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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:17:33 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:17:33 +0000
commit5e45211a64149b3c659b90ff2de6fa982a5a93ed (patch)
tree739caf8c461053357daa9f162bef34516c7bf452 /src/backend/optimizer/path/indxpath.c
parentInitial commit. (diff)
downloadpostgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.tar.xz
postgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.zip
Adding upstream version 15.5.upstream/15.5
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/backend/optimizer/path/indxpath.c')
-rw-r--r--src/backend/optimizer/path/indxpath.c3817
1 files changed, 3817 insertions, 0 deletions
diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
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+/*-------------------------------------------------------------------------
+ *
+ * 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;
+}