/*------------------------------------------------------------------------- * * indxpath.c * Routines to determine which indexes are usable for scanning a * given relation, and create Paths accordingly. * * Portions Copyright (c) 1996-2025, 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 #include "access/stratnum.h" #include "access/sysattr.h" #include "catalog/pg_am.h" #include "catalog/pg_amop.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 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); 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 bool IsBooleanOpfamily(Oid opfamily); 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 *match_orclause_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; /* 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); all_path_outers = list_append_unique(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 (list_member(*considered_relids, clause_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 (list_member(*considered_relids, 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; } /* * 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. */ static void get_index_paths(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *clauses, List **bitindexpaths) { List *indexpaths; bool skip_nonnative_saop = false; ListCell *lc; /* * Build simple index paths using the clauses. Allow ScalarArrayOpExpr * clauses only if the index AM supports them natively. */ indexpaths = build_index_paths(root, rel, index, clauses, index->predOK, ST_ANYSCAN, &skip_nonnative_saop); /* * 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); *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. * * '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 */ static List * build_index_paths(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *clauses, bool useful_predicate, ScanTypeControl scantype, bool *skip_nonnative_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 pathkeys_possibly_useful; bool index_is_ordered; bool index_only_scan; int indexcol; Assert(skip_nonnative_saop != NULL || scantype == ST_BITMAPSCAN); /* * 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. * * 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; 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; if (skip_nonnative_saop && !index->amsearcharray && IsA(rinfo->clause, ScalarArrayOpExpr)) { /* * Caller asked us to generate IndexPaths that omit any * ScalarArrayOpExpr clauses when the underlying index AM * lacks native support. * * We must omit this clause (and tell caller about it). */ *skip_nonnative_saop = true; continue; } /* 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); /* 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. */ pathkeys_possibly_useful = (scantype != ST_BITMAPSCAN && 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 or at * least some prefix thereof. Matching to just a prefix of the * query_pathkeys will allow an incremental sort to be considered on * the index's partially sorted results. */ match_pathkeys_to_index(index, root->query_pathkeys, &orderbyclauses, &orderbyclausecols); if (list_length(root->query_pathkeys) == list_length(orderbyclauses)) useful_pathkeys = root->query_pathkeys; else useful_pathkeys = list_copy_head(root->query_pathkeys, list_length(orderbyclauses)); } 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, ForwardScanDirection, 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, ForwardScanDirection, 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); result = list_concat(result, indexpaths); } return result; } /* * Utility structure used to group similar OR-clause arguments in * group_similar_or_args(). It represents information about the OR-clause * argument and its matching index key. */ typedef struct { int indexnum; /* index of the matching index, or -1 if no * matching index */ int colnum; /* index of the matching column, or -1 if no * matching index */ Oid opno; /* OID of the OpClause operator, or InvalidOid * if not an OpExpr */ Oid inputcollid; /* OID of the OpClause input collation */ int argindex; /* index of the clause in the list of * arguments */ int groupindex; /* value of argindex for the fist clause in * the group of similar clauses */ } OrArgIndexMatch; /* * Comparison function for OrArgIndexMatch which provides sort order placing * similar OR-clause arguments together. */ static int or_arg_index_match_cmp(const void *a, const void *b) { const OrArgIndexMatch *match_a = (const OrArgIndexMatch *) a; const OrArgIndexMatch *match_b = (const OrArgIndexMatch *) b; if (match_a->indexnum < match_b->indexnum) return -1; else if (match_a->indexnum > match_b->indexnum) return 1; if (match_a->colnum < match_b->colnum) return -1; else if (match_a->colnum > match_b->colnum) return 1; if (match_a->opno < match_b->opno) return -1; else if (match_a->opno > match_b->opno) return 1; if (match_a->inputcollid < match_b->inputcollid) return -1; else if (match_a->inputcollid > match_b->inputcollid) return 1; if (match_a->argindex < match_b->argindex) return -1; else if (match_a->argindex > match_b->argindex) return 1; return 0; } /* * Another comparison function for OrArgIndexMatch. It sorts groups together * using groupindex. The group items are then sorted by argindex. */ static int or_arg_index_match_cmp_group(const void *a, const void *b) { const OrArgIndexMatch *match_a = (const OrArgIndexMatch *) a; const OrArgIndexMatch *match_b = (const OrArgIndexMatch *) b; if (match_a->groupindex < match_b->groupindex) return -1; else if (match_a->groupindex > match_b->groupindex) return 1; if (match_a->argindex < match_b->argindex) return -1; else if (match_a->argindex > match_b->argindex) return 1; return 0; } /* * group_similar_or_args * Transform incoming OR-restrictinfo into a list of sub-restrictinfos, * each of them containing a subset of similar OR-clause arguments from * the source rinfo. * * Similar OR-clause arguments are of the form "indexkey op constant" having * the same indexkey, operator, and collation. Constant may comprise either * Const or Param. It may be employed later, during the * match_clause_to_indexcol() to transform the whole OR-sub-rinfo to an SAOP * clause. * * Returns the processed list of OR-clause arguments. */ static List * group_similar_or_args(PlannerInfo *root, RelOptInfo *rel, RestrictInfo *rinfo) { int n; int i; int group_start; OrArgIndexMatch *matches; bool matched = false; ListCell *lc; ListCell *lc2; List *orargs; List *result = NIL; Index relid = rel->relid; Assert(IsA(rinfo->orclause, BoolExpr)); orargs = ((BoolExpr *) rinfo->orclause)->args; n = list_length(orargs); /* * To avoid N^2 behavior, take utility pass along the list of OR-clause * arguments. For each argument, fill the OrArgIndexMatch structure, * which will be used to sort these arguments at the next step. */ i = -1; matches = (OrArgIndexMatch *) palloc(sizeof(OrArgIndexMatch) * n); foreach(lc, orargs) { Node *arg = lfirst(lc); RestrictInfo *argrinfo; OpExpr *clause; Oid opno; Node *leftop, *rightop; Node *nonConstExpr; int indexnum; int colnum; i++; matches[i].argindex = i; matches[i].groupindex = i; matches[i].indexnum = -1; matches[i].colnum = -1; matches[i].opno = InvalidOid; matches[i].inputcollid = InvalidOid; if (!IsA(arg, RestrictInfo)) continue; argrinfo = castNode(RestrictInfo, arg); /* Only operator clauses can match */ if (!IsA(argrinfo->clause, OpExpr)) continue; clause = (OpExpr *) argrinfo->clause; opno = clause->opno; /* Only binary operators can match */ if (list_length(clause->args) != 2) continue; /* * Ignore any RelabelType node above the operands. 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. */ leftop = get_leftop(clause); if (IsA(leftop, RelabelType)) leftop = (Node *) ((RelabelType *) leftop)->arg; rightop = get_rightop(clause); if (IsA(rightop, RelabelType)) rightop = (Node *) ((RelabelType *) rightop)->arg; /* * Check for clauses of the form: (indexkey operator constant) or * (constant operator indexkey). But we don't know a particular index * yet. Therefore, we try to distinguish the potential index key and * constant first, then search for a matching index key among all * indexes. */ if (bms_is_member(relid, argrinfo->right_relids) && !bms_is_member(relid, argrinfo->left_relids) && !contain_volatile_functions(leftop)) { opno = get_commutator(opno); if (!OidIsValid(opno)) { /* commutator doesn't exist, we can't reverse the order */ continue; } nonConstExpr = rightop; } else if (bms_is_member(relid, argrinfo->left_relids) && !bms_is_member(relid, argrinfo->right_relids) && !contain_volatile_functions(rightop)) { nonConstExpr = leftop; } else { continue; } /* * Match non-constant part to the index key. It's possible that a * single non-constant part matches multiple index keys. It's OK, we * just stop with first matching index key. Given that this choice is * determined the same for every clause, we will group similar clauses * together anyway. */ indexnum = 0; foreach(lc2, rel->indexlist) { IndexOptInfo *index = (IndexOptInfo *) lfirst(lc2); /* * Ignore index if it doesn't support bitmap scans or SAOP * clauses. */ if (!index->amhasgetbitmap || !index->amsearcharray) continue; for (colnum = 0; colnum < index->nkeycolumns; colnum++) { if (match_index_to_operand(nonConstExpr, colnum, index)) { matches[i].indexnum = indexnum; matches[i].colnum = colnum; matches[i].opno = opno; matches[i].inputcollid = clause->inputcollid; matched = true; break; } } /* * Stop looping through the indexes, if we managed to match * nonConstExpr to any index column. */ if (matches[i].indexnum >= 0) break; indexnum++; } } /* * Fast-path check: if no clause is matching to the index column, we can * just give up at this stage and return the clause list as-is. */ if (!matched) { pfree(matches); return orargs; } /* * Sort clauses to make similar clauses go together. But at the same * time, we would like to change the order of clauses as little as * possible. To do so, we reorder each group of similar clauses so that * the first item of the group stays in place, and all the other items are * moved after it. So, if there are no similar clauses, the order of * clauses stays the same. When there are some groups, required * reordering happens while the rest of the clauses remain in their * places. That is achieved by assigning a 'groupindex' to each clause: * the number of the first item in the group in the original clause list. */ qsort(matches, n, sizeof(OrArgIndexMatch), or_arg_index_match_cmp); /* Assign groupindex to the sorted clauses */ for (i = 1; i < n; i++) { /* * When two clauses are similar and should belong to the same group, * copy the 'groupindex' from the previous clause. Given we are * considering clauses in direct order, all the clauses would have a * 'groupindex' equal to the 'groupindex' of the first clause in the * group. */ if (matches[i].indexnum == matches[i - 1].indexnum && matches[i].colnum == matches[i - 1].colnum && matches[i].opno == matches[i - 1].opno && matches[i].inputcollid == matches[i - 1].inputcollid && matches[i].indexnum != -1) matches[i].groupindex = matches[i - 1].groupindex; } /* Re-sort clauses first by groupindex then by argindex */ qsort(matches, n, sizeof(OrArgIndexMatch), or_arg_index_match_cmp_group); /* * Group similar clauses into single sub-restrictinfo. Side effect: the * resulting list of restrictions will be sorted by indexnum and colnum. */ group_start = 0; for (i = 1; i <= n; i++) { /* Check if it's a group boundary */ if (group_start >= 0 && (i == n || matches[i].indexnum != matches[group_start].indexnum || matches[i].colnum != matches[group_start].colnum || matches[i].opno != matches[group_start].opno || matches[i].inputcollid != matches[group_start].inputcollid || matches[i].indexnum == -1)) { /* * One clause in group: add it "as is" to the upper-level OR. */ if (i - group_start == 1) { result = lappend(result, list_nth(orargs, matches[group_start].argindex)); } else { /* * Two or more clauses in a group: create a nested OR. */ List *args = NIL; List *rargs = NIL; RestrictInfo *subrinfo; int j; Assert(i - group_start >= 2); /* Construct the list of nested OR arguments */ for (j = group_start; j < i; j++) { Node *arg = list_nth(orargs, matches[j].argindex); rargs = lappend(rargs, arg); if (IsA(arg, RestrictInfo)) args = lappend(args, ((RestrictInfo *) arg)->clause); else args = lappend(args, arg); } /* Construct the nested OR and wrap it with RestrictInfo */ subrinfo = make_plain_restrictinfo(root, make_orclause(args), make_orclause(rargs), rinfo->is_pushed_down, rinfo->has_clone, rinfo->is_clone, rinfo->pseudoconstant, rinfo->security_level, rinfo->required_relids, rinfo->incompatible_relids, rinfo->outer_relids); result = lappend(result, subrinfo); } group_start = i; } } pfree(matches); return result; } /* * make_bitmap_paths_for_or_group * Generate bitmap paths for a group of similar OR-clause arguments * produced by group_similar_or_args(). * * This function considers two cases: (1) matching a group of clauses to * the index as a whole, and (2) matching the individual clauses one-by-one. * (1) typically comprises an optimal solution. If not, (2) typically * comprises fair alternative. * * Ideally, we could consider all arbitrary splits of arguments into * subgroups, but that could lead to unacceptable computational complexity. * This is why we only consider two cases of above. */ static List * make_bitmap_paths_for_or_group(PlannerInfo *root, RelOptInfo *rel, RestrictInfo *ri, List *other_clauses) { List *jointlist = NIL; List *splitlist = NIL; ListCell *lc; List *orargs; List *args = ((BoolExpr *) ri->orclause)->args; Cost jointcost = 0.0, splitcost = 0.0; Path *bitmapqual; List *indlist; /* * First, try to match the whole group to the one index. */ orargs = list_make1(ri); indlist = build_paths_for_OR(root, rel, orargs, other_clauses); if (indlist != NIL) { bitmapqual = choose_bitmap_and(root, rel, indlist); jointcost = bitmapqual->total_cost; jointlist = list_make1(bitmapqual); } /* * If we manage to find a bitmap scan, which uses the group of OR-clause * arguments as a whole, we can skip matching OR-clause arguments * one-by-one as long as there are no other clauses, which can bring more * efficiency to one-by-one case. */ if (jointlist != NIL && other_clauses == NIL) return jointlist; /* * Also try to match all containing clauses one-by-one. */ foreach(lc, args) { orargs = list_make1(lfirst(lc)); indlist = build_paths_for_OR(root, rel, orargs, other_clauses); if (indlist == NIL) { splitlist = NIL; break; } bitmapqual = choose_bitmap_and(root, rel, indlist); splitcost += bitmapqual->total_cost; splitlist = lappend(splitlist, bitmapqual); } /* * Pick the best option. */ if (splitlist == NIL) return jointlist; else if (jointlist == NIL) return splitlist; else return (jointcost < splitcost) ? jointlist : splitlist; } /* * 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; List *groupedArgs; List *inner_other_clauses = NIL; /* 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; /* * Group the similar OR-clause arguments into dedicated RestrictInfos, * because each of those RestrictInfos has a chance to match the index * as a whole. */ groupedArgs = group_similar_or_args(root, rel, rinfo); if (groupedArgs != ((BoolExpr *) rinfo->orclause)->args) { /* * Some parts of the rinfo were probably grouped. In this case, * we have a set of sub-rinfos that together are an exact * duplicate of rinfo. Thus, we need to remove the rinfo from * other clauses. match_clauses_to_index detects duplicated * iclauses by comparing pointers to original rinfos that would be * different. So, we must delete rinfo to avoid de-facto * duplicated clauses in the index clauses list. */ inner_other_clauses = list_delete(list_copy(all_clauses), rinfo); } foreach(j, groupedArgs) { 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 if (restriction_is_or_clause(castNode(RestrictInfo, orarg))) { RestrictInfo *ri = castNode(RestrictInfo, orarg); /* * Generate bitmap paths for the group of similar OR-clause * arguments. */ indlist = make_bitmap_paths_for_or_group(root, rel, ri, inner_other_clauses); if (indlist == NIL) { pathlist = NIL; break; } else { pathlist = list_concat(pathlist, indlist); continue; } } else { RestrictInfo *ri = castNode(RestrictInfo, orarg); List *orargs; orargs = list_make1(ri); 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 (inner_other_clauses != NIL) list_free(inner_other_clauses); /* * 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. * They also might be processed by match_clause_to_index() as a whole. */ 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. Use * list_append_unique_ptr() here to avoid possible duplicates when * processing the same clauses with different indexes. */ if (restriction_is_or_clause(rinfo)) *joinorclauses = list_append_unique_ptr(*joinorclauses, rinfo); 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, &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]) { 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)". * * It is also possible to match a list of OR clauses if it might be * transformed into a single ScalarArrayOpExpr clause. On success, * the returning index clause will contain a transformed clause. * * 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: This routine always returns NULL if the clause is an AND clause. * Higher-level routines deal with OR and AND clauses. OR clause can be * matched as a whole by match_orclause_to_indexcol() though. */ 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, * RowCompareExpr, or OR-clause that could be converted to SAOP. 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 (restriction_is_or_clause(rinfo)) { return match_orclause_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; } /* * IsBooleanOpfamily * Detect whether an opfamily supports boolean equality as an operator. * * If the opfamily OID is in the range of built-in objects, we can rely * on hard-wired knowledge of which built-in opfamilies support this. * For extension opfamilies, there's no choice but to do a catcache lookup. */ static bool IsBooleanOpfamily(Oid opfamily) { if (opfamily < FirstNormalObjectId) return IsBuiltinBooleanOpfamily(opfamily); else return op_in_opfamily(BooleanEqualOperator, opfamily); } /* * 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; } /* * match_orclause_to_indexcol() * Handles the OR-expr case for match_clause_to_indexcol() in the case * when it could be transformed to ScalarArrayOpExpr. * * In this routine, we attempt to transform a list of OR-clause args into a * single SAOP expression matching the target index column. On success, * return an IndexClause, containing the transformed expression or NULL, * if failed. */ static IndexClause * match_orclause_to_indexcol(PlannerInfo *root, RestrictInfo *rinfo, int indexcol, IndexOptInfo *index) { ListCell *lc; BoolExpr *orclause = (BoolExpr *) rinfo->orclause; Node *indexExpr = NULL; List *consts = NIL; ScalarArrayOpExpr *saopexpr = NULL; Oid matchOpno = InvalidOid; IndexClause *iclause; Oid consttype = InvalidOid; Oid arraytype = InvalidOid; Oid inputcollid = InvalidOid; bool firstTime = true; bool haveNonConst = false; Index indexRelid = index->rel->relid; Assert(IsA(orclause, BoolExpr)); Assert(orclause->boolop == OR_EXPR); /* Ignore index if it doesn't support SAOP clauses */ if (!index->amsearcharray) return NULL; /* * Try to convert a list of OR-clauses to a single SAOP expression. Each * OR entry must be in the form: (indexkey operator constant) or (constant * operator indexkey). Operators of all the entries must match. To be * effective, give up on the first non-matching entry. Exit is * implemented as a break from the loop, which is catched afterwards. */ foreach(lc, orclause->args) { RestrictInfo *subRinfo; OpExpr *subClause; Oid opno; Node *leftop, *rightop; Node *constExpr; if (!IsA(lfirst(lc), RestrictInfo)) break; subRinfo = (RestrictInfo *) lfirst(lc); /* Only operator clauses can match */ if (!IsA(subRinfo->clause, OpExpr)) break; subClause = (OpExpr *) subRinfo->clause; opno = subClause->opno; /* Only binary operators can match */ if (list_length(subClause->args) != 2) break; /* * The parameters below must match between sub-rinfo and its parent as * make_restrictinfo() fills them with the same values, and further * modifications are also the same for the whole subtree. However, * still make a sanity check. */ Assert(subRinfo->is_pushed_down == rinfo->is_pushed_down); Assert(subRinfo->is_clone == rinfo->is_clone); Assert(subRinfo->security_level == rinfo->security_level); Assert(bms_equal(subRinfo->incompatible_relids, rinfo->incompatible_relids)); Assert(bms_equal(subRinfo->outer_relids, rinfo->outer_relids)); /* * Also, check that required_relids in sub-rinfo is subset of parent's * required_relids. */ Assert(bms_is_subset(subRinfo->required_relids, rinfo->required_relids)); /* Only the operator returning a boolean suit the transformation. */ if (get_op_rettype(opno) != BOOLOID) break; /* * Check for clauses of the form: (indexkey operator constant) or * (constant operator indexkey). See match_clause_to_indexcol's notes * about const-ness. */ leftop = (Node *) linitial(subClause->args); rightop = (Node *) lsecond(subClause->args); if (match_index_to_operand(leftop, indexcol, index) && !bms_is_member(indexRelid, subRinfo->right_relids) && !contain_volatile_functions(rightop)) { indexExpr = leftop; constExpr = rightop; } else if (match_index_to_operand(rightop, indexcol, index) && !bms_is_member(indexRelid, subRinfo->left_relids) && !contain_volatile_functions(leftop)) { opno = get_commutator(opno); if (!OidIsValid(opno)) { /* commutator doesn't exist, we can't reverse the order */ break; } indexExpr = rightop; constExpr = leftop; } else { break; } /* * Ignore any RelabelType node above the operands. 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 (IsA(constExpr, RelabelType)) constExpr = (Node *) ((RelabelType *) constExpr)->arg; if (IsA(indexExpr, RelabelType)) indexExpr = (Node *) ((RelabelType *) indexExpr)->arg; /* Forbid transformation for composite types, records. */ if (type_is_rowtype(exprType(constExpr)) || type_is_rowtype(exprType(indexExpr))) break; /* * Save information about the operator, type, and collation for the * first matching qual. Then, check that subsequent quals match the * first. */ if (firstTime) { matchOpno = opno; consttype = exprType(constExpr); arraytype = get_array_type(consttype); inputcollid = subClause->inputcollid; /* * Check that the operator is presented in the opfamily and that * the expression collation matches the index collation. Also, * there must be an array type to construct an array later. */ if (!IndexCollMatchesExprColl(index->indexcollations[indexcol], inputcollid) || !op_in_opfamily(matchOpno, index->opfamily[indexcol]) || !OidIsValid(arraytype)) break; firstTime = false; } else { if (opno != matchOpno || inputcollid != subClause->inputcollid || consttype != exprType(constExpr)) break; } /* * Check if our list of constants in match_clause_to_indexcol's * understanding of const-ness have something other than Const. */ if (!IsA(constExpr, Const)) haveNonConst = true; consts = lappend(consts, constExpr); } /* * Catch the break from the loop above. Normally, a foreach() loop ends * up with a NULL list cell. A non-NULL list cell indicates a break from * the foreach() loop. Free the consts list and return NULL then. */ if (lc != NULL) { list_free(consts); return NULL; } saopexpr = make_SAOP_expr(matchOpno, indexExpr, consttype, inputcollid, inputcollid, consts, haveNonConst); /* * Finally, build an IndexClause based on the SAOP node. Use * make_simple_restrictinfo() to get RestrictInfo with clean selectivity * estimations, because they may differ from the estimation made for an OR * clause. Although it is not a lossy expression, keep the original rinfo * in iclause->rinfo as prescribed. */ iclause = makeNode(IndexClause); iclause->rinfo = rinfo; iclause->indexquals = list_make1(make_simple_restrictinfo(root, &saopexpr->xpr)); iclause->lossy = false; iclause->indexcol = indexcol; iclause->indexcols = NIL; return iclause; } /* * 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->cmptype = (CompareType) op_strategy; rc->opnos = new_ops; rc->opfamilies = list_copy_head(clause->opfamilies, matching_cols); rc->inputcollids = list_copy_head(clause->inputcollids, matching_cols); rc->largs = list_copy_head(var_args, matching_cols); rc->rargs = list_copy_head(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 * For the given 'index' and 'pathkeys', output 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. * * This attempts to find an ORDER BY and index column number for all items in * the pathkey list, however, if we're unable to match any given pathkey to an * index column, we return just the ones matched by the function so far. This * allows callers who are interested in partial matches to get them. Callers * can determine a partial match vs a full match by checking the outputted * list lengths. A full match will have one item in the output lists for each * item in the given 'pathkeys' list. */ static void match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys, List **orderby_clauses_p, List **clause_columns_p) { 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; EquivalenceMemberIterator it; EquivalenceMember *member; /* Pathkey must request default sort order for the target opfamily */ if (pathkey->pk_cmptype != COMPARE_LT || 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.) */ setup_eclass_member_iterator(&it, pathkey->pk_eclass, index->rel->relids); while ((member = eclass_member_iterator_next(&it)) != NULL) { 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_p = lappend(*orderby_clauses_p, expr); *clause_columns_p = lappend_int(*clause_columns_p, indexcol); found = true; break; } } if (found) /* don't want to look at remaining members */ break; } /* * Return the matches found so far when this pathkey couldn't be * matched to the index. */ if (!found) return; } } /* * 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 subtract its parents' relid(s) from all_query_rels. * Additionally, we mustn't consider clauses that are only computable * after outer joins that can null the rel. */ if (rel->reloptkind == RELOPT_OTHER_MEMBER_REL) otherrels = bms_difference(root->all_query_rels, find_childrel_parents(root, rel)); else otherrels = bms_difference(root->all_query_rels, rel->relids); otherrels = bms_del_members(otherrels, rel->nulling_relids); if (!bms_is_empty(otherrels)) clauselist = list_concat(clauselist, generate_join_implied_equalities(root, bms_union(rel->relids, otherrels), otherrels, rel, NULL)); /* * 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) { return relation_has_unique_index_ext(root, rel, restrictlist, exprlist, oprlist, NULL); } /* * relation_has_unique_index_ext * Same as relation_has_unique_index_for(), but supports extra_clauses * parameter. If extra_clauses isn't NULL, return baserestrictinfo clauses * which were used to derive uniqueness. */ bool relation_has_unique_index_ext(PlannerInfo *root, RelOptInfo *rel, List *restrictlist, List *exprlist, List *oprlist, List **extra_clauses) { 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; List *exprs = NIL; /* * 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 */ if (bms_membership(rinfo->clause_relids) == BMS_SINGLETON) { MemoryContext oldMemCtx = MemoryContextSwitchTo(root->planner_cxt); /* * Add filter clause into a list allowing caller to * know if uniqueness have made not only by join * clauses. */ Assert(bms_is_empty(rinfo->left_relids) || bms_is_empty(rinfo->right_relids)); if (extra_clauses) exprs = lappend(exprs, rinfo); MemoryContextSwitchTo(oldMemCtx); } 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) { if (extra_clauses) *extra_clauses = exprs; 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 && ((Var *) operand)->varnullingrels == NULL) 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; }