestimate of the RHS's raw size.
+ */
+static double
+approximate_joinrel_size(PlannerInfo *root, Relids relids)
+{
+	double		rowcount = 1.0;
+	int			relid;
+
+	relid = -1;
+	while ((relid = bms_next_member(relids, relid)) >= 0)
+	{
+		RelOptInfo *rel;
+
+		/* Paranoia: ignore bogus relid indexes */
+		if (relid >= root->simple_rel_array_size)
+			continue;
+		rel = root->simple_rel_array[relid];
+		if (rel == NULL)
+			continue;
+		Assert(rel->relid == relid);	/* sanity check on array */
+
+		/* Relation could be proven empty, if so ignore */
+		if (IS_DUMMY_REL(rel))
+			continue;
+
+		/* Otherwise, rel's rows estimate should be valid by now */
+		Assert(rel->rows > 0);
+
+		/* Accumulate product */
+		rowcount *= rel->rows;
+	}
+	return rowcount;
+}
+
+
+/****************************************************************************
+ *				----  ROUTINES TO CHECK QUERY CLAUSES  ----
+ ****************************************************************************/
+
+/*
+ * match_restriction_clauses_to_index
+ *	  Identify restriction clauses for the rel that match the index.
+ *	  Matching clauses are added to *clauseset.
+ */
+static void
+match_restriction_clauses_to_index(PlannerInfo *root,
+								   IndexOptInfo *index,
+								   IndexClauseSet *clauseset)
+{
+	/* We can ignore clauses that are implied by the index predicate */
+	match_clauses_to_index(root, index->indrestrictinfo, index, clauseset);
+}
+
+/*
+ * match_join_clauses_to_index
+ *	  Identify join clauses for the rel that match the index.
+ *	  Matching clauses are added to *clauseset.
+ *	  Also, add any potentially usable join OR clauses to *joinorclauses.
+ */
+static void
+match_join_clauses_to_index(PlannerInfo *root,
+							RelOptInfo *rel, IndexOptInfo *index,
+							IndexClauseSet *clauseset,
+							List **joinorclauses)
+{
+	ListCell   *lc;
+
+	/* Scan the rel's join clauses */
+	foreach(lc, rel->joininfo)
+	{
+		RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+
+		/* Check if clause can be moved to this rel */
+		if (!join_clause_is_movable_to(rinfo, rel))
+			continue;
+
+		/* Potentially usable, so see if it matches the index or is an OR */
+		if (restriction_is_or_clause(rinfo))
+			*joinorclauses = lappend(*joinorclauses, rinfo);
+		else
+			match_clause_to_index(root, rinfo, index, clauseset);
+	}
+}
+
+/*
+ * match_eclass_clauses_to_index
+ *	  Identify EquivalenceClass join clauses for the rel that match the index.
+ *	  Matching clauses are added to *clauseset.
+ */
+static void
+match_eclass_clauses_to_index(PlannerInfo *root, IndexOptInfo *index,
+							  IndexClauseSet *clauseset)
+{
+	int			indexcol;
+
+	/* No work if rel is not in any such ECs */
+	if (!index->rel->has_eclass_joins)
+		return;
+
+	for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
+	{
+		ec_member_matches_arg arg;
+		List	   *clauses;
+
+		/* Generate clauses, skipping any that join to lateral_referencers */
+		arg.index = index;
+		arg.indexcol = indexcol;
+		clauses = generate_implied_equalities_for_column(root,
+														 index->rel,
+														 ec_member_matches_indexcol,
+														 (void *) &arg,
+														 index->rel->lateral_referencers);
+
+		/*
+		 * We have to check whether the results actually do match the index,
+		 * since for non-btree indexes the EC's equality operators might not
+		 * be in the index opclass (cf ec_member_matches_indexcol).
+		 */
+		match_clauses_to_index(root, clauses, index, clauseset);
+	}
+}
+
+/*
+ * match_clauses_to_index
+ *	  Perform match_clause_to_index() for each clause in a list.
+ *	  Matching clauses are added to *clauseset.
+ */
+static void
+match_clauses_to_index(PlannerInfo *root,
+					   List *clauses,
+					   IndexOptInfo *index,
+					   IndexClauseSet *clauseset)
+{
+	ListCell   *lc;
+
+	foreach(lc, clauses)
+	{
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
+
+		match_clause_to_index(root, rinfo, index, clauseset);
+	}
+}
+
+/*
+ * match_clause_to_index
+ *	  Test whether a qual clause can be used with an index.
+ *
+ * If the clause is usable, add an IndexClause entry for it to the appropriate
+ * list in *clauseset.  (*clauseset must be initialized to zeroes before first
+ * call.)
+ *
+ * Note: in some circumstances we may find the same RestrictInfos coming from
+ * multiple places.  Defend against redundant outputs by refusing to add a
+ * clause twice (pointer equality should be a good enough check for this).
+ *
+ * Note: it's possible that a badly-defined index could have multiple matching
+ * columns.  We always select the first match if so; this avoids scenarios
+ * wherein we get an inflated idea of the index's selectivity by using the
+ * same clause multiple times with different index columns.
+ */
+static void
+match_clause_to_index(PlannerInfo *root,
+					  RestrictInfo *rinfo,
+					  IndexOptInfo *index,
+					  IndexClauseSet *clauseset)
+{
+	int			indexcol;
+
+	/*
+	 * Never match pseudoconstants to indexes.  (Normally a match could not
+	 * happen anyway, since a pseudoconstant clause couldn't contain a Var,
+	 * but what if someone builds an expression index on a constant? It's not
+	 * totally unreasonable to do so with a partial index, either.)
+	 */
+	if (rinfo->pseudoconstant)
+		return;
+
+	/*
+	 * If clause can't be used as an indexqual because it must wait till after
+	 * some lower-security-level restriction clause, reject it.
+	 */
+	if (!restriction_is_securely_promotable(rinfo, index->rel))
+		return;
+
+	/* OK, check each index key column for a match */
+	for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
+	{
+		IndexClause *iclause;
+		ListCell   *lc;
+
+		/* Ignore duplicates */
+		foreach(lc, clauseset->indexclauses[indexcol])
+		{
+			IndexClause *iclause = (IndexClause *) lfirst(lc);
+
+			if (iclause->rinfo == rinfo)
+				return;
+		}
+
+		/* OK, try to match the clause to the index column */
+		iclause = match_clause_to_indexcol(root,
+										   rinfo,
+										   indexcol,
+										   index);
+		if (iclause)
+		{
+			/* Success, so record it */
+			clauseset->indexclauses[indexcol] =
+				lappend(clauseset->indexclauses[indexcol], iclause);
+			clauseset->nonempty = true;
+			return;
+		}
+	}
+}
+
+/*
+ * match_clause_to_indexcol()
+ *	  Determine whether a restriction clause matches a column of an index,
+ *	  and if so, build an IndexClause node describing the details.
+ *
+ *	  To match an index normally, an operator clause:
+ *
+ *	  (1)  must be in the form (indexkey op const) or (const op indexkey);
+ *		   and
+ *	  (2)  must contain an operator which is in the index's operator family
+ *		   for this column; and
+ *	  (3)  must match the collation of the index, if collation is relevant.
+ *
+ *	  Our definition of "const" is exceedingly liberal: we allow anything that
+ *	  doesn't involve a volatile function or a Var of the index's relation.
+ *	  In particular, Vars belonging to other relations of the query are
+ *	  accepted here, since a clause of that form can be used in a
+ *	  parameterized indexscan.  It's the responsibility of higher code levels
+ *	  to manage restriction and join clauses appropriately.
+ *
+ *	  Note: we do need to check for Vars of the index's relation on the
+ *	  "const" side of the clause, since clauses like (a.f1 OP (b.f2 OP a.f3))
+ *	  are not processable by a parameterized indexscan on a.f1, whereas
+ *	  something like (a.f1 OP (b.f2 OP c.f3)) is.
+ *
+ *	  Presently, the executor can only deal with indexquals that have the
+ *	  indexkey on the left, so we can only use clauses that have the indexkey
+ *	  on the right if we can commute the clause to put the key on the left.
+ *	  We handle that by generating an IndexClause with the correctly-commuted
+ *	  opclause as a derived indexqual.
+ *
+ *	  If the index has a collation, the clause must have the same collation.
+ *	  For collation-less indexes, we assume it doesn't matter; this is
+ *	  necessary for cases like "hstore ? text", wherein hstore's operators
+ *	  don't care about collation but the clause will get marked with a
+ *	  collation anyway because of the text argument.  (This logic is
+ *	  embodied in the macro IndexCollMatchesExprColl.)
+ *
+ *	  It is also possible to match RowCompareExpr clauses to indexes (but
+ *	  currently, only btree indexes handle this).
+ *
+ *	  It is also possible to match ScalarArrayOpExpr clauses to indexes, when
+ *	  the clause is of the form "indexkey op ANY (arrayconst)".
+ *
+ *	  For boolean indexes, it is also possible to match the clause directly
+ *	  to the indexkey; or perhaps the clause is (NOT indexkey).
+ *
+ *	  And, last but not least, some operators and functions can be processed
+ *	  to derive (typically lossy) indexquals from a clause that isn't in
+ *	  itself indexable.  If we see that any operand of an OpExpr or FuncExpr
+ *	  matches the index key, and the function has a planner support function
+ *	  attached to it, we'll invoke the support function to see if such an
+ *	  indexqual can be built.
+ *
+ * 'rinfo' is the clause to be tested (as a RestrictInfo node).
+ * 'indexcol' is a column number of 'index' (counting from 0).
+ * 'index' is the index of interest.
+ *
+ * Returns an IndexClause if the clause can be used with this index key,
+ * or NULL if not.
+ *
+ * NOTE:  returns NULL if clause is an OR or AND clause; it is the
+ * responsibility of higher-level routines to cope with those.
+ */
+static IndexClause *
+match_clause_to_indexcol(PlannerInfo *root,
+						 RestrictInfo *rinfo,
+						 int indexcol,
+						 IndexOptInfo *index)
+{
+	IndexClause *iclause;
+	Expr	   *clause = rinfo->clause;
+	Oid			opfamily;
+
+	Assert(indexcol < index->nkeycolumns);
+
+	/*
+	 * Historically this code has coped with NULL clauses.  That's probably
+	 * not possible anymore, but we might as well continue to cope.
+	 */
+	if (clause == NULL)
+		return NULL;
+
+	/* First check for boolean-index cases. */
+	opfamily = index->opfamily[indexcol];
+	if (IsBooleanOpfamily(opfamily))
+	{
+		iclause = match_boolean_index_clause(root, rinfo, indexcol, index);
+		if (iclause)
+			return iclause;
+	}
+
+	/*
+	 * Clause must be an opclause, funcclause, ScalarArrayOpExpr, or
+	 * RowCompareExpr.  Or, if the index supports it, we can handle IS
+	 * NULL/NOT NULL clauses.
+	 */
+	if (IsA(clause, OpExpr))
+	{
+		return match_opclause_to_indexcol(root, rinfo, indexcol, index);
+	}
+	else if (IsA(clause, FuncExpr))
+	{
+		return match_funcclause_to_indexcol(root, rinfo, indexcol, index);
+	}
+	else if (IsA(clause, ScalarArrayOpExpr))
+	{
+		return match_saopclause_to_indexcol(root, rinfo, indexcol, index);
+	}
+	else if (IsA(clause, RowCompareExpr))
+	{
+		return match_rowcompare_to_indexcol(root, rinfo, indexcol, index);
+	}
+	else if (index->amsearchnulls && IsA(clause, NullTest))
+	{
+		NullTest   *nt = (NullTest *) clause;
+
+		if (!nt->argisrow &&
+			match_index_to_operand((Node *) nt->arg, indexcol, index))
+		{
+			iclause = makeNode(IndexClause);
+			iclause->rinfo = rinfo;
+			iclause->indexquals = list_make1(rinfo);
+			iclause->lossy = false;
+			iclause->indexcol = indexcol;
+			iclause->indexcols = NIL;
+			return iclause;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * match_boolean_index_clause
+ *	  Recognize restriction clauses that can be matched to a boolean index.
+ *
+ * The idea here is that, for an index on a boolean column that supports the
+ * BooleanEqualOperator, we can transform a plain reference to the indexkey
+ * into "indexkey = true", or "NOT indexkey" into "indexkey = false", etc,
+ * so as to make the expression indexable using the index's "=" operator.
+ * Since Postgres 8.1, we must do this because constant simplification does
+ * the reverse transformation; without this code there'd be no way to use
+ * such an index at all.
+ *
+ * This should be called only when IsBooleanOpfamily() recognizes the
+ * index's operator family.  We check to see if the clause matches the
+ * index's key, and if so, build a suitable IndexClause.
+ */
+static IndexClause *
+match_boolean_index_clause(PlannerInfo *root,
+						   RestrictInfo *rinfo,
+						   int indexcol,
+						   IndexOptInfo *index)
+{
+	Node	   *clause = (Node *) rinfo->clause;
+	Expr	   *op = NULL;
+
+	/* Direct match? */
+	if (match_index_to_operand(clause, indexcol, index))
+	{
+		/* convert to indexkey = TRUE */
+		op = make_opclause(BooleanEqualOperator, BOOLOID, false,
+						   (Expr *) clause,
+						   (Expr *) makeBoolConst(true, false),
+						   InvalidOid, InvalidOid);
+	}
+	/* NOT clause? */
+	else if (is_notclause(clause))
+	{
+		Node	   *arg = (Node *) get_notclausearg((Expr *) clause);
+
+		if (match_index_to_operand(arg, indexcol, index))
+		{
+			/* convert to indexkey = FALSE */
+			op = make_opclause(BooleanEqualOperator, BOOLOID, false,
+							   (Expr *) arg,
+							   (Expr *) makeBoolConst(false, false),
+							   InvalidOid, InvalidOid);
+		}
+	}
+
+	/*
+	 * Since we only consider clauses at top level of WHERE, we can convert
+	 * indexkey IS TRUE and indexkey IS FALSE to index searches as well.  The
+	 * different meaning for NULL isn't important.
+	 */
+	else if (clause && IsA(clause, BooleanTest))
+	{
+		BooleanTest *btest = (BooleanTest *) clause;
+		Node	   *arg = (Node *) btest->arg;
+
+		if (btest->booltesttype == IS_TRUE &&
+			match_index_to_operand(arg, indexcol, index))
+		{
+			/* convert to indexkey = TRUE */
+			op = make_opclause(BooleanEqualOperator, BOOLOID, false,
+							   (Expr *) arg,
+							   (Expr *) makeBoolConst(true, false),
+							   InvalidOid, InvalidOid);
+		}
+		else if (btest->booltesttype == IS_FALSE &&
+				 match_index_to_operand(arg, indexcol, index))
+		{
+			/* convert to indexkey = FALSE */
+			op = make_opclause(BooleanEqualOperator, BOOLOID, false,
+							   (Expr *) arg,
+							   (Expr *) makeBoolConst(false, false),
+							   InvalidOid, InvalidOid);
+		}
+	}
+
+	/*
+	 * If we successfully made an operator clause from the given qual, we must
+	 * wrap it in an IndexClause.  It's not lossy.
+	 */
+	if (op)
+	{
+		IndexClause *iclause = makeNode(IndexClause);
+
+		iclause->rinfo = rinfo;
+		iclause->indexquals = list_make1(make_simple_restrictinfo(root, op));
+		iclause->lossy = false;
+		iclause->indexcol = indexcol;
+		iclause->indexcols = NIL;
+		return iclause;
+	}
+
+	return NULL;
+}
+
+/*
+ * match_opclause_to_indexcol()
+ *	  Handles the OpExpr case for match_clause_to_indexcol(),
+ *	  which see for comments.
+ */
+static IndexClause *
+match_opclause_to_indexcol(PlannerInfo *root,
+						   RestrictInfo *rinfo,
+						   int indexcol,
+						   IndexOptInfo *index)
+{
+	IndexClause *iclause;
+	OpExpr	   *clause = (OpExpr *) rinfo->clause;
+	Node	   *leftop,
+			   *rightop;
+	Oid			expr_op;
+	Oid			expr_coll;
+	Index		index_relid;
+	Oid			opfamily;
+	Oid			idxcollation;
+
+	/*
+	 * Only binary operators need apply.  (In theory, a planner support
+	 * function could do something with a unary operator, but it seems
+	 * unlikely to be worth the cycles to check.)
+	 */
+	if (list_length(clause->args) != 2)
+		return NULL;
+
+	leftop = (Node *) linitial(clause->args);
+	rightop = (Node *) lsecond(clause->args);
+	expr_op = clause->opno;
+	expr_coll = clause->inputcollid;
+
+	index_relid = index->rel->relid;
+	opfamily = index->opfamily[indexcol];
+	idxcollation = index->indexcollations[indexcol];
+
+	/*
+	 * Check for clauses of the form: (indexkey operator constant) or
+	 * (constant operator indexkey).  See match_clause_to_indexcol's notes
+	 * about const-ness.
+	 *
+	 * Note that we don't ask the support function about clauses that don't
+	 * have one of these forms.  Again, in principle it might be possible to
+	 * do something, but it seems unlikely to be worth the cycles to check.
+	 */
+	if (match_index_to_operand(leftop, indexcol, index) &&
+		!bms_is_member(index_relid, rinfo->right_relids) &&
+		!contain_volatile_functions(rightop))
+	{
+		if (IndexCollMatchesExprColl(idxcollation, expr_coll) &&
+			op_in_opfamily(expr_op, opfamily))
+		{
+			iclause = makeNode(IndexClause);
+			iclause->rinfo = rinfo;
+			iclause->indexquals = list_make1(rinfo);
+			iclause->lossy = false;
+			iclause->indexcol = indexcol;
+			iclause->indexcols = NIL;
+			return iclause;
+		}
+
+		/*
+		 * If we didn't find a member of the index's opfamily, try the support
+		 * function for the operator's underlying function.
+		 */
+		set_opfuncid(clause);	/* make sure we have opfuncid */
+		return get_index_clause_from_support(root,
+											 rinfo,
+											 clause->opfuncid,
+											 0, /* indexarg on left */
+											 indexcol,
+											 index);
+	}
+
+	if (match_index_to_operand(rightop, indexcol, index) &&
+		!bms_is_member(index_relid, rinfo->left_relids) &&
+		!contain_volatile_functions(leftop))
+	{
+		if (IndexCollMatchesExprColl(idxcollation, expr_coll))
+		{
+			Oid			comm_op = get_commutator(expr_op);
+
+			if (OidIsValid(comm_op) &&
+				op_in_opfamily(comm_op, opfamily))
+			{
+				RestrictInfo *commrinfo;
+
+				/* Build a commuted OpExpr and RestrictInfo */
+				commrinfo = commute_restrictinfo(rinfo, comm_op);
+
+				/* Make an IndexClause showing that as a derived qual */
+				iclause = makeNode(IndexClause);
+				iclause->rinfo = rinfo;
+				iclause->indexquals = list_make1(commrinfo);
+				iclause->lossy = false;
+				iclause->indexcol = indexcol;
+				iclause->indexcols = NIL;
+				return iclause;
+			}
+		}
+
+		/*
+		 * If we didn't find a member of the index's opfamily, try the support
+		 * function for the operator's underlying function.
+		 */
+		set_opfuncid(clause);	/* make sure we have opfuncid */
+		return get_index_clause_from_support(root,
+											 rinfo,
+											 clause->opfuncid,
+											 1, /* indexarg on right */
+											 indexcol,
+											 index);
+	}
+
+	return NULL;
+}
+
+/*
+ * match_funcclause_to_indexcol()
+ *	  Handles the FuncExpr case for match_clause_to_indexcol(),
+ *	  which see for comments.
+ */
+static IndexClause *
+match_funcclause_to_indexcol(PlannerInfo *root,
+							 RestrictInfo *rinfo,
+							 int indexcol,
+							 IndexOptInfo *index)
+{
+	FuncExpr   *clause = (FuncExpr *) rinfo->clause;
+	int			indexarg;
+	ListCell   *lc;
+
+	/*
+	 * We have no built-in intelligence about function clauses, but if there's
+	 * a planner support function, it might be able to do something.  But, to
+	 * cut down on wasted planning cycles, only call the support function if
+	 * at least one argument matches the target index column.
+	 *
+	 * Note that we don't insist on the other arguments being pseudoconstants;
+	 * the support function has to check that.  This is to allow cases where
+	 * only some of the other arguments need to be included in the indexqual.
+	 */
+	indexarg = 0;
+	foreach(lc, clause->args)
+	{
+		Node	   *op = (Node *) lfirst(lc);
+
+		if (match_index_to_operand(op, indexcol, index))
+		{
+			return get_index_clause_from_support(root,
+												 rinfo,
+												 clause->funcid,
+												 indexarg,
+												 indexcol,
+												 index);
+		}
+
+		indexarg++;
+	}
+
+	return NULL;
+}
+
+/*
+ * get_index_clause_from_support()
+ *		If the function has a planner support function, try to construct
+ *		an IndexClause using indexquals created by the support function.
+ */
+static IndexClause *
+get_index_clause_from_support(PlannerInfo *root,
+							  RestrictInfo *rinfo,
+							  Oid funcid,
+							  int indexarg,
+							  int indexcol,
+							  IndexOptInfo *index)
+{
+	Oid			prosupport = get_func_support(funcid);
+	SupportRequestIndexCondition req;
+	List	   *sresult;
+
+	if (!OidIsValid(prosupport))
+		return NULL;
+
+	req.type = T_SupportRequestIndexCondition;
+	req.root = root;
+	req.funcid = funcid;
+	req.node = (Node *) rinfo->clause;
+	req.indexarg = indexarg;
+	req.index = index;
+	req.indexcol = indexcol;
+	req.opfamily = index->opfamily[indexcol];
+	req.indexcollation = index->indexcollations[indexcol];
+
+	req.lossy = true;			/* default assumption */
+
+	sresult = (List *)
+		DatumGetPointer(OidFunctionCall1(prosupport,
+										 PointerGetDatum(&req)));
+
+	if (sresult != NIL)
+	{
+		IndexClause *iclause = makeNode(IndexClause);
+		List	   *indexquals = NIL;
+		ListCell   *lc;
+
+		/*
+		 * The support function API says it should just give back bare
+		 * clauses, so here we must wrap each one in a RestrictInfo.
+		 */
+		foreach(lc, sresult)
+		{
+			Expr	   *clause = (Expr *) lfirst(lc);
+
+			indexquals = lappend(indexquals,
+								 make_simple_restrictinfo(root, clause));
+		}
+
+		iclause->rinfo = rinfo;
+		iclause->indexquals = indexquals;
+		iclause->lossy = req.lossy;
+		iclause->indexcol = indexcol;
+		iclause->indexcols = NIL;
+
+		return iclause;
+	}
+
+	return NULL;
+}
+
+/*
+ * match_saopclause_to_indexcol()
+ *	  Handles the ScalarArrayOpExpr case for match_clause_to_indexcol(),
+ *	  which see for comments.
+ */
+static IndexClause *
+match_saopclause_to_indexcol(PlannerInfo *root,
+							 RestrictInfo *rinfo,
+							 int indexcol,
+							 IndexOptInfo *index)
+{
+	ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) rinfo->clause;
+	Node	   *leftop,
+			   *rightop;
+	Relids		right_relids;
+	Oid			expr_op;
+	Oid			expr_coll;
+	Index		index_relid;
+	Oid			opfamily;
+	Oid			idxcollation;
+
+	/* We only accept ANY clauses, not ALL */
+	if (!saop->useOr)
+		return NULL;
+	leftop = (Node *) linitial(saop->args);
+	rightop = (Node *) lsecond(saop->args);
+	right_relids = pull_varnos(root, rightop);
+	expr_op = saop->opno;
+	expr_coll = saop->inputcollid;
+
+	index_relid = index->rel->relid;
+	opfamily = index->opfamily[indexcol];
+	idxcollation = index->indexcollations[indexcol];
+
+	/*
+	 * We must have indexkey on the left and a pseudo-constant array argument.
+	 */
+	if (match_index_to_operand(leftop, indexcol, index) &&
+		!bms_is_member(index_relid, right_relids) &&
+		!contain_volatile_functions(rightop))
+	{
+		if (IndexCollMatchesExprColl(idxcollation, expr_coll) &&
+			op_in_opfamily(expr_op, opfamily))
+		{
+			IndexClause *iclause = makeNode(IndexClause);
+
+			iclause->rinfo = rinfo;
+			iclause->indexquals = list_make1(rinfo);
+			iclause->lossy = false;
+			iclause->indexcol = indexcol;
+			iclause->indexcols = NIL;
+			return iclause;
+		}
+
+		/*
+		 * We do not currently ask support functions about ScalarArrayOpExprs,
+		 * though in principle we could.
+		 */
+	}
+
+	return NULL;
+}
+
+/*
+ * match_rowcompare_to_indexcol()
+ *	  Handles the RowCompareExpr case for match_clause_to_indexcol(),
+ *	  which see for comments.
+ *
+ * In this routine we check whether the first column of the row comparison
+ * matches the target index column.  This is sufficient to guarantee that some
+ * index condition can be constructed from the RowCompareExpr --- the rest
+ * is handled by expand_indexqual_rowcompare().
+ */
+static IndexClause *
+match_rowcompare_to_indexcol(PlannerInfo *root,
+							 RestrictInfo *rinfo,
+							 int indexcol,
+							 IndexOptInfo *index)
+{
+	RowCompareExpr *clause = (RowCompareExpr *) rinfo->clause;
+	Index		index_relid;
+	Oid			opfamily;
+	Oid			idxcollation;
+	Node	   *leftop,
+			   *rightop;
+	bool		var_on_left;
+	Oid			expr_op;
+	Oid			expr_coll;
+
+	/* Forget it if we're not dealing with a btree index */
+	if (index->relam != BTREE_AM_OID)
+		return NULL;
+
+	index_relid = index->rel->relid;
+	opfamily = index->opfamily[indexcol];
+	idxcollation = index->indexcollations[indexcol];
+
+	/*
+	 * We could do the matching on the basis of insisting that the opfamily
+	 * shown in the RowCompareExpr be the same as the index column's opfamily,
+	 * but that could fail in the presence of reverse-sort opfamilies: it'd be
+	 * a matter of chance whether RowCompareExpr had picked the forward or
+	 * reverse-sort family.  So look only at the operator, and match if it is
+	 * a member of the index's opfamily (after commutation, if the indexkey is
+	 * on the right).  We'll worry later about whether any additional
+	 * operators are matchable to the index.
+	 */
+	leftop = (Node *) linitial(clause->largs);
+	rightop = (Node *) linitial(clause->rargs);
+	expr_op = linitial_oid(clause->opnos);
+	expr_coll = linitial_oid(clause->inputcollids);
+
+	/* Collations must match, if relevant */
+	if (!IndexCollMatchesExprColl(idxcollation, expr_coll))
+		return NULL;
+
+	/*
+	 * These syntactic tests are the same as in match_opclause_to_indexcol()
+	 */
+	if (match_index_to_operand(leftop, indexcol, index) &&
+		!bms_is_member(index_relid, pull_varnos(root, rightop)) &&
+		!contain_volatile_functions(rightop))
+	{
+		/* OK, indexkey is on left */
+		var_on_left = true;
+	}
+	else if (match_index_to_operand(rightop, indexcol, index) &&
+			 !bms_is_member(index_relid, pull_varnos(root, leftop)) &&
+			 !contain_volatile_functions(leftop))
+	{
+		/* indexkey is on right, so commute the operator */
+		expr_op = get_commutator(expr_op);
+		if (expr_op == InvalidOid)
+			return NULL;
+		var_on_left = false;
+	}
+	else
+		return NULL;
+
+	/* We're good if the operator is the right type of opfamily member */
+	switch (get_op_opfamily_strategy(expr_op, opfamily))
+	{
+		case BTLessStrategyNumber:
+		case BTLessEqualStrategyNumber:
+		case BTGreaterEqualStrategyNumber:
+		case BTGreaterStrategyNumber:
+			return expand_indexqual_rowcompare(root,
+											   rinfo,
+											   indexcol,
+											   index,
+											   expr_op,
+											   var_on_left);
+	}
+
+	return NULL;
+}
+
+/*
+ * expand_indexqual_rowcompare --- expand a single indexqual condition
+ *		that is a RowCompareExpr
+ *
+ * It's already known that the first column of the row comparison matches
+ * the specified column of the index.  We can use additional columns of the
+ * row comparison as index qualifications, so long as they match the index
+ * in the "same direction", ie, the indexkeys are all on the same side of the
+ * clause and the operators are all the same-type members of the opfamilies.
+ *
+ * If all the columns of the RowCompareExpr match in this way, we just use it
+ * as-is, except for possibly commuting it to put the indexkeys on the left.
+ *
+ * Otherwise, we build a shortened RowCompareExpr (if more than one
+ * column matches) or a simple OpExpr (if the first-column match is all
+ * there is).  In these cases the modified clause is always "<=" or ">="
+ * even when the original was "<" or ">" --- this is necessary to match all
+ * the rows that could match the original.  (We are building a lossy version
+ * of the row comparison when we do this, so we set lossy = true.)
+ *
+ * Note: this is really just the last half of match_rowcompare_to_indexcol,
+ * but we split it out for comprehensibility.
+ */
+static IndexClause *
+expand_indexqual_rowcompare(PlannerInfo *root,
+							RestrictInfo *rinfo,
+							int indexcol,
+							IndexOptInfo *index,
+							Oid expr_op,
+							bool var_on_left)
+{
+	IndexClause *iclause = makeNode(IndexClause);
+	RowCompareExpr *clause = (RowCompareExpr *) rinfo->clause;
+	int			op_strategy;
+	Oid			op_lefttype;
+	Oid			op_righttype;
+	int			matching_cols;
+	List	   *expr_ops;
+	List	   *opfamilies;
+	List	   *lefttypes;
+	List	   *righttypes;
+	List	   *new_ops;
+	List	   *var_args;
+	List	   *non_var_args;
+
+	iclause->rinfo = rinfo;
+	iclause->indexcol = indexcol;
+
+	if (var_on_left)
+	{
+		var_args = clause->largs;
+		non_var_args = clause->rargs;
+	}
+	else
+	{
+		var_args = clause->rargs;
+		non_var_args = clause->largs;
+	}
+
+	get_op_opfamily_properties(expr_op, index->opfamily[indexcol], false,
+							   &op_strategy,
+							   &op_lefttype,
+							   &op_righttype);
+
+	/* Initialize returned list of which index columns are used */
+	iclause->indexcols = list_make1_int(indexcol);
+
+	/* Build lists of ops, opfamilies and operator datatypes in case needed */
+	expr_ops = list_make1_oid(expr_op);
+	opfamilies = list_make1_oid(index->opfamily[indexcol]);
+	lefttypes = list_make1_oid(op_lefttype);
+	righttypes = list_make1_oid(op_righttype);
+
+	/*
+	 * See how many of the remaining columns match some index column in the
+	 * same way.  As in match_clause_to_indexcol(), the "other" side of any
+	 * potential index condition is OK as long as it doesn't use Vars from the
+	 * indexed relation.
+	 */
+	matching_cols = 1;
+
+	while (matching_cols < list_length(var_args))
+	{
+		Node	   *varop = (Node *) list_nth(var_args, matching_cols);
+		Node	   *constop = (Node *) list_nth(non_var_args, matching_cols);
+		int			i;
+
+		expr_op = list_nth_oid(clause->opnos, matching_cols);
+		if (!var_on_left)
+		{
+			/* indexkey is on right, so commute the operator */
+			expr_op = get_commutator(expr_op);
+			if (expr_op == InvalidOid)
+				break;			/* operator is not usable */
+		}
+		if (bms_is_member(index->rel->relid, pull_varnos(root, constop)))
+			break;				/* no good, Var on wrong side */
+		if (contain_volatile_functions(constop))
+			break;				/* no good, volatile comparison value */
+
+		/*
+		 * The Var side can match any key column of the index.
+		 */
+		for (i = 0; i < index->nkeycolumns; i++)
+		{
+			if (match_index_to_operand(varop, i, index) &&
+				get_op_opfamily_strategy(expr_op,
+										 index->opfamily[i]) == op_strategy &&
+				IndexCollMatchesExprColl(index->indexcollations[i],
+										 list_nth_oid(clause->inputcollids,
+													  matching_cols)))
+				break;
+		}
+		if (i >= index->nkeycolumns)
+			break;				/* no match found */
+
+		/* Add column number to returned list */
+		iclause->indexcols = lappend_int(iclause->indexcols, i);
+
+		/* Add operator info to lists */
+		get_op_opfamily_properties(expr_op, index->opfamily[i], false,
+								   &op_strategy,
+								   &op_lefttype,
+								   &op_righttype);
+		expr_ops = lappend_oid(expr_ops, expr_op);
+		opfamilies = lappend_oid(opfamilies, index->opfamily[i]);
+		lefttypes = lappend_oid(lefttypes, op_lefttype);
+		righttypes = lappend_oid(righttypes, op_righttype);
+
+		/* This column matches, keep scanning */
+		matching_cols++;
+	}
+
+	/* Result is non-lossy if all columns are usable as index quals */
+	iclause->lossy = (matching_cols != list_length(clause->opnos));
+
+	/*
+	 * We can use rinfo->clause as-is if we have var on left and it's all
+	 * usable as index quals.
+	 */
+	if (var_on_left && !iclause->lossy)
+		iclause->indexquals = list_make1(rinfo);
+	else
+	{
+		/*
+		 * We have to generate a modified rowcompare (possibly just one
+		 * OpExpr).  The painful part of this is changing < to <= or > to >=,
+		 * so deal with that first.
+		 */
+		if (!iclause->lossy)
+		{
+			/* very easy, just use the commuted operators */
+			new_ops = expr_ops;
+		}
+		else if (op_strategy == BTLessEqualStrategyNumber ||
+				 op_strategy == BTGreaterEqualStrategyNumber)
+		{
+			/* easy, just use the same (possibly commuted) operators */
+			new_ops = list_truncate(expr_ops, matching_cols);
+		}
+		else
+		{
+			ListCell   *opfamilies_cell;
+			ListCell   *lefttypes_cell;
+			ListCell   *righttypes_cell;
+
+			if (op_strategy == BTLessStrategyNumber)
+				op_strategy = BTLessEqualStrategyNumber;
+			else if (op_strategy == BTGreaterStrategyNumber)
+				op_strategy = BTGreaterEqualStrategyNumber;
+			else
+				elog(ERROR, "unexpected strategy number %d", op_strategy);
+			new_ops = NIL;
+			forthree(opfamilies_cell, opfamilies,
+					 lefttypes_cell, lefttypes,
+					 righttypes_cell, righttypes)
+			{
+				Oid			opfam = lfirst_oid(opfamilies_cell);
+				Oid			lefttype = lfirst_oid(lefttypes_cell);
+				Oid			righttype = lfirst_oid(righttypes_cell);
+
+				expr_op = get_opfamily_member(opfam, lefttype, righttype,
+											  op_strategy);
+				if (!OidIsValid(expr_op))	/* should not happen */
+					elog(ERROR, "missing operator %d(%u,%u) in opfamily %u",
+						 op_strategy, lefttype, righttype, opfam);
+				new_ops = lappend_oid(new_ops, expr_op);
+			}
+		}
+
+		/* If we have more than one matching col, create a subset rowcompare */
+		if (matching_cols > 1)
+		{
+			RowCompareExpr *rc = makeNode(RowCompareExpr);
+
+			rc->rctype = (RowCompareType) op_strategy;
+			rc->opnos = new_ops;
+			rc->opfamilies = list_truncate(list_copy(clause->opfamilies),
+										   matching_cols);
+			rc->inputcollids = list_truncate(list_copy(clause->inputcollids),
+											 matching_cols);
+			rc->largs = list_truncate(copyObject(var_args),
+									  matching_cols);
+			rc->rargs = list_truncate(copyObject(non_var_args),
+									  matching_cols);
+			iclause->indexquals = list_make1(make_simple_restrictinfo(root,
+																	  (Expr *) rc));
+		}
+		else
+		{
+			Expr	   *op;
+
+			/* We don't report an index column list in this case */
+			iclause->indexcols = NIL;
+
+			op = make_opclause(linitial_oid(new_ops), BOOLOID, false,
+							   copyObject(linitial(var_args)),
+							   copyObject(linitial(non_var_args)),
+							   InvalidOid,
+							   linitial_oid(clause->inputcollids));
+			iclause->indexquals = list_make1(make_simple_restrictinfo(root, op));
+		}
+	}
+
+	return iclause;
+}
+
+
+/****************************************************************************
+ *				----  ROUTINES TO CHECK ORDERING OPERATORS	----
+ ****************************************************************************/
+
+/*
+ * match_pathkeys_to_index
+ *		Test whether an index can produce output ordered according to the
+ *		given pathkeys using "ordering operators".
+ *
+ * If it can, return a list of suitable ORDER BY expressions, each of the form
+ * "indexedcol operator pseudoconstant", along with an integer list of the
+ * index column numbers (zero based) that each clause would be used with.
+ * NIL lists are returned if the ordering is not achievable this way.
+ *
+ * On success, the result list is ordered by pathkeys, and in fact is
+ * one-to-one with the requested pathkeys.
+ */
+static void
+match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys,
+						List **orderby_clauses_p,
+						List **clause_columns_p)
+{
+	List	   *orderby_clauses = NIL;
+	List	   *clause_columns = NIL;
+	ListCell   *lc1;
+
+	*orderby_clauses_p = NIL;	/* set default results */
+	*clause_columns_p = NIL;
+
+	/* Only indexes with the amcanorderbyop property are interesting here */
+	if (!index->amcanorderbyop)
+		return;
+
+	foreach(lc1, pathkeys)
+	{
+		PathKey    *pathkey = (PathKey *) lfirst(lc1);
+		bool		found = false;
+		ListCell   *lc2;
+
+		/*
+		 * Note: for any failure to match, we just return NIL immediately.
+		 * There is no value in matching just some of the pathkeys.
+		 */
+
+		/* Pathkey must request default sort order for the target opfamily */
+		if (pathkey->pk_strategy != BTLessStrategyNumber ||
+			pathkey->pk_nulls_first)
+			return;
+
+		/* If eclass is volatile, no hope of using an indexscan */
+		if (pathkey->pk_eclass->ec_has_volatile)
+			return;
+
+		/*
+		 * Try to match eclass member expression(s) to index.  Note that child
+		 * EC members are considered, but only when they belong to the target
+		 * relation.  (Unlike regular members, the same expression could be a
+		 * child member of more than one EC.  Therefore, the same index could
+		 * be considered to match more than one pathkey list, which is OK
+		 * here.  See also get_eclass_for_sort_expr.)
+		 */
+		foreach(lc2, pathkey->pk_eclass->ec_members)
+		{
+			EquivalenceMember *member = (EquivalenceMember *) lfirst(lc2);
+			int			indexcol;
+
+			/* No possibility of match if it references other relations */
+			if (!bms_equal(member->em_relids, index->rel->relids))
+				continue;
+
+			/*
+			 * We allow any column of the index to match each pathkey; they
+			 * don't have to match left-to-right as you might expect.  This is
+			 * correct for GiST, and it doesn't matter for SP-GiST because
+			 * that doesn't handle multiple columns anyway, and no other
+			 * existing AMs support amcanorderbyop.  We might need different
+			 * logic in future for other implementations.
+			 */
+			for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
+			{
+				Expr	   *expr;
+
+				expr = match_clause_to_ordering_op(index,
+												   indexcol,
+												   member->em_expr,
+												   pathkey->pk_opfamily);
+				if (expr)
+				{
+					orderby_clauses = lappend(orderby_clauses, expr);
+					clause_columns = lappend_int(clause_columns, indexcol);
+					found = true;
+					break;
+				}
+			}
+
+			if (found)			/* don't want to look at remaining members */
+				break;
+		}
+
+		if (!found)				/* fail if no match for this pathkey */
+			return;
+	}
+
+	*orderby_clauses_p = orderby_clauses;	/* success! */
+	*clause_columns_p = clause_columns;
+}
+
+/*
+ * match_clause_to_ordering_op
+ *	  Determines whether an ordering operator expression matches an
+ *	  index column.
+ *
+ *	  This is similar to, but simpler than, match_clause_to_indexcol.
+ *	  We only care about simple OpExpr cases.  The input is a bare
+ *	  expression that is being ordered by, which must be of the form
+ *	  (indexkey op const) or (const op indexkey) where op is an ordering
+ *	  operator for the column's opfamily.
+ *
+ * 'index' is the index of interest.
+ * 'indexcol' is a column number of 'index' (counting from 0).
+ * 'clause' is the ordering expression to be tested.
+ * 'pk_opfamily' is the btree opfamily describing the required sort order.
+ *
+ * Note that we currently do not consider the collation of the ordering
+ * operator's result.  In practical cases the result type will be numeric
+ * and thus have no collation, and it's not very clear what to match to
+ * if it did have a collation.  The index's collation should match the
+ * ordering operator's input collation, not its result.
+ *
+ * If successful, return 'clause' as-is if the indexkey is on the left,
+ * otherwise a commuted copy of 'clause'.  If no match, return NULL.
+ */
+static Expr *
+match_clause_to_ordering_op(IndexOptInfo *index,
+							int indexcol,
+							Expr *clause,
+							Oid pk_opfamily)
+{
+	Oid			opfamily;
+	Oid			idxcollation;
+	Node	   *leftop,
+			   *rightop;
+	Oid			expr_op;
+	Oid			expr_coll;
+	Oid			sortfamily;
+	bool		commuted;
+
+	Assert(indexcol < index->nkeycolumns);
+
+	opfamily = index->opfamily[indexcol];
+	idxcollation = index->indexcollations[indexcol];
+
+	/*
+	 * Clause must be a binary opclause.
+	 */
+	if (!is_opclause(clause))
+		return NULL;
+	leftop = get_leftop(clause);
+	rightop = get_rightop(clause);
+	if (!leftop || !rightop)
+		return NULL;
+	expr_op = ((OpExpr *) clause)->opno;
+	expr_coll = ((OpExpr *) clause)->inputcollid;
+
+	/*
+	 * We can forget the whole thing right away if wrong collation.
+	 */
+	if (!IndexCollMatchesExprColl(idxcollation, expr_coll))
+		return NULL;
+
+	/*
+	 * Check for clauses of the form: (indexkey operator constant) or
+	 * (constant operator indexkey).
+	 */
+	if (match_index_to_operand(leftop, indexcol, index) &&
+		!contain_var_clause(rightop) &&
+		!contain_volatile_functions(rightop))
+	{
+		commuted = false;
+	}
+	else if (match_index_to_operand(rightop, indexcol, index) &&
+			 !contain_var_clause(leftop) &&
+			 !contain_volatile_functions(leftop))
+	{
+		/* Might match, but we need a commuted operator */
+		expr_op = get_commutator(expr_op);
+		if (expr_op == InvalidOid)
+			return NULL;
+		commuted = true;
+	}
+	else
+		return NULL;
+
+	/*
+	 * Is the (commuted) operator an ordering operator for the opfamily? And
+	 * if so, does it yield the right sorting semantics?
+	 */
+	sortfamily = get_op_opfamily_sortfamily(expr_op, opfamily);
+	if (sortfamily != pk_opfamily)
+		return NULL;
+
+	/* We have a match.  Return clause or a commuted version thereof. */
+	if (commuted)
+	{
+		OpExpr	   *newclause = makeNode(OpExpr);
+
+		/* flat-copy all the fields of clause */
+		memcpy(newclause, clause, sizeof(OpExpr));
+
+		/* commute it */
+		newclause->opno = expr_op;
+		newclause->opfuncid = InvalidOid;
+		newclause->args = list_make2(rightop, leftop);
+
+		clause = (Expr *) newclause;
+	}
+
+	return clause;
+}
+
+
+/****************************************************************************
+ *				----  ROUTINES TO DO PARTIAL INDEX PREDICATE TESTS	----
+ ****************************************************************************/
+
+/*
+ * check_index_predicates
+ *		Set the predicate-derived IndexOptInfo fields for each index
+ *		of the specified relation.
+ *
+ * predOK is set true if the index is partial and its predicate is satisfied
+ * for this query, ie the query's WHERE clauses imply the predicate.
+ *
+ * indrestrictinfo is set to the relation's baserestrictinfo list less any
+ * conditions that are implied by the index's predicate.  (Obviously, for a
+ * non-partial index, this is the same as baserestrictinfo.)  Such conditions
+ * can be dropped from the plan when using the index, in certain cases.
+ *
+ * At one time it was possible for this to get re-run after adding more
+ * restrictions to the rel, thus possibly letting us prove more indexes OK.
+ * That doesn't happen any more (at least not in the core code's usage),
+ * but this code still supports it in case extensions want to mess with the
+ * baserestrictinfo list.  We assume that adding more restrictions can't make
+ * an index not predOK.  We must recompute indrestrictinfo each time, though,
+ * to make sure any newly-added restrictions get into it if needed.
+ */
+void
+check_index_predicates(PlannerInfo *root, RelOptInfo *rel)
+{
+	List	   *clauselist;
+	bool		have_partial;
+	bool		is_target_rel;
+	Relids		otherrels;
+	ListCell   *lc;
+
+	/* Indexes are available only on base or "other" member relations. */
+	Assert(IS_SIMPLE_REL(rel));
+
+	/*
+	 * Initialize the indrestrictinfo lists to be identical to
+	 * baserestrictinfo, and check whether there are any partial indexes.  If
+	 * not, this is all we need to do.
+	 */
+	have_partial = false;
+	foreach(lc, rel->indexlist)
+	{
+		IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
+
+		index->indrestrictinfo = rel->baserestrictinfo;
+		if (index->indpred)
+			have_partial = true;
+	}
+	if (!have_partial)
+		return;
+
+	/*
+	 * Construct a list of clauses that we can assume true for the purpose of
+	 * proving the index(es) usable.  Restriction clauses for the rel are
+	 * always usable, and so are any join clauses that are "movable to" this
+	 * rel.  Also, we can consider any EC-derivable join clauses (which must
+	 * be "movable to" this rel, by definition).
+	 */
+	clauselist = list_copy(rel->baserestrictinfo);
+
+	/* Scan the rel's join clauses */
+	foreach(lc, rel->joininfo)
+	{
+		RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+
+		/* Check if clause can be moved to this rel */
+		if (!join_clause_is_movable_to(rinfo, rel))
+			continue;
+
+		clauselist = lappend(clauselist, rinfo);
+	}
+
+	/*
+	 * Add on any equivalence-derivable join clauses.  Computing the correct
+	 * relid sets for generate_join_implied_equalities is slightly tricky
+	 * because the rel could be a child rel rather than a true baserel, and in
+	 * that case we must remove its parents' relid(s) from all_baserels.
+	 */
+	if (rel->reloptkind == RELOPT_OTHER_MEMBER_REL)
+		otherrels = bms_difference(root->all_baserels,
+								   find_childrel_parents(root, rel));
+	else
+		otherrels = bms_difference(root->all_baserels, rel->relids);
+
+	if (!bms_is_empty(otherrels))
+		clauselist =
+			list_concat(clauselist,
+						generate_join_implied_equalities(root,
+														 bms_union(rel->relids,
+																   otherrels),
+														 otherrels,
+														 rel));
+
+	/*
+	 * Normally we remove quals that are implied by a partial index's
+	 * predicate from indrestrictinfo, indicating that they need not be
+	 * checked explicitly by an indexscan plan using this index.  However, if
+	 * the rel is a target relation of UPDATE/DELETE/MERGE/SELECT FOR UPDATE,
+	 * we cannot remove such quals from the plan, because they need to be in
+	 * the plan so that they will be properly rechecked by EvalPlanQual
+	 * testing.  Some day we might want to remove such quals from the main
+	 * plan anyway and pass them through to EvalPlanQual via a side channel;
+	 * but for now, we just don't remove implied quals at all for target
+	 * relations.
+	 */
+	is_target_rel = (bms_is_member(rel->relid, root->all_result_relids) ||
+					 get_plan_rowmark(root->rowMarks, rel->relid) != NULL);
+
+	/*
+	 * Now try to prove each index predicate true, and compute the
+	 * indrestrictinfo lists for partial indexes.  Note that we compute the
+	 * indrestrictinfo list even for non-predOK indexes; this might seem
+	 * wasteful, but we may be able to use such indexes in OR clauses, cf
+	 * generate_bitmap_or_paths().
+	 */
+	foreach(lc, rel->indexlist)
+	{
+		IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
+		ListCell   *lcr;
+
+		if (index->indpred == NIL)
+			continue;			/* ignore non-partial indexes here */
+
+		if (!index->predOK)		/* don't repeat work if already proven OK */
+			index->predOK = predicate_implied_by(index->indpred, clauselist,
+												 false);
+
+		/* If rel is an update target, leave indrestrictinfo as set above */
+		if (is_target_rel)
+			continue;
+
+		/* Else compute indrestrictinfo as the non-implied quals */
+		index->indrestrictinfo = NIL;
+		foreach(lcr, rel->baserestrictinfo)
+		{
+			RestrictInfo *rinfo = (RestrictInfo *) lfirst(lcr);
+
+			/* predicate_implied_by() assumes first arg is immutable */
+			if (contain_mutable_functions((Node *) rinfo->clause) ||
+				!predicate_implied_by(list_make1(rinfo->clause),
+									  index->indpred, false))
+				index->indrestrictinfo = lappend(index->indrestrictinfo, rinfo);
+		}
+	}
+}
+
+/****************************************************************************
+ *				----  ROUTINES TO CHECK EXTERNALLY-VISIBLE CONDITIONS  ----
+ ****************************************************************************/
+
+/*
+ * ec_member_matches_indexcol
+ *	  Test whether an EquivalenceClass member matches an index column.
+ *
+ * This is a callback for use by generate_implied_equalities_for_column.
+ */
+static bool
+ec_member_matches_indexcol(PlannerInfo *root, RelOptInfo *rel,
+						   EquivalenceClass *ec, EquivalenceMember *em,
+						   void *arg)
+{
+	IndexOptInfo *index = ((ec_member_matches_arg *) arg)->index;
+	int			indexcol = ((ec_member_matches_arg *) arg)->indexcol;
+	Oid			curFamily;
+	Oid			curCollation;
+
+	Assert(indexcol < index->nkeycolumns);
+
+	curFamily = index->opfamily[indexcol];
+	curCollation = index->indexcollations[indexcol];
+
+	/*
+	 * If it's a btree index, we can reject it if its opfamily isn't
+	 * compatible with the EC, since no clause generated from the EC could be
+	 * used with the index.  For non-btree indexes, we can't easily tell
+	 * whether clauses generated from the EC could be used with the index, so
+	 * don't check the opfamily.  This might mean we return "true" for a
+	 * useless EC, so we have to recheck the results of
+	 * generate_implied_equalities_for_column; see
+	 * match_eclass_clauses_to_index.
+	 */
+	if (index->relam == BTREE_AM_OID &&
+		!list_member_oid(ec->ec_opfamilies, curFamily))
+		return false;
+
+	/* We insist on collation match for all index types, though */
+	if (!IndexCollMatchesExprColl(curCollation, ec->ec_collation))
+		return false;
+
+	return match_index_to_operand((Node *) em->em_expr, indexcol, index);
+}
+
+/*
+ * relation_has_unique_index_for
+ *	  Determine whether the relation provably has at most one row satisfying
+ *	  a set of equality conditions, because the conditions constrain all
+ *	  columns of some unique index.
+ *
+ * The conditions can be represented in either or both of two ways:
+ * 1. A list of RestrictInfo nodes, where the caller has already determined
+ * that each condition is a mergejoinable equality with an expression in
+ * this relation on one side, and an expression not involving this relation
+ * on the other.  The transient outer_is_left flag is used to identify which
+ * side we should look at: left side if outer_is_left is false, right side
+ * if it is true.
+ * 2. A list of expressions in this relation, and a corresponding list of
+ * equality operators. The caller must have already checked that the operators
+ * represent equality.  (Note: the operators could be cross-type; the
+ * expressions should correspond to their RHS inputs.)
+ *
+ * The caller need only supply equality conditions arising from joins;
+ * this routine automatically adds in any usable baserestrictinfo clauses.
+ * (Note that the passed-in restrictlist will be destructively modified!)
+ */
+bool
+relation_has_unique_index_for(PlannerInfo *root, RelOptInfo *rel,
+							  List *restrictlist,
+							  List *exprlist, List *oprlist)
+{
+	ListCell   *ic;
+
+	Assert(list_length(exprlist) == list_length(oprlist));
+
+	/* Short-circuit if no indexes... */
+	if (rel->indexlist == NIL)
+		return false;
+
+	/*
+	 * Examine the rel's restriction clauses for usable var = const clauses
+	 * that we can add to the restrictlist.
+	 */
+	foreach(ic, rel->baserestrictinfo)
+	{
+		RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(ic);
+
+		/*
+		 * Note: can_join won't be set for a restriction clause, but
+		 * mergeopfamilies will be if it has a mergejoinable operator and
+		 * doesn't contain volatile functions.
+		 */
+		if (restrictinfo->mergeopfamilies == NIL)
+			continue;			/* not mergejoinable */
+
+		/*
+		 * The clause certainly doesn't refer to anything but the given rel.
+		 * If either side is pseudoconstant then we can use it.
+		 */
+		if (bms_is_empty(restrictinfo->left_relids))
+		{
+			/* righthand side is inner */
+			restrictinfo->outer_is_left = true;
+		}
+		else if (bms_is_empty(restrictinfo->right_relids))
+		{
+			/* lefthand side is inner */
+			restrictinfo->outer_is_left = false;
+		}
+		else
+			continue;
+
+		/* OK, add to list */
+		restrictlist = lappend(restrictlist, restrictinfo);
+	}
+
+	/* Short-circuit the easy case */
+	if (restrictlist == NIL && exprlist == NIL)
+		return false;
+
+	/* Examine each index of the relation ... */
+	foreach(ic, rel->indexlist)
+	{
+		IndexOptInfo *ind = (IndexOptInfo *) lfirst(ic);
+		int			c;
+
+		/*
+		 * If the index is not unique, or not immediately enforced, or if it's
+		 * a partial index, it's useless here.  We're unable to make use of
+		 * predOK partial unique indexes due to the fact that
+		 * check_index_predicates() also makes use of join predicates to
+		 * determine if the partial index is usable. Here we need proofs that
+		 * hold true before any joins are evaluated.
+		 */
+		if (!ind->unique || !ind->immediate || ind->indpred != NIL)
+			continue;
+
+		/*
+		 * Try to find each index column in the lists of conditions.  This is
+		 * O(N^2) or worse, but we expect all the lists to be short.
+		 */
+		for (c = 0; c < ind->nkeycolumns; c++)
+		{
+			bool		matched = false;
+			ListCell   *lc;
+			ListCell   *lc2;
+
+			foreach(lc, restrictlist)
+			{
+				RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+				Node	   *rexpr;
+
+				/*
+				 * The condition's equality operator must be a member of the
+				 * index opfamily, else it is not asserting the right kind of
+				 * equality behavior for this index.  We check this first
+				 * since it's probably cheaper than match_index_to_operand().
+				 */
+				if (!list_member_oid(rinfo->mergeopfamilies, ind->opfamily[c]))
+					continue;
+
+				/*
+				 * XXX at some point we may need to check collations here too.
+				 * For the moment we assume all collations reduce to the same
+				 * notion of equality.
+				 */
+
+				/* OK, see if the condition operand matches the index key */
+				if (rinfo->outer_is_left)
+					rexpr = get_rightop(rinfo->clause);
+				else
+					rexpr = get_leftop(rinfo->clause);
+
+				if (match_index_to_operand(rexpr, c, ind))
+				{
+					matched = true; /* column is unique */
+					break;
+				}
+			}
+
+			if (matched)
+				continue;
+
+			forboth(lc, exprlist, lc2, oprlist)
+			{
+				Node	   *expr = (Node *) lfirst(lc);
+				Oid			opr = lfirst_oid(lc2);
+
+				/* See if the expression matches the index key */
+				if (!match_index_to_operand(expr, c, ind))
+					continue;
+
+				/*
+				 * The equality operator must be a member of the index
+				 * opfamily, else it is not asserting the right kind of
+				 * equality behavior for this index.  We assume the caller
+				 * determined it is an equality operator, so we don't need to
+				 * check any more tightly than this.
+				 */
+				if (!op_in_opfamily(opr, ind->opfamily[c]))
+					continue;
+
+				/*
+				 * XXX at some point we may need to check collations here too.
+				 * For the moment we assume all collations reduce to the same
+				 * notion of equality.
+				 */
+
+				matched = true; /* column is unique */
+				break;
+			}
+
+			if (!matched)
+				break;			/* no match; this index doesn't help us */
+		}
+
+		/* Matched all key columns of this index? */
+		if (c == ind->nkeycolumns)
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * indexcol_is_bool_constant_for_query
+ *
+ * If an index column is constrained to have a constant value by the query's
+ * WHERE conditions, then it's irrelevant for sort-order considerations.
+ * Usually that means we have a restriction clause WHERE indexcol = constant,
+ * which gets turned into an EquivalenceClass containing a constant, which
+ * is recognized as redundant by build_index_pathkeys().  But if the index
+ * column is a boolean variable (or expression), then we are not going to
+ * see WHERE indexcol = constant, because expression preprocessing will have
+ * simplified that to "WHERE indexcol" or "WHERE NOT indexcol".  So we are not
+ * going to have a matching EquivalenceClass (unless the query also contains
+ * "ORDER BY indexcol").  To allow such cases to work the same as they would
+ * for non-boolean values, this function is provided to detect whether the
+ * specified index column matches a boolean restriction clause.
+ */
+bool
+indexcol_is_bool_constant_for_query(PlannerInfo *root,
+									IndexOptInfo *index,
+									int indexcol)
+{
+	ListCell   *lc;
+
+	/* If the index isn't boolean, we can't possibly get a match */
+	if (!IsBooleanOpfamily(index->opfamily[indexcol]))
+		return false;
+
+	/* Check each restriction clause for the index's rel */
+	foreach(lc, index->rel->baserestrictinfo)
+	{
+		RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+
+		/*
+		 * As in match_clause_to_indexcol, never match pseudoconstants to
+		 * indexes.  (It might be semantically okay to do so here, but the
+		 * odds of getting a match are negligible, so don't waste the cycles.)
+		 */
+		if (rinfo->pseudoconstant)
+			continue;
+
+		/* See if we can match the clause's expression to the index column */
+		if (match_boolean_index_clause(root, rinfo, indexcol, index))
+			return true;
+	}
+
+	return false;
+}
+
+
+/****************************************************************************
+ *				----  ROUTINES TO CHECK OPERANDS  ----
+ ****************************************************************************/
+
+/*
+ * match_index_to_operand()
+ *	  Generalized test for a match between an index's key
+ *	  and the operand on one side of a restriction or join clause.
+ *
+ * operand: the nodetree to be compared to the index
+ * indexcol: the column number of the index (counting from 0)
+ * index: the index of interest
+ *
+ * Note that we aren't interested in collations here; the caller must check
+ * for a collation match, if it's dealing with an operator where that matters.
+ *
+ * This is exported for use in selfuncs.c.
+ */
+bool
+match_index_to_operand(Node *operand,
+					   int indexcol,
+					   IndexOptInfo *index)
+{
+	int			indkey;
+
+	/*
+	 * Ignore any RelabelType node above the operand.   This is needed to be
+	 * able to apply indexscanning in binary-compatible-operator cases. Note:
+	 * we can assume there is at most one RelabelType node;
+	 * eval_const_expressions() will have simplified if more than one.
+	 */
+	if (operand && IsA(operand, RelabelType))
+		operand = (Node *) ((RelabelType *) operand)->arg;
+
+	indkey = index->indexkeys[indexcol];
+	if (indkey != 0)
+	{
+		/*
+		 * Simple index column; operand must be a matching Var.
+		 */
+		if (operand && IsA(operand, Var) &&
+			index->rel->relid == ((Var *) operand)->varno &&
+			indkey == ((Var *) operand)->varattno)
+			return true;
+	}
+	else
+	{
+		/*
+		 * Index expression; find the correct expression.  (This search could
+		 * be avoided, at the cost of complicating all the callers of this
+		 * routine; doesn't seem worth it.)
+		 */
+		ListCell   *indexpr_item;
+		int			i;
+		Node	   *indexkey;
+
+		indexpr_item = list_head(index->indexprs);
+		for (i = 0; i < indexcol; i++)
+		{
+			if (index->indexkeys[i] == 0)
+			{
+				if (indexpr_item == NULL)
+					elog(ERROR, "wrong number of index expressions");
+				indexpr_item = lnext(index->indexprs, indexpr_item);
+			}
+		}
+		if (indexpr_item == NULL)
+			elog(ERROR, "wrong number of index expressions");
+		indexkey = (Node *) lfirst(indexpr_item);
+
+		/*
+		 * Does it match the operand?  Again, strip any relabeling.
+		 */
+		if (indexkey && IsA(indexkey, RelabelType))
+			indexkey = (Node *) ((RelabelType *) indexkey)->arg;
+
+		if (equal(indexkey, operand))
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * is_pseudo_constant_for_index()
+ *	  Test whether the given expression can be used as an indexscan
+ *	  comparison value.
+ *
+ * An indexscan comparison value must not contain any volatile functions,
+ * and it can't contain any Vars of the index's own table.  Vars of
+ * other tables are okay, though; in that case we'd be producing an
+ * indexqual usable in a parameterized indexscan.  This is, therefore,
+ * a weaker condition than is_pseudo_constant_clause().
+ *
+ * This function is exported for use by planner support functions,
+ * which will have available the IndexOptInfo, but not any RestrictInfo
+ * infrastructure.  It is making the same test made by functions above
+ * such as match_opclause_to_indexcol(), but those rely where possible
+ * on RestrictInfo information about variable membership.
+ *
+ * expr: the nodetree to be checked
+ * index: the index of interest
+ */
+bool
+is_pseudo_constant_for_index(PlannerInfo *root, Node *expr, IndexOptInfo *index)
+{
+	/* pull_varnos is cheaper than volatility check, so do that first */
+	if (bms_is_member(index->rel->relid, pull_varnos(root, expr)))
+		return false;			/* no good, contains Var of table */
+	if (contain_volatile_functions(expr))
+		return false;			/* no good, volatile comparison value */
+	return true;
+}