/*------------------------------------------------------------------------- * * indxpath.c * Routines to determine which indexes are usable for scanning a * given relation, and create Paths accordingly. * * Portions Copyright (c) 1996-2015, 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_collation.h" #include "catalog/pg_operator.h" #include "catalog/pg_opfamily.h" #include "catalog/pg_type.h" #include "nodes/makefuncs.h" #include "optimizer/clauses.h" #include "optimizer/cost.h" #include "optimizer/pathnode.h" #include "optimizer/paths.h" #include "optimizer/predtest.h" #include "optimizer/restrictinfo.h" #include "optimizer/var.h" #include "utils/builtins.h" #include "utils/bytea.h" #include "utils/lsyscache.h" #include "utils/pg_locale.h" #include "utils/selfuncs.h" #define IsBooleanOpfamily(opfamily) \ ((opfamily) == BOOL_BTREE_FAM_OID || (opfamily) == BOOL_HASH_FAM_OID) #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 RestrictInfos, one 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 */ } PathClauseUsage; /* Callback argument for ec_member_matches_indexcol */ typedef struct { IndexOptInfo *index; /* index we're considering */ int indexcol; /* index column we want to match to */ } ec_member_matches_arg; static void consider_index_join_clauses(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *rclauseset, IndexClauseSet *jclauseset, IndexClauseSet *eclauseset, List **bitindexpaths); static void consider_index_join_outer_rels(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *rclauseset, IndexClauseSet *jclauseset, IndexClauseSet *eclauseset, List **bitindexpaths, List *indexjoinclauses, int considered_clauses, List **considered_relids); static void get_join_index_paths(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *rclauseset, IndexClauseSet *jclauseset, IndexClauseSet *eclauseset, List **bitindexpaths, Relids relids, List **considered_relids); static bool eclass_already_used(EquivalenceClass *parent_ec, Relids oldrelids, List *indexjoinclauses); static bool bms_equal_any(Relids relids, List *relids_list); static void get_index_paths(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *clauses, List **bitindexpaths); static List *build_index_paths(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *clauses, bool useful_predicate, ScanTypeControl scantype, bool *skip_nonnative_saop, bool *skip_lower_saop); static List *build_paths_for_OR(PlannerInfo *root, RelOptInfo *rel, List *clauses, List *other_clauses); static List *generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel, List *clauses, List *other_clauses); static Path *choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel, List *paths); static int path_usage_comparator(const void *a, const void *b); static Cost bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath); static Cost bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths); static PathClauseUsage *classify_index_clause_usage(Path *path, List **clauselist); static Relids get_bitmap_tree_required_outer(Path *bitmapqual); 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(RelOptInfo *rel, 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(IndexOptInfo *index, List *clauses, IndexClauseSet *clauseset); static void match_clause_to_index(IndexOptInfo *index, RestrictInfo *rinfo, IndexClauseSet *clauseset); static bool match_clause_to_indexcol(IndexOptInfo *index, int indexcol, RestrictInfo *rinfo); static bool is_indexable_operator(Oid expr_op, Oid opfamily, bool indexkey_on_left); static bool match_rowcompare_to_indexcol(IndexOptInfo *index, int indexcol, Oid opfamily, Oid idxcollation, RowCompareExpr *clause); 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); static bool match_boolean_index_clause(Node *clause, int indexcol, IndexOptInfo *index); static bool match_special_index_operator(Expr *clause, Oid opfamily, Oid idxcollation, bool indexkey_on_left); static Expr *expand_boolean_index_clause(Node *clause, int indexcol, IndexOptInfo *index); static List *expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily, Oid idxcollation); static RestrictInfo *expand_indexqual_rowcompare(RestrictInfo *rinfo, IndexOptInfo *index, int indexcol); static List *prefix_quals(Node *leftop, Oid opfamily, Oid collation, Const *prefix, Pattern_Prefix_Status pstatus); static List *network_prefix_quals(Node *leftop, Oid expr_op, Oid opfamily, Datum rightop); static Datum string_to_datum(const char *str, Oid datatype); static Const *string_to_const(const char *str, Oid datatype); /* * 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_partial_indexes() 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->ncolumns <= 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(rel, 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); add_path(rel, (Path *) bpath); } /* * 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 *path_outer; List *all_path_outers; ListCell *lc; /* * path_outer holds the parameterization of each path in bitjoinpaths * (to save recalculating that several times), while all_path_outers * holds all distinct parameterization sets. */ path_outer = all_path_outers = NIL; foreach(lc, bitjoinpaths) { Path *path = (Path *) lfirst(lc); Relids required_outer; required_outer = get_bitmap_tree_required_outer(path); path_outer = lappend(path_outer, required_outer); if (!bms_equal_any(required_outer, all_path_outers)) all_path_outers = lappend(all_path_outers, required_outer); } /* Now, for each distinct parameterization set ... */ foreach(lc, all_path_outers) { Relids max_outers = (Relids) lfirst(lc); List *this_path_set; Path *bitmapqual; Relids required_outer; double loop_count; BitmapHeapPath *bpath; ListCell *lcp; ListCell *lco; /* Identify all the bitmap join paths needing no more than that */ this_path_set = NIL; forboth(lcp, bitjoinpaths, lco, path_outer) { Path *path = (Path *) lfirst(lcp); Relids p_outers = (Relids) lfirst(lco); if (bms_is_subset(p_outers, 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 = get_bitmap_tree_required_outer(bitmapqual); loop_count = get_loop_count(root, rel->relid, required_outer); bpath = create_bitmap_heap_path(root, rel, bitmapqual, required_outer, loop_count); 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->ncolumns; 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 RestrictInfos 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) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); Relids clause_relids = rinfo->clause_relids; ListCell *lc2; /* If we already tried its relids set, no need to do so again */ if (bms_equal_any(clause_relids, *considered_relids)) continue; /* * Generate the union of this clause's relids set with each * previously-tried set. This ensures we try this clause along with * every interesting subset of previous clauses. However, to avoid * exponential growth of planning time when there are many clauses, * limit the number of relid sets accepted to 10 * considered_clauses. * * Note: get_join_index_paths adds entries to *considered_relids, but * it prepends them to the list, so that we won't visit new entries * during the inner foreach loop. No real harm would be done if we * did, since the subset check would reject them; but it would waste * some cycles. */ foreach(lc2, *considered_relids) { Relids oldrelids = (Relids) lfirst(lc2); /* * 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 (rinfo->parent_ec && eclass_already_used(rinfo->parent_ec, oldrelids, indexjoinclauses)) continue; /* * If the number of relid sets considered exceeds our heuristic * limit, stop considering combinations of clauses. We'll still * consider the current clause alone, though (below this loop). */ if (list_length(*considered_relids) >= 10 * considered_clauses) break; /* OK, try the union set */ get_join_index_paths(root, rel, index, rclauseset, jclauseset, eclauseset, bitindexpaths, bms_union(clause_relids, oldrelids), considered_relids); } /* Also try this set of relids by itself */ get_join_index_paths(root, rel, index, rclauseset, jclauseset, eclauseset, bitindexpaths, clause_relids, considered_relids); } } /* * get_join_index_paths * Generate index paths using clauses from the specified outer relations. * In addition to generating paths, relids is added to *considered_relids * if not already present. * * Workhorse for consider_index_join_clauses; see notes therein for rationale. * * 'rel', 'index', 'rclauseset', 'jclauseset', 'eclauseset', * 'bitindexpaths', 'considered_relids' as above * 'relids' is the current set of relids to consider (the target rel plus * one or more outer rels) */ static void get_join_index_paths(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *rclauseset, IndexClauseSet *jclauseset, IndexClauseSet *eclauseset, List **bitindexpaths, Relids relids, List **considered_relids) { IndexClauseSet clauseset; int indexcol; /* If we already considered this relids set, don't repeat the work */ if (bms_equal_any(relids, *considered_relids)) return; /* Identify indexclauses usable with this relids set */ MemSet(&clauseset, 0, sizeof(clauseset)); for (indexcol = 0; indexcol < index->ncolumns; indexcol++) { ListCell *lc; /* First find applicable simple join clauses */ foreach(lc, jclauseset->indexclauses[indexcol]) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); if (bms_is_subset(rinfo->clause_relids, relids)) clauseset.indexclauses[indexcol] = lappend(clauseset.indexclauses[indexcol], rinfo); } /* * 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]) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); if (bms_is_subset(rinfo->clause_relids, relids)) { clauseset.indexclauses[indexcol] = lappend(clauseset.indexclauses[indexcol], rinfo); break; } } /* Add restriction clauses (this is nondestructive to rclauseset) */ 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. We use lcons not * lappend to avoid confusing the loop in consider_index_join_outer_rels. */ *considered_relids = lcons(relids, *considered_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) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); if (rinfo->parent_ec == parent_ec && bms_is_subset(rinfo->clause_relids, oldrelids)) return true; } return false; } /* * bms_equal_any * True if relids is bms_equal to any member of relids_list * * Perhaps this should be in bitmapset.c someday. */ static bool bms_equal_any(Relids relids, List *relids_list) { ListCell *lc; foreach(lc, relids_list) { if (bms_equal(relids, (Relids) lfirst(lc))) return true; } return false; } /* * get_index_paths * Given an index and a set of index clauses for it, construct IndexPaths. * * Plain indexpaths are sent directly to add_path, while potential * bitmap indexpaths are added to *bitindexpaths for later processing. * * This is a fairly simple frontend to build_index_paths(). Its reason for * existence is mainly to handle ScalarArrayOpExpr quals properly. If the * index AM supports them natively, we should just include them in simple * index paths. If not, we should exclude them while building simple index * paths, and then make a separate attempt to include them in bitmap paths. * Furthermore, we should consider excluding lower-order ScalarArrayOpExpr * quals so as to create ordered paths. */ static void get_index_paths(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *clauses, List **bitindexpaths) { List *indexpaths; bool skip_nonnative_saop = false; bool skip_lower_saop = false; ListCell *lc; /* * Build simple index paths using the clauses. Allow ScalarArrayOpExpr * clauses only if the index AM supports them natively, and skip any such * clauses for index columns after the first (so that we produce ordered * paths if possible). */ indexpaths = build_index_paths(root, rel, index, clauses, index->predOK, ST_ANYSCAN, &skip_nonnative_saop, &skip_lower_saop); /* * If we skipped any lower-order ScalarArrayOpExprs on an index with an AM * that supports them, then try again including those clauses. This will * produce paths with more selectivity but no ordering. */ if (skip_lower_saop) { indexpaths = list_concat(indexpaths, build_index_paths(root, rel, index, clauses, index->predOK, ST_ANYSCAN, &skip_nonnative_saop, NULL)); } /* * Submit all the ones that can form plain IndexScan plans to add_path. (A * plain IndexPath can represent either a plain IndexScan or an * IndexOnlyScan, but for our purposes here that distinction does not * matter. However, some of the indexes might support only bitmap scans, * and those we mustn't submit to add_path here.) * * Also, pick out the ones that are usable as bitmap scans. For that, we * must discard indexes that don't support bitmap scans, and we also are * only interested in paths that have some selectivity; we should discard * anything that was generated solely for ordering purposes. */ foreach(lc, indexpaths) { IndexPath *ipath = (IndexPath *) lfirst(lc); if (index->amhasgettuple) add_path(rel, (Path *) ipath); if (index->amhasgetbitmap && (ipath->path.pathkeys == NIL || ipath->indexselectivity < 1.0)) *bitindexpaths = lappend(*bitindexpaths, ipath); } /* * If there were ScalarArrayOpExpr clauses that the index can't handle * natively, generate bitmap scan paths relying on executor-managed * ScalarArrayOpExpr. */ if (skip_nonnative_saop) { indexpaths = build_index_paths(root, rel, index, clauses, false, ST_BITMAPSCAN, NULL, NULL); *bitindexpaths = list_concat(*bitindexpaths, indexpaths); } } /* * build_index_paths * Given an index and a set of index clauses for it, construct zero * or more IndexPaths. * * We return a list of paths because (1) this routine checks some cases * that should cause us to not generate any IndexPath, and (2) in some * cases we want to consider both a forward and a backward scan, so as * to obtain both sort orders. Note that the paths are just returned * to the caller and not immediately fed to add_path(). * * At top level, useful_predicate should be exactly the index's predOK flag * (ie, true if it has a predicate that was proven from the restriction * clauses). When working on an arm of an OR clause, useful_predicate * should be true if the predicate required the current OR list to be proven. * Note that this routine should never be called at all if the index has an * unprovable predicate. * * scantype indicates whether we want to create plain indexscans, bitmap * indexscans, or both. When it's ST_BITMAPSCAN, we will not consider * index ordering while deciding if a Path is worth generating. * * If skip_nonnative_saop is non-NULL, we ignore ScalarArrayOpExpr clauses * unless the index AM supports them directly, and we set *skip_nonnative_saop * to TRUE if we found any such clauses (caller must initialize the variable * to FALSE). If it's NULL, we do not ignore ScalarArrayOpExpr clauses. * * If skip_lower_saop is non-NULL, we ignore ScalarArrayOpExpr clauses for * non-first index columns, and we set *skip_lower_saop to TRUE if we found * any such clauses (caller must initialize the variable to FALSE). If it's * NULL, we do not ignore non-first ScalarArrayOpExpr clauses, but they will * result in considering the scan's output to be unordered. * * 'rel' is the index's heap relation * 'index' is the index for which we want to generate paths * 'clauses' is the collection of indexable clauses (RestrictInfo nodes) * 'useful_predicate' indicates whether the index has a useful predicate * 'scantype' indicates whether we need plain or bitmap scan support * 'skip_nonnative_saop' indicates whether to accept SAOP if index AM doesn't * 'skip_lower_saop' indicates whether to accept non-first-column SAOP */ static List * build_index_paths(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *clauses, bool useful_predicate, ScanTypeControl scantype, bool *skip_nonnative_saop, bool *skip_lower_saop) { List *result = NIL; IndexPath *ipath; List *index_clauses; List *clause_columns; Relids outer_relids; double loop_count; List *orderbyclauses; List *orderbyclausecols; List *index_pathkeys; List *useful_pathkeys; bool found_lower_saop_clause; bool pathkeys_possibly_useful; bool index_is_ordered; bool index_only_scan; int indexcol; /* * Check that index supports the desired scan type(s) */ switch (scantype) { case ST_INDEXSCAN: if (!index->amhasgettuple) return NIL; break; case ST_BITMAPSCAN: if (!index->amhasgetbitmap) return NIL; break; case ST_ANYSCAN: /* either or both are OK */ break; } /* * 1. Collect the index clauses into a single list. * * We build a list of RestrictInfo nodes for clauses to be used with this * index, along with an integer list of the index column numbers (zero * based) that each clause should be used with. The 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 * lists can be empty, if the index AM allows that. * * found_lower_saop_clause is set true if we accept a ScalarArrayOpExpr * index clause for a non-first index column. This prevents us from * assuming that the scan result is ordered. (Actually, the result is * still ordered if there are equality constraints for all earlier * columns, but it seems too expensive and non-modular for this code to be * aware of that refinement.) * * We also build a Relids set showing which outer rels are required by the * selected clauses. Any lateral_relids are included in that, but not * otherwise accounted for. */ index_clauses = NIL; clause_columns = NIL; found_lower_saop_clause = false; outer_relids = bms_copy(rel->lateral_relids); for (indexcol = 0; indexcol < index->ncolumns; indexcol++) { ListCell *lc; foreach(lc, clauses->indexclauses[indexcol]) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); if (IsA(rinfo->clause, ScalarArrayOpExpr)) { if (!index->amsearcharray) { if (skip_nonnative_saop) { /* Ignore because not supported by index */ *skip_nonnative_saop = true; continue; } /* Caller had better intend this only for bitmap scan */ Assert(scantype == ST_BITMAPSCAN); } if (indexcol > 0) { if (skip_lower_saop) { /* Caller doesn't want to lose index ordering */ *skip_lower_saop = true; continue; } found_lower_saop_clause = true; } } index_clauses = lappend(index_clauses, rinfo); clause_columns = lappend_int(clause_columns, indexcol); outer_relids = bms_add_members(outer_relids, rinfo->clause_relids); } /* * If no clauses match the first index column, check for amoptionalkey * restriction. We can't generate a scan over an index with * amoptionalkey = false unless there's at least one index clause. * (When working on columns after the first, this test cannot fail. It * is always okay for columns after the first to not have any * clauses.) */ if (index_clauses == NIL && !index->amoptionalkey) return NIL; } /* We do not want the index's rel itself listed in outer_relids */ outer_relids = bms_del_member(outer_relids, rel->relid); /* Enforce convention that outer_relids is exactly NULL if empty */ if (bms_is_empty(outer_relids)) outer_relids = NULL; /* Compute loop_count for cost estimation purposes */ loop_count = get_loop_count(root, rel->relid, outer_relids); /* * 2. Compute pathkeys describing index's ordering, if any, then see how * many of them are actually useful for this query. This is not relevant * if we are only trying to build bitmap indexscans, nor if we have to * assume the scan is unordered. */ pathkeys_possibly_useful = (scantype != ST_BITMAPSCAN && !found_lower_saop_clause && has_useful_pathkeys(root, rel)); index_is_ordered = (index->sortopfamily != NULL); if (index_is_ordered && pathkeys_possibly_useful) { index_pathkeys = build_index_pathkeys(root, index, ForwardScanDirection); useful_pathkeys = truncate_useless_pathkeys(root, rel, index_pathkeys); orderbyclauses = NIL; orderbyclausecols = NIL; } else if (index->amcanorderbyop && pathkeys_possibly_useful) { /* see if we can generate ordering operators for query_pathkeys */ match_pathkeys_to_index(index, root->query_pathkeys, &orderbyclauses, &orderbyclausecols); if (orderbyclauses) useful_pathkeys = root->query_pathkeys; else useful_pathkeys = NIL; } else { useful_pathkeys = NIL; orderbyclauses = NIL; orderbyclausecols = NIL; } /* * 3. Check if an index-only scan is possible. If we're not building * plain indexscans, this isn't relevant since bitmap scans don't support * index data retrieval anyway. */ index_only_scan = (scantype != ST_BITMAPSCAN && check_index_only(rel, index)); /* * 4. Generate an indexscan path if there are relevant restriction clauses * in the current clauses, OR the index ordering is potentially useful for * later merging or final output ordering, OR the index has a useful * predicate, OR an index-only scan is possible. */ if (index_clauses != NIL || useful_pathkeys != NIL || useful_predicate || index_only_scan) { ipath = create_index_path(root, index, index_clauses, clause_columns, orderbyclauses, orderbyclausecols, useful_pathkeys, index_is_ordered ? ForwardScanDirection : NoMovementScanDirection, index_only_scan, outer_relids, loop_count); result = lappend(result, 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, clause_columns, NIL, NIL, useful_pathkeys, BackwardScanDirection, index_only_scan, outer_relids, loop_count); result = lappend(result, 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(list_copy(clauses), other_clauses); if (!predicate_implied_by(index->indpred, all_clauses)) continue; /* can't use it at all */ if (!predicate_implied_by(index->indpred, other_clauses)) useful_predicate = true; } } /* * Identify the restriction clauses that can match the index. */ MemSet(&clauseset, 0, sizeof(clauseset)); match_clauses_to_index(index, clauses, &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(index, other_clauses, &clauseset); /* * Construct paths if possible. */ indexpaths = build_index_paths(root, rel, index, &clauseset, useful_predicate, ST_BITMAPSCAN, NULL, NULL); result = list_concat(result, indexpaths); } return result; } /* * generate_bitmap_or_paths * Look through the list of clauses to find OR clauses, and generate * a BitmapOrPath for each one we can handle that way. Return a list * of the generated BitmapOrPaths. * * other_clauses is a list of additional clauses that can be assumed true * for the purpose of generating indexquals, but are not to be searched for * ORs. (See build_paths_for_OR() for motivation.) */ static List * generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel, List *clauses, List *other_clauses) { List *result = NIL; List *all_clauses; ListCell *lc; /* * We can use both the current and other clauses as context for * build_paths_for_OR; no need to remove ORs from the lists. */ all_clauses = list_concat(list_copy(clauses), other_clauses); foreach(lc, clauses) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); List *pathlist; Path *bitmapqual; ListCell *j; Assert(IsA(rinfo, RestrictInfo)); /* Ignore RestrictInfos that aren't ORs */ if (!restriction_is_or_clause(rinfo)) continue; /* * We must be able to match at least one index to each of the arms of * the OR, else we can't use it. */ pathlist = NIL; foreach(j, ((BoolExpr *) rinfo->orclause)->args) { Node *orarg = (Node *) lfirst(j); List *indlist; /* OR arguments should be ANDs or sub-RestrictInfos */ if (and_clause(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 { List *orargs; Assert(IsA(orarg, RestrictInfo)); Assert(!restriction_is_or_clause((RestrictInfo *) orarg)); orargs = list_make1(orarg); indlist = build_paths_for_OR(root, rel, orargs, all_clauses); } /* * If nothing matched this arm, we can't do anything with this OR * clause. */ if (indlist == NIL) { pathlist = NIL; break; } /* * OK, pick the most promising AND combination, and add it to * pathlist. */ bitmapqual = choose_bitmap_and(root, rel, indlist); pathlist = lappend(pathlist, bitmapqual); } /* * If we have a match for every arm, then turn them into a * BitmapOrPath, and add to result list. */ if (pathlist != NIL) { bitmapqual = (Path *) create_bitmap_or_path(root, rel, pathlist); result = lappend(result, bitmapqual); } } return result; } /* * choose_bitmap_and * Given a nonempty list of bitmap paths, AND them into one path. * * This is a nontrivial decision since we can legally use any subset of the * given path set. We want to choose a good tradeoff between selectivity * and cost of computing the bitmap. * * The result is either a single one of the inputs, or a BitmapAndPath * combining multiple inputs. */ static Path * choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel, List *paths) { int npaths = list_length(paths); PathClauseUsage **pathinfoarray; PathClauseUsage *pathinfo; List *clauselist; List *bestpaths = NIL; Cost bestcost = 0; int i, j; ListCell *l; Assert(npaths > 0); /* else caller error */ if (npaths == 1) return (Path *) linitial(paths); /* easy case */ /* * In theory we should consider every nonempty subset of the given paths. * In practice that seems like overkill, given the crude nature of the * estimates, not to mention the possible effects of higher-level AND and * OR clauses. Moreover, it's completely impractical if there are a large * number of paths, since the work would grow as O(2^N). * * As a heuristic, we first check for paths using exactly the same sets of * WHERE clauses + index predicate conditions, and reject all but the * cheapest-to-scan in any such group. This primarily gets rid of indexes * that include the interesting columns but also irrelevant columns. (In * situations where the DBA has gone overboard on creating variant * indexes, this can make for a very large reduction in the number of * paths considered further.) * * We then sort the surviving paths with the cheapest-to-scan first, and * for each path, consider using that path alone as the basis for a bitmap * scan. Then we consider bitmap AND scans formed from that path plus * each subsequent (higher-cost) path, adding on a subsequent path if it * results in a reduction in the estimated total scan cost. This means we * consider about O(N^2) rather than O(2^N) path combinations, which is * quite tolerable, especially given than N is usually reasonably small * because of the prefiltering step. The cheapest of these is returned. * * We will only consider AND combinations in which no two indexes use the * same WHERE clause. This is a bit of a kluge: it's needed because * costsize.c and clausesel.c aren't very smart about redundant clauses. * They will usually double-count the redundant clauses, producing a * too-small selectivity that makes a redundant AND step look like it * reduces the total cost. Perhaps someday that code will be smarter and * we can remove this limitation. (But note that this also defends * against flat-out duplicate input paths, which can happen because * match_join_clauses_to_index will find the same OR join clauses that * extract_restriction_or_clauses has pulled OR restriction clauses out * of.) * * For the same reason, we reject AND combinations in which an index * predicate clause duplicates another clause. Here we find it necessary * to be even stricter: we'll reject a partial index if any of its * predicate clauses are implied by the set of WHERE clauses and predicate * clauses used so far. This covers cases such as a condition "x = 42" * used with a plain index, followed by a clauseless scan of a partial * index "WHERE x >= 40 AND x < 50". The partial index has been accepted * only because "x = 42" was present, and so allowing it would partially * double-count selectivity. (We could use predicate_implied_by on * regular qual clauses too, to have a more intelligent, but much more * expensive, check for redundancy --- but in most cases simple equality * seems to suffice.) */ /* * Extract clause usage info and detect any paths that use exactly the * same set of clauses; keep only the cheapest-to-scan of any such groups. * The surviving paths are put into an array for qsort'ing. */ pathinfoarray = (PathClauseUsage **) palloc(npaths * sizeof(PathClauseUsage *)); clauselist = NIL; npaths = 0; foreach(l, paths) { Path *ipath = (Path *) lfirst(l); pathinfo = classify_index_clause_usage(ipath, &clauselist); for (i = 0; i < npaths; i++) { if (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. */ for (i = 0; i < npaths; i++) { Cost costsofar; List *qualsofar; Bitmapset *clauseidsofar; ListCell *lastcell; pathinfo = pathinfoarray[i]; paths = list_make1(pathinfo->path); costsofar = bitmap_scan_cost_est(root, rel, pathinfo->path); qualsofar = list_concat(list_copy(pathinfo->quals), list_copy(pathinfo->preds)); clauseidsofar = bms_copy(pathinfo->clauseids); lastcell = list_head(paths); /* for quick deletions */ 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)) { 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, list_copy(pathinfo->quals)); qualsofar = list_concat(qualsofar, list_copy(pathinfo->preds)); clauseidsofar = bms_add_members(clauseidsofar, pathinfo->clauseids); lastcell = lnext(lastcell); } else { /* reject new path, remove it from paths list */ paths = list_delete_cell(paths, lnext(lastcell), lastcell); } Assert(lnext(lastcell) == NULL); } /* 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 (no BitmapAnd, at least not at this level; but it could be * a BitmapOr). */ static Cost bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath) { BitmapHeapPath bpath; Relids required_outer; /* Identify required outer rels, in case it's a parameterized scan */ required_outer = get_bitmap_tree_required_outer(ipath); /* Set up a dummy BitmapHeapPath */ bpath.path.type = T_BitmapHeapPath; bpath.path.pathtype = T_BitmapHeapScan; bpath.path.parent = rel; bpath.path.param_info = get_baserel_parampathinfo(root, rel, required_outer); bpath.path.pathkeys = NIL; bpath.bitmapqual = ipath; cost_bitmap_heap_scan(&bpath.path, root, rel, bpath.path.param_info, ipath, get_loop_count(root, rel->relid, required_outer)); 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; BitmapHeapPath bpath; Relids required_outer; /* Set up a dummy BitmapAndPath */ apath.path.type = T_BitmapAndPath; apath.path.pathtype = T_BitmapAnd; apath.path.parent = rel; apath.path.param_info = NULL; /* not used in bitmap trees */ apath.path.pathkeys = NIL; apath.bitmapquals = paths; cost_bitmap_and_node(&apath, root); /* Identify required outer rels, in case it's a parameterized scan */ required_outer = get_bitmap_tree_required_outer((Path *) &apath); /* Set up a dummy BitmapHeapPath */ bpath.path.type = T_BitmapHeapPath; bpath.path.pathtype = T_BitmapHeapScan; bpath.path.parent = rel; bpath.path.param_info = get_baserel_parampathinfo(root, rel, required_outer); bpath.path.pathkeys = NIL; bpath.bitmapqual = (Path *) &apath; /* Now we can do cost_bitmap_heap_scan */ cost_bitmap_heap_scan(&bpath.path, root, rel, bpath.path.param_info, (Path *) &apath, get_loop_count(root, rel->relid, required_outer)); return bpath.path.total_cost; } /* * 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); /* 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; return result; } /* * get_bitmap_tree_required_outer * Find the required outer rels for a bitmap tree (index/and/or) * * We don't associate any particular parameterization with a BitmapAnd or * BitmapOr node; however, the IndexPaths have parameterization info, in * their capacity as standalone access paths. The parameterization required * for the bitmap heap scan node is the union of rels referenced in the * child IndexPaths. */ static Relids get_bitmap_tree_required_outer(Path *bitmapqual) { Relids result = NULL; ListCell *lc; if (IsA(bitmapqual, IndexPath)) { return bms_copy(PATH_REQ_OUTER(bitmapqual)); } else if (IsA(bitmapqual, BitmapAndPath)) { foreach(lc, ((BitmapAndPath *) bitmapqual)->bitmapquals) { result = bms_join(result, get_bitmap_tree_required_outer((Path *) lfirst(lc))); } } else if (IsA(bitmapqual, BitmapOrPath)) { foreach(lc, ((BitmapOrPath *) bitmapqual)->bitmapquals) { result = bms_join(result, get_bitmap_tree_required_outer((Path *) lfirst(lc))); } } else elog(ERROR, "unrecognized node type: %d", nodeTag(bitmapqual)); return result; } /* * find_indexpath_quals * * Given the Path structure for a plain or bitmap indexscan, extract lists * of all the indexquals 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; *quals = list_concat(*quals, get_actual_clauses(ipath->indexclauses)); *preds = list_concat(*preds, list_copy(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. * * XXX this is overly conservative for partial indexes, since we will * consider attributes involved in the index predicate as required even * though the predicate won't need to be checked at runtime. (The same is * true for attributes used only in index quals, if we are certain that * the index is not lossy.) However, it would be quite expensive to * determine that accurately at this point, so for now we take the easy * way out. */ /* * Add all the attributes needed for joins or final output. Note: we must * look at reltargetlist, not the attr_needed data, because attr_needed * isn't computed for inheritance child rels. */ pull_varattnos((Node *) rel->reltargetlist, rel->relid, &attrs_used); /* Add all the attributes used by restriction clauses. */ foreach(lc, rel->baserestrictinfo) { 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); 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(RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *clauseset) { match_clauses_to_index(index, rel->baserestrictinfo, clauseset); } /* * match_join_clauses_to_index * Identify join clauses for the rel that match the index. * Matching clauses are added to *clauseset. * Also, add any potentially usable join OR clauses to *joinorclauses. */ static void match_join_clauses_to_index(PlannerInfo *root, RelOptInfo *rel, IndexOptInfo *index, IndexClauseSet *clauseset, List **joinorclauses) { ListCell *lc; /* Scan the rel's join clauses */ foreach(lc, rel->joininfo) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); /* Check if clause can be moved to this rel */ if (!join_clause_is_movable_to(rinfo, rel)) continue; /* Potentially usable, so see if it matches the index or is an OR */ if (restriction_is_or_clause(rinfo)) *joinorclauses = lappend(*joinorclauses, rinfo); else match_clause_to_index(index, rinfo, 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->ncolumns; indexcol++) { ec_member_matches_arg arg; List *clauses; /* Generate clauses, skipping any that join to lateral_referencers */ arg.index = index; arg.indexcol = indexcol; clauses = generate_implied_equalities_for_column(root, index->rel, ec_member_matches_indexcol, (void *) &arg, index->rel->lateral_referencers); /* * We have to check whether the results actually do match the index, * since for non-btree indexes the EC's equality operators might not * be in the index opclass (cf ec_member_matches_indexcol). */ match_clauses_to_index(index, clauses, 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(IndexOptInfo *index, List *clauses, IndexClauseSet *clauseset) { ListCell *lc; foreach(lc, clauses) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); Assert(IsA(rinfo, RestrictInfo)); match_clause_to_index(index, rinfo, clauseset); } } /* * match_clause_to_index * Test whether a qual clause can be used with an index. * * If the clause is usable, add 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(IndexOptInfo *index, RestrictInfo *rinfo, IndexClauseSet *clauseset) { int indexcol; for (indexcol = 0; indexcol < index->ncolumns; indexcol++) { if (match_clause_to_indexcol(index, indexcol, rinfo)) { clauseset->indexclauses[indexcol] = list_append_unique_ptr(clauseset->indexclauses[indexcol], rinfo); clauseset->nonempty = true; return; } } } /* * match_clause_to_indexcol() * Determines whether a restriction clause matches a column of an index. * * To match an index normally, the clause: * * (1) must be in the form (indexkey op const) or (const op indexkey); * and * (2) must contain an operator which is in the same family as the index * operator for this column, or is a "special" operator as recognized * by match_special_index_operator(); * 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 do not actually do the commuting here, but we check whether a * suitable commutator operator is available. * * 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). In this routine we will * report a match if 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 --- whether the * remaining columns match the index too is considered in * adjust_rowcompare_for_index(). * * It is also possible to match ScalarArrayOpExpr clauses to indexes, when * the clause is of the form "indexkey op ANY (arrayconst)". * * For boolean indexes, it is also possible to match the clause directly * to the indexkey; or perhaps the clause is (NOT indexkey). * * 'index' is the index of interest. * 'indexcol' is a column number of 'index' (counting from 0). * 'rinfo' is the clause to be tested (as a RestrictInfo node). * * Returns true if the clause can be used with this index key. * * NOTE: returns false if clause is an OR or AND clause; it is the * responsibility of higher-level routines to cope with those. */ static bool match_clause_to_indexcol(IndexOptInfo *index, int indexcol, RestrictInfo *rinfo) { Expr *clause = rinfo->clause; Index index_relid = index->rel->relid; Oid opfamily = index->opfamily[indexcol]; Oid idxcollation = index->indexcollations[indexcol]; Node *leftop, *rightop; Relids left_relids; Relids right_relids; Oid expr_op; Oid expr_coll; bool plain_op; /* * Never match pseudoconstants to indexes. (Normally this 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 false; /* First check for boolean-index cases. */ if (IsBooleanOpfamily(opfamily)) { if (match_boolean_index_clause((Node *) clause, indexcol, index)) return true; } /* * Clause must be a binary opclause, or possibly a ScalarArrayOpExpr * (which is always binary, by definition). Or it could be a * RowCompareExpr, which we pass off to match_rowcompare_to_indexcol(). * Or, if the index supports it, we can handle IS NULL/NOT NULL clauses. */ if (is_opclause(clause)) { leftop = get_leftop(clause); rightop = get_rightop(clause); if (!leftop || !rightop) return false; left_relids = rinfo->left_relids; right_relids = rinfo->right_relids; expr_op = ((OpExpr *) clause)->opno; expr_coll = ((OpExpr *) clause)->inputcollid; plain_op = true; } else if (clause && IsA(clause, ScalarArrayOpExpr)) { ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) clause; /* We only accept ANY clauses, not ALL */ if (!saop->useOr) return false; leftop = (Node *) linitial(saop->args); rightop = (Node *) lsecond(saop->args); left_relids = NULL; /* not actually needed */ right_relids = pull_varnos(rightop); expr_op = saop->opno; expr_coll = saop->inputcollid; plain_op = false; } else if (clause && IsA(clause, RowCompareExpr)) { return match_rowcompare_to_indexcol(index, indexcol, opfamily, idxcollation, (RowCompareExpr *) clause); } else if (index->amsearchnulls && IsA(clause, NullTest)) { NullTest *nt = (NullTest *) clause; if (!nt->argisrow && match_index_to_operand((Node *) nt->arg, indexcol, index)) return true; return false; } else return false; /* * Check for clauses of the form: (indexkey operator constant) or * (constant operator indexkey). See above notes about const-ness. */ if (match_index_to_operand(leftop, indexcol, index) && !bms_is_member(index_relid, right_relids) && !contain_volatile_functions(rightop)) { if (IndexCollMatchesExprColl(idxcollation, expr_coll) && is_indexable_operator(expr_op, opfamily, true)) return true; /* * If we didn't find a member of the index's opfamily, see whether it * is a "special" indexable operator. */ if (plain_op && match_special_index_operator(clause, opfamily, idxcollation, true)) return true; return false; } if (plain_op && match_index_to_operand(rightop, indexcol, index) && !bms_is_member(index_relid, left_relids) && !contain_volatile_functions(leftop)) { if (IndexCollMatchesExprColl(idxcollation, expr_coll) && is_indexable_operator(expr_op, opfamily, false)) return true; /* * If we didn't find a member of the index's opfamily, see whether it * is a "special" indexable operator. */ if (match_special_index_operator(clause, opfamily, idxcollation, false)) return true; return false; } return false; } /* * is_indexable_operator * Does the operator match the specified index opfamily? * * If the indexkey is on the right, what we actually want to know * is whether the operator has a commutator operator that matches * the opfamily. */ static bool is_indexable_operator(Oid expr_op, Oid opfamily, bool indexkey_on_left) { /* Get the commuted operator if necessary */ if (!indexkey_on_left) { expr_op = get_commutator(expr_op); if (expr_op == InvalidOid) return false; } /* OK if the (commuted) operator is a member of the index's opfamily */ return op_in_opfamily(expr_op, opfamily); } /* * match_rowcompare_to_indexcol() * Handles the RowCompareExpr case for match_clause_to_indexcol(), * which see for comments. */ static bool match_rowcompare_to_indexcol(IndexOptInfo *index, int indexcol, Oid opfamily, Oid idxcollation, RowCompareExpr *clause) { Index index_relid = index->rel->relid; Node *leftop, *rightop; Oid expr_op; Oid expr_coll; /* Forget it if we're not dealing with a btree index */ if (index->relam != BTREE_AM_OID) return false; /* * 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 false; /* * These syntactic tests are the same as in match_clause_to_indexcol() */ if (match_index_to_operand(leftop, indexcol, index) && !bms_is_member(index_relid, pull_varnos(rightop)) && !contain_volatile_functions(rightop)) { /* OK, indexkey is on left */ } else if (match_index_to_operand(rightop, indexcol, index) && !bms_is_member(index_relid, pull_varnos(leftop)) && !contain_volatile_functions(leftop)) { /* indexkey is on right, so commute the operator */ expr_op = get_commutator(expr_op); if (expr_op == InvalidOid) return false; } else return false; /* 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 true; } return false; } /**************************************************************************** * ---- ROUTINES TO CHECK ORDERING OPERATORS ---- ****************************************************************************/ /* * match_pathkeys_to_index * Test whether an index can produce output ordered according to the * given pathkeys using "ordering operators". * * If it can, return a list of suitable ORDER BY expressions, each of the form * "indexedcol operator pseudoconstant", along with an integer list of the * index column numbers (zero based) that each clause would be used with. * NIL lists are returned if the ordering is not achievable this way. * * On success, the result list is ordered by pathkeys, and in fact is * one-to-one with the requested pathkeys. */ static void match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys, List **orderby_clauses_p, List **clause_columns_p) { List *orderby_clauses = NIL; List *clause_columns = NIL; ListCell *lc1; *orderby_clauses_p = NIL; /* set default results */ *clause_columns_p = NIL; /* Only indexes with the amcanorderbyop property are interesting here */ if (!index->amcanorderbyop) return; foreach(lc1, pathkeys) { PathKey *pathkey = (PathKey *) lfirst(lc1); bool found = false; ListCell *lc2; /* * Note: for any failure to match, we just return NIL immediately. * There is no value in matching just some of the pathkeys. */ /* Pathkey must request default sort order for the target opfamily */ if (pathkey->pk_strategy != BTLessStrategyNumber || pathkey->pk_nulls_first) return; /* If eclass is volatile, no hope of using an indexscan */ if (pathkey->pk_eclass->ec_has_volatile) return; /* * Try to match eclass member expression(s) to index. Note that child * EC members are considered, but only when they belong to the target * relation. (Unlike regular members, the same expression could be a * child member of more than one EC. Therefore, the same index could * be considered to match more than one pathkey list, which is OK * here. See also get_eclass_for_sort_expr.) */ foreach(lc2, pathkey->pk_eclass->ec_members) { EquivalenceMember *member = (EquivalenceMember *) lfirst(lc2); int indexcol; /* No possibility of match if it references other relations */ if (!bms_equal(member->em_relids, index->rel->relids)) continue; /* * We allow any column of the index to match each pathkey; they * don't have to match left-to-right as you might expect. This is * correct for GiST, which is the sole existing AM supporting * amcanorderbyop. We might need different logic in future for * other implementations. */ for (indexcol = 0; indexcol < index->ncolumns; indexcol++) { Expr *expr; expr = match_clause_to_ordering_op(index, indexcol, member->em_expr, pathkey->pk_opfamily); if (expr) { orderby_clauses = lappend(orderby_clauses, expr); clause_columns = lappend_int(clause_columns, indexcol); found = true; break; } } if (found) /* don't want to look at remaining members */ break; } if (!found) /* fail if no match for this pathkey */ return; } *orderby_clauses_p = orderby_clauses; /* success! */ *clause_columns_p = clause_columns; } /* * match_clause_to_ordering_op * Determines whether an ordering operator expression matches an * index column. * * This is similar to, but simpler than, match_clause_to_indexcol. * We only care about simple OpExpr cases. The input is a bare * expression that is being ordered by, which must be of the form * (indexkey op const) or (const op indexkey) where op is an ordering * operator for the column's opfamily. * * 'index' is the index of interest. * 'indexcol' is a column number of 'index' (counting from 0). * 'clause' is the ordering expression to be tested. * 'pk_opfamily' is the btree opfamily describing the required sort order. * * Note that we currently do not consider the collation of the ordering * operator's result. In practical cases the result type will be numeric * and thus have no collation, and it's not very clear what to match to * if it did have a collation. The index's collation should match the * ordering operator's input collation, not its result. * * If successful, return 'clause' as-is if the indexkey is on the left, * otherwise a commuted copy of 'clause'. If no match, return NULL. */ static Expr * match_clause_to_ordering_op(IndexOptInfo *index, int indexcol, Expr *clause, Oid pk_opfamily) { Oid opfamily = index->opfamily[indexcol]; Oid idxcollation = index->indexcollations[indexcol]; Node *leftop, *rightop; Oid expr_op; Oid expr_coll; Oid sortfamily; bool commuted; /* * 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_partial_indexes * Check each partial index of the relation, and mark it predOK if * the index's predicate is satisfied for this query. * * Note: it is possible for this to get re-run after adding more restrictions * to the rel; so we might be able to prove more indexes OK. We assume that * adding more restrictions can't make an index not OK. */ void check_partial_indexes(PlannerInfo *root, RelOptInfo *rel) { List *clauselist; bool have_partial; Relids otherrels; ListCell *lc; /* * Frequently, there will be no partial indexes, so first check to make * sure there's something useful to do here. */ have_partial = false; foreach(lc, rel->indexlist) { IndexOptInfo *index = (IndexOptInfo *) lfirst(lc); if (index->indpred == NIL) continue; /* ignore non-partial indexes */ if (index->predOK) continue; /* don't repeat work if already proven OK */ have_partial = true; break; } if (!have_partial) return; /* * Construct a list of clauses that we can assume true for the purpose of * proving the index(es) usable. Restriction clauses for the rel are * always usable, and so are any join clauses that are "movable to" this * rel. Also, we can consider any EC-derivable join clauses (which must * be "movable to" this rel, by definition). */ clauselist = list_copy(rel->baserestrictinfo); /* Scan the rel's join clauses */ foreach(lc, rel->joininfo) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); /* Check if clause can be moved to this rel */ if (!join_clause_is_movable_to(rinfo, rel)) continue; clauselist = lappend(clauselist, rinfo); } /* * Add on any equivalence-derivable join clauses. Computing the correct * relid sets for generate_join_implied_equalities is slightly tricky * because the rel could be a child rel rather than a true baserel, and in * that case we must remove its parents' relid(s) from all_baserels. */ if (rel->reloptkind == RELOPT_OTHER_MEMBER_REL) otherrels = bms_difference(root->all_baserels, find_childrel_parents(root, rel)); else otherrels = bms_difference(root->all_baserels, rel->relids); if (!bms_is_empty(otherrels)) clauselist = list_concat(clauselist, generate_join_implied_equalities(root, bms_union(rel->relids, otherrels), otherrels, rel)); /* Now try to prove each index predicate true */ foreach(lc, rel->indexlist) { IndexOptInfo *index = (IndexOptInfo *) lfirst(lc); if (index->indpred == NIL) continue; /* ignore non-partial indexes */ if (index->predOK) continue; /* don't repeat work if already proven OK */ index->predOK = predicate_implied_by(index->indpred, clauselist); } } /**************************************************************************** * ---- 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 = index->opfamily[indexcol]; Oid curCollation = index->indexcollations[indexcol]; /* * If it's a btree index, we can reject it if its opfamily isn't * compatible with the EC, since no clause generated from the EC could be * used with the index. For non-btree indexes, we can't easily tell * whether clauses generated from the EC could be used with the index, so * don't check the opfamily. This might mean we return "true" for a * useless EC, so we have to recheck the results of * generate_implied_equalities_for_column; see * match_eclass_clauses_to_index. */ if (index->relam == BTREE_AM_OID && !list_member_oid(ec->ec_opfamilies, curFamily)) return false; /* We insist on collation match for all index types, though */ if (!IndexCollMatchesExprColl(curCollation, ec->ec_collation)) return false; return match_index_to_operand((Node *) em->em_expr, indexcol, index); } /* * relation_has_unique_index_for * Determine whether the relation provably has at most one row satisfying * a set of equality conditions, because the conditions constrain all * columns of some unique index. * * The conditions can be represented in either or both of two ways: * 1. A list of RestrictInfo nodes, where the caller has already determined * that each condition is a mergejoinable equality with an expression in * this relation on one side, and an expression not involving this relation * on the other. The transient outer_is_left flag is used to identify which * side we should look at: left side if outer_is_left is false, right side * if it is true. * 2. A list of expressions in this relation, and a corresponding list of * equality operators. The caller must have already checked that the operators * represent equality. (Note: the operators could be cross-type; the * expressions should correspond to their RHS inputs.) * * The caller need only supply equality conditions arising from joins; * this routine automatically adds in any usable baserestrictinfo clauses. * (Note that the passed-in restrictlist will be destructively modified!) */ bool relation_has_unique_index_for(PlannerInfo *root, RelOptInfo *rel, List *restrictlist, List *exprlist, List *oprlist) { ListCell *ic; Assert(list_length(exprlist) == list_length(oprlist)); /* Short-circuit if no indexes... */ if (rel->indexlist == NIL) return false; /* * Examine the rel's restriction clauses for usable var = const clauses * that we can add to the restrictlist. */ foreach(ic, rel->baserestrictinfo) { RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(ic); /* * Note: can_join won't be set for a restriction clause, but * mergeopfamilies will be if it has a mergejoinable operator and * doesn't contain volatile functions. */ if (restrictinfo->mergeopfamilies == NIL) continue; /* not mergejoinable */ /* * The clause certainly doesn't refer to anything but the given rel. * If either side is pseudoconstant then we can use it. */ if (bms_is_empty(restrictinfo->left_relids)) { /* righthand side is inner */ restrictinfo->outer_is_left = true; } else if (bms_is_empty(restrictinfo->right_relids)) { /* lefthand side is inner */ restrictinfo->outer_is_left = false; } else continue; /* OK, add to list */ restrictlist = lappend(restrictlist, restrictinfo); } /* Short-circuit the easy case */ if (restrictlist == NIL && exprlist == NIL) return false; /* Examine each index of the relation ... */ foreach(ic, rel->indexlist) { IndexOptInfo *ind = (IndexOptInfo *) lfirst(ic); int c; /* * If the index is not unique, or not immediately enforced, or if it's * a partial index that doesn't match the query, it's useless here. */ if (!ind->unique || !ind->immediate || (ind->indpred != NIL && !ind->predOK)) 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->ncolumns; c++) { bool matched = false; ListCell *lc; ListCell *lc2; foreach(lc, restrictlist) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); Node *rexpr; /* * The condition's equality operator must be a member of the * index opfamily, else it is not asserting the right kind of * equality behavior for this index. We check this first * since it's probably cheaper than match_index_to_operand(). */ if (!list_member_oid(rinfo->mergeopfamilies, ind->opfamily[c])) continue; /* * XXX at some point we may need to check collations here too. * For the moment we assume all collations reduce to the same * notion of equality. */ /* OK, see if the condition operand matches the index key */ if (rinfo->outer_is_left) rexpr = get_rightop(rinfo->clause); else rexpr = get_leftop(rinfo->clause); if (match_index_to_operand(rexpr, c, ind)) { matched = true; /* column is unique */ break; } } if (matched) continue; forboth(lc, exprlist, lc2, oprlist) { Node *expr = (Node *) lfirst(lc); Oid opr = lfirst_oid(lc2); /* See if the expression matches the index key */ if (!match_index_to_operand(expr, c, ind)) continue; /* * The equality operator must be a member of the index * opfamily, else it is not asserting the right kind of * equality behavior for this index. We assume the caller * determined it is an equality operator, so we don't need to * check any more tightly than this. */ if (!op_in_opfamily(opr, ind->opfamily[c])) continue; /* * XXX at some point we may need to check collations here too. * For the moment we assume all collations reduce to the same * notion of equality. */ matched = true; /* column is unique */ break; } if (!matched) break; /* no match; this index doesn't help us */ } /* Matched all columns of this index? */ if (c == ind->ncolumns) return true; } return false; } /**************************************************************************** * ---- ROUTINES TO CHECK OPERANDS ---- ****************************************************************************/ /* * match_index_to_operand() * Generalized test for a match between an index's key * and the operand on one side of a restriction or join clause. * * operand: the nodetree to be compared to the index * indexcol: the column number of the index (counting from 0) * index: the index of interest * * Note that we aren't interested in collations here; the caller must check * for a collation match, if it's dealing with an operator where that matters. * * This is exported for use in selfuncs.c. */ bool match_index_to_operand(Node *operand, int indexcol, IndexOptInfo *index) { int indkey; /* * Ignore any RelabelType node above the operand. This is needed to be * able to apply indexscanning in binary-compatible-operator cases. Note: * we can assume there is at most one RelabelType node; * eval_const_expressions() will have simplified if more than one. */ if (operand && IsA(operand, RelabelType)) operand = (Node *) ((RelabelType *) operand)->arg; indkey = index->indexkeys[indexcol]; if (indkey != 0) { /* * Simple index column; operand must be a matching Var. */ if (operand && IsA(operand, Var) && index->rel->relid == ((Var *) operand)->varno && indkey == ((Var *) operand)->varattno) return true; } else { /* * Index expression; find the correct expression. (This search could * be avoided, at the cost of complicating all the callers of this * routine; doesn't seem worth it.) */ ListCell *indexpr_item; int i; Node *indexkey; indexpr_item = list_head(index->indexprs); for (i = 0; i < indexcol; i++) { if (index->indexkeys[i] == 0) { if (indexpr_item == NULL) elog(ERROR, "wrong number of index expressions"); indexpr_item = lnext(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; } /**************************************************************************** * ---- ROUTINES FOR "SPECIAL" INDEXABLE OPERATORS ---- ****************************************************************************/ /* * These routines handle special optimization of operators that can be * used with index scans even though they are not known to the executor's * indexscan machinery. The key idea is that these operators allow us * to derive approximate indexscan qual clauses, such that any tuples * that pass the operator clause itself must also satisfy the simpler * indexscan condition(s). Then we can use the indexscan machinery * to avoid scanning as much of the table as we'd otherwise have to, * while applying the original operator as a qpqual condition to ensure * we deliver only the tuples we want. (In essence, we're using a regular * index as if it were a lossy index.) * * An example of what we're doing is * textfield LIKE 'abc%' * from which we can generate the indexscanable conditions * textfield >= 'abc' AND textfield < 'abd' * which allow efficient scanning of an index on textfield. * (In reality, character set and collation issues make the transformation * from LIKE to indexscan limits rather harder than one might think ... * but that's the basic idea.) * * Another thing that we do with this machinery is to provide special * smarts for "boolean" indexes (that is, indexes on boolean columns * that support boolean equality). We can transform a plain reference * to the indexkey into "indexkey = true", or "NOT indexkey" into * "indexkey = false", so as to make the expression indexable using the * regular index operators. (As of Postgres 8.1, we must do this here * because constant simplification does the reverse transformation; * without this code there'd be no way to use such an index at all.) * * Three routines are provided here: * * match_special_index_operator() is just an auxiliary function for * match_clause_to_indexcol(); after the latter fails to recognize a * restriction opclause's operator as a member of an index's opfamily, * it asks match_special_index_operator() whether the clause should be * considered an indexqual anyway. * * match_boolean_index_clause() similarly detects clauses that can be * converted into boolean equality operators. * * expand_indexqual_conditions() converts a list of RestrictInfo nodes * (with implicit AND semantics across list elements) into a list of clauses * that the executor can actually handle. For operators that are members of * the index's opfamily this transformation is a no-op, but clauses recognized * by match_special_index_operator() or match_boolean_index_clause() must be * converted into one or more "regular" indexqual conditions. */ /* * match_boolean_index_clause * Recognize restriction clauses that can be matched to a boolean index. * * 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. */ static bool match_boolean_index_clause(Node *clause, int indexcol, IndexOptInfo *index) { /* Direct match? */ if (match_index_to_operand(clause, indexcol, index)) return true; /* NOT clause? */ if (not_clause(clause)) { if (match_index_to_operand((Node *) get_notclausearg((Expr *) clause), indexcol, index)) return true; } /* * 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; if (btest->booltesttype == IS_TRUE || btest->booltesttype == IS_FALSE) if (match_index_to_operand((Node *) btest->arg, indexcol, index)) return true; } return false; } /* * match_special_index_operator * Recognize restriction clauses that can be used to generate * additional indexscanable qualifications. * * The given clause is already known to be a binary opclause having * the form (indexkey OP pseudoconst) or (pseudoconst OP indexkey), * but the OP proved not to be one of the index's opfamily operators. * Return 'true' if we can do something with it anyway. */ static bool match_special_index_operator(Expr *clause, Oid opfamily, Oid idxcollation, bool indexkey_on_left) { bool isIndexable = false; Node *rightop; Oid expr_op; Oid expr_coll; Const *patt; Const *prefix = NULL; Pattern_Prefix_Status pstatus = Pattern_Prefix_None; /* * Currently, all known special operators require the indexkey on the * left, but this test could be pushed into the switch statement if some * are added that do not... */ if (!indexkey_on_left) return false; /* we know these will succeed */ rightop = get_rightop(clause); expr_op = ((OpExpr *) clause)->opno; expr_coll = ((OpExpr *) clause)->inputcollid; /* again, required for all current special ops: */ if (!IsA(rightop, Const) || ((Const *) rightop)->constisnull) return false; patt = (Const *) rightop; switch (expr_op) { case OID_TEXT_LIKE_OP: case OID_BPCHAR_LIKE_OP: case OID_NAME_LIKE_OP: /* the right-hand const is type text for all of these */ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like, expr_coll, &prefix, NULL); isIndexable = (pstatus != Pattern_Prefix_None); break; case OID_BYTEA_LIKE_OP: pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like, expr_coll, &prefix, NULL); isIndexable = (pstatus != Pattern_Prefix_None); break; case OID_TEXT_ICLIKE_OP: case OID_BPCHAR_ICLIKE_OP: case OID_NAME_ICLIKE_OP: /* the right-hand const is type text for all of these */ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like_IC, expr_coll, &prefix, NULL); isIndexable = (pstatus != Pattern_Prefix_None); break; case OID_TEXT_REGEXEQ_OP: case OID_BPCHAR_REGEXEQ_OP: case OID_NAME_REGEXEQ_OP: /* the right-hand const is type text for all of these */ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex, expr_coll, &prefix, NULL); isIndexable = (pstatus != Pattern_Prefix_None); break; case OID_TEXT_ICREGEXEQ_OP: case OID_BPCHAR_ICREGEXEQ_OP: case OID_NAME_ICREGEXEQ_OP: /* the right-hand const is type text for all of these */ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex_IC, expr_coll, &prefix, NULL); isIndexable = (pstatus != Pattern_Prefix_None); break; case OID_INET_SUB_OP: case OID_INET_SUBEQ_OP: isIndexable = true; break; } if (prefix) { pfree(DatumGetPointer(prefix->constvalue)); pfree(prefix); } /* done if the expression doesn't look indexable */ if (!isIndexable) return false; /* * Must also check that index's opfamily supports the operators we will * want to apply. (A hash index, for example, will not support ">=".) * Currently, only btree and spgist support the operators we need. * * Note: actually, in the Pattern_Prefix_Exact case, we only need "=" so a * hash index would work. Currently it doesn't seem worth checking for * that, however. * * We insist on the opfamily being the specific one we expect, else we'd * do the wrong thing if someone were to make a reverse-sort opfamily with * the same operators. * * The non-pattern opclasses will not sort the way we need in most non-C * locales. We can use such an index anyway for an exact match (simple * equality), but not for prefix-match cases. Note that here we are * looking at the index's collation, not the expression's collation -- * this test is *not* dependent on the LIKE/regex operator's collation. */ switch (expr_op) { case OID_TEXT_LIKE_OP: case OID_TEXT_ICLIKE_OP: case OID_TEXT_REGEXEQ_OP: case OID_TEXT_ICREGEXEQ_OP: isIndexable = (opfamily == TEXT_PATTERN_BTREE_FAM_OID) || (opfamily == TEXT_SPGIST_FAM_OID) || (opfamily == TEXT_BTREE_FAM_OID && (pstatus == Pattern_Prefix_Exact || lc_collate_is_c(idxcollation))); break; case OID_BPCHAR_LIKE_OP: case OID_BPCHAR_ICLIKE_OP: case OID_BPCHAR_REGEXEQ_OP: case OID_BPCHAR_ICREGEXEQ_OP: isIndexable = (opfamily == BPCHAR_PATTERN_BTREE_FAM_OID) || (opfamily == BPCHAR_BTREE_FAM_OID && (pstatus == Pattern_Prefix_Exact || lc_collate_is_c(idxcollation))); break; case OID_NAME_LIKE_OP: case OID_NAME_ICLIKE_OP: case OID_NAME_REGEXEQ_OP: case OID_NAME_ICREGEXEQ_OP: /* name uses locale-insensitive sorting */ isIndexable = (opfamily == NAME_BTREE_FAM_OID); break; case OID_BYTEA_LIKE_OP: isIndexable = (opfamily == BYTEA_BTREE_FAM_OID); break; case OID_INET_SUB_OP: case OID_INET_SUBEQ_OP: isIndexable = (opfamily == NETWORK_BTREE_FAM_OID); break; } return isIndexable; } /* * expand_indexqual_conditions * Given a list of RestrictInfo nodes, produce a list of directly usable * index qual clauses. * * Standard qual clauses (those in the index's opfamily) are passed through * unchanged. Boolean clauses and "special" index operators are expanded * into clauses that the indexscan machinery will know what to do with. * RowCompare clauses are simplified if necessary to create a clause that is * fully checkable by the index. * * In addition to the expressions themselves, there are auxiliary lists * of the index column numbers that the clauses are meant to be used with; * we generate an updated column number list for the result. (This is not * the identical list because one input clause sometimes produces more than * one output clause.) * * The input clauses are sorted by column number, and so the output is too. * (This is depended on in various places in both planner and executor.) */ void expand_indexqual_conditions(IndexOptInfo *index, List *indexclauses, List *indexclausecols, List **indexquals_p, List **indexqualcols_p) { List *indexquals = NIL; List *indexqualcols = NIL; ListCell *lcc, *lci; forboth(lcc, indexclauses, lci, indexclausecols) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lcc); int indexcol = lfirst_int(lci); Expr *clause = rinfo->clause; Oid curFamily = index->opfamily[indexcol]; Oid curCollation = index->indexcollations[indexcol]; /* First check for boolean cases */ if (IsBooleanOpfamily(curFamily)) { Expr *boolqual; boolqual = expand_boolean_index_clause((Node *) clause, indexcol, index); if (boolqual) { indexquals = lappend(indexquals, make_simple_restrictinfo(boolqual)); indexqualcols = lappend_int(indexqualcols, indexcol); continue; } } /* * Else it must be an opclause (usual case), ScalarArrayOp, * RowCompare, or NullTest */ if (is_opclause(clause)) { indexquals = list_concat(indexquals, expand_indexqual_opclause(rinfo, curFamily, curCollation)); /* expand_indexqual_opclause can produce multiple clauses */ while (list_length(indexqualcols) < list_length(indexquals)) indexqualcols = lappend_int(indexqualcols, indexcol); } else if (IsA(clause, ScalarArrayOpExpr)) { /* no extra work at this time */ indexquals = lappend(indexquals, rinfo); indexqualcols = lappend_int(indexqualcols, indexcol); } else if (IsA(clause, RowCompareExpr)) { indexquals = lappend(indexquals, expand_indexqual_rowcompare(rinfo, index, indexcol)); indexqualcols = lappend_int(indexqualcols, indexcol); } else if (IsA(clause, NullTest)) { Assert(index->amsearchnulls); indexquals = lappend(indexquals, rinfo); indexqualcols = lappend_int(indexqualcols, indexcol); } else elog(ERROR, "unsupported indexqual type: %d", (int) nodeTag(clause)); } *indexquals_p = indexquals; *indexqualcols_p = indexqualcols; } /* * expand_boolean_index_clause * Convert a clause recognized by match_boolean_index_clause into * a boolean equality operator clause. * * Returns NULL if the clause isn't a boolean index qual. */ static Expr * expand_boolean_index_clause(Node *clause, int indexcol, IndexOptInfo *index) { /* Direct match? */ if (match_index_to_operand(clause, indexcol, index)) { /* convert to indexkey = TRUE */ return make_opclause(BooleanEqualOperator, BOOLOID, false, (Expr *) clause, (Expr *) makeBoolConst(true, false), InvalidOid, InvalidOid); } /* NOT clause? */ if (not_clause(clause)) { Node *arg = (Node *) get_notclausearg((Expr *) clause); /* It must have matched the indexkey */ Assert(match_index_to_operand(arg, indexcol, index)); /* convert to indexkey = FALSE */ return make_opclause(BooleanEqualOperator, BOOLOID, false, (Expr *) arg, (Expr *) makeBoolConst(false, false), InvalidOid, InvalidOid); } if (clause && IsA(clause, BooleanTest)) { BooleanTest *btest = (BooleanTest *) clause; Node *arg = (Node *) btest->arg; /* It must have matched the indexkey */ Assert(match_index_to_operand(arg, indexcol, index)); if (btest->booltesttype == IS_TRUE) { /* convert to indexkey = TRUE */ return make_opclause(BooleanEqualOperator, BOOLOID, false, (Expr *) arg, (Expr *) makeBoolConst(true, false), InvalidOid, InvalidOid); } if (btest->booltesttype == IS_FALSE) { /* convert to indexkey = FALSE */ return make_opclause(BooleanEqualOperator, BOOLOID, false, (Expr *) arg, (Expr *) makeBoolConst(false, false), InvalidOid, InvalidOid); } /* Oops */ Assert(false); } return NULL; } /* * expand_indexqual_opclause --- expand a single indexqual condition * that is an operator clause * * The input is a single RestrictInfo, the output a list of RestrictInfos. * * In the base case this is just list_make1(), but we have to be prepared to * expand special cases that were accepted by match_special_index_operator(). */ static List * expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily, Oid idxcollation) { Expr *clause = rinfo->clause; /* we know these will succeed */ Node *leftop = get_leftop(clause); Node *rightop = get_rightop(clause); Oid expr_op = ((OpExpr *) clause)->opno; Oid expr_coll = ((OpExpr *) clause)->inputcollid; Const *patt = (Const *) rightop; Const *prefix = NULL; Pattern_Prefix_Status pstatus; /* * LIKE and regex operators are not members of any btree index opfamily, * but they can be members of opfamilies for more exotic index types such * as GIN. Therefore, we should only do expansion if the operator is * actually not in the opfamily. But checking that requires a syscache * lookup, so it's best to first see if the operator is one we are * interested in. */ switch (expr_op) { case OID_TEXT_LIKE_OP: case OID_BPCHAR_LIKE_OP: case OID_NAME_LIKE_OP: case OID_BYTEA_LIKE_OP: if (!op_in_opfamily(expr_op, opfamily)) { pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like, expr_coll, &prefix, NULL); return prefix_quals(leftop, opfamily, idxcollation, prefix, pstatus); } break; case OID_TEXT_ICLIKE_OP: case OID_BPCHAR_ICLIKE_OP: case OID_NAME_ICLIKE_OP: if (!op_in_opfamily(expr_op, opfamily)) { /* the right-hand const is type text for all of these */ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like_IC, expr_coll, &prefix, NULL); return prefix_quals(leftop, opfamily, idxcollation, prefix, pstatus); } break; case OID_TEXT_REGEXEQ_OP: case OID_BPCHAR_REGEXEQ_OP: case OID_NAME_REGEXEQ_OP: if (!op_in_opfamily(expr_op, opfamily)) { /* the right-hand const is type text for all of these */ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex, expr_coll, &prefix, NULL); return prefix_quals(leftop, opfamily, idxcollation, prefix, pstatus); } break; case OID_TEXT_ICREGEXEQ_OP: case OID_BPCHAR_ICREGEXEQ_OP: case OID_NAME_ICREGEXEQ_OP: if (!op_in_opfamily(expr_op, opfamily)) { /* the right-hand const is type text for all of these */ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex_IC, expr_coll, &prefix, NULL); return prefix_quals(leftop, opfamily, idxcollation, prefix, pstatus); } break; case OID_INET_SUB_OP: case OID_INET_SUBEQ_OP: if (!op_in_opfamily(expr_op, opfamily)) { return network_prefix_quals(leftop, expr_op, opfamily, patt->constvalue); } break; } /* Default case: just make a list of the unmodified indexqual */ return list_make1(rinfo); } /* * expand_indexqual_rowcompare --- expand a single indexqual condition * that is a RowCompareExpr * * This is a thin wrapper around adjust_rowcompare_for_index; we export the * latter so that createplan.c can use it to re-discover which columns of the * index are used by a row comparison indexqual. */ static RestrictInfo * expand_indexqual_rowcompare(RestrictInfo *rinfo, IndexOptInfo *index, int indexcol) { RowCompareExpr *clause = (RowCompareExpr *) rinfo->clause; Expr *newclause; List *indexcolnos; bool var_on_left; newclause = adjust_rowcompare_for_index(clause, index, indexcol, &indexcolnos, &var_on_left); /* * If we didn't have to change the RowCompareExpr, return the original * RestrictInfo. */ if (newclause == (Expr *) clause) return rinfo; /* Else we need a new RestrictInfo */ return make_simple_restrictinfo(newclause); } /* * adjust_rowcompare_for_index --- 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. 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 essentially building a * lossy version of the row comparison when we do this.) * * *indexcolnos receives an integer list of the index column numbers (zero * based) used in the resulting expression. The reason we need to return * that is that if the index is selected for use, createplan.c will need to * call this again to extract that list. (This is a bit grotty, but row * comparison indexquals aren't used enough to justify finding someplace to * keep the information in the Path representation.) Since createplan.c * also needs to know which side of the RowCompareExpr is the index side, * we also return *var_on_left_p rather than re-deducing that there. */ Expr * adjust_rowcompare_for_index(RowCompareExpr *clause, IndexOptInfo *index, int indexcol, List **indexcolnos, bool *var_on_left_p) { bool var_on_left; int op_strategy; Oid op_lefttype; Oid op_righttype; int matching_cols; Oid expr_op; List *opfamilies; List *lefttypes; List *righttypes; List *new_ops; ListCell *largs_cell; ListCell *rargs_cell; ListCell *opnos_cell; ListCell *collids_cell; /* We have to figure out (again) how the first col matches */ var_on_left = match_index_to_operand((Node *) linitial(clause->largs), indexcol, index); Assert(var_on_left || match_index_to_operand((Node *) linitial(clause->rargs), indexcol, index)); *var_on_left_p = var_on_left; expr_op = linitial_oid(clause->opnos); if (!var_on_left) expr_op = get_commutator(expr_op); 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 */ *indexcolnos = list_make1_int(indexcol); /* Build lists of the opfamilies and operator datatypes in case needed */ 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; largs_cell = lnext(list_head(clause->largs)); rargs_cell = lnext(list_head(clause->rargs)); opnos_cell = lnext(list_head(clause->opnos)); collids_cell = lnext(list_head(clause->inputcollids)); while (largs_cell != NULL) { Node *varop; Node *constop; int i; expr_op = lfirst_oid(opnos_cell); if (var_on_left) { varop = (Node *) lfirst(largs_cell); constop = (Node *) lfirst(rargs_cell); } else { varop = (Node *) lfirst(rargs_cell); constop = (Node *) lfirst(largs_cell); /* 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(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 column of the index. */ for (i = 0; i < index->ncolumns; i++) { if (match_index_to_operand(varop, i, index) && get_op_opfamily_strategy(expr_op, index->opfamily[i]) == op_strategy && IndexCollMatchesExprColl(index->indexcollations[i], lfirst_oid(collids_cell))) break; } if (i >= index->ncolumns) break; /* no match found */ /* Add column number to returned list */ *indexcolnos = lappend_int(*indexcolnos, i); /* Add opfamily and datatypes to lists */ get_op_opfamily_properties(expr_op, index->opfamily[i], false, &op_strategy, &op_lefttype, &op_righttype); 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++; largs_cell = lnext(largs_cell); rargs_cell = lnext(rargs_cell); opnos_cell = lnext(opnos_cell); collids_cell = lnext(collids_cell); } /* Return clause as-is if it's all usable as index quals */ if (matching_cols == list_length(clause->opnos)) return (Expr *) clause; /* * We have to generate a subset rowcompare (possibly just one OpExpr). The * painful part of this is changing < to <= or > to >=, so deal with that * first. */ if (op_strategy == BTLessEqualStrategyNumber || op_strategy == BTGreaterEqualStrategyNumber) { /* easy, just use the same operators */ new_ops = list_truncate(list_copy(clause->opnos), 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; lefttypes_cell = list_head(lefttypes); righttypes_cell = list_head(righttypes); foreach(opfamilies_cell, opfamilies) { 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, "could not find member %d(%u,%u) of opfamily %u", op_strategy, lefttype, righttype, opfam); if (!var_on_left) { expr_op = get_commutator(expr_op); if (!OidIsValid(expr_op)) /* should not happen */ elog(ERROR, "could not find commutator of member %d(%u,%u) of opfamily %u", op_strategy, lefttype, righttype, opfam); } new_ops = lappend_oid(new_ops, expr_op); lefttypes_cell = lnext(lefttypes_cell); righttypes_cell = lnext(righttypes_cell); } } /* If we have more than one matching col, create a subset rowcompare */ if (matching_cols > 1) { RowCompareExpr *rc = makeNode(RowCompareExpr); if (var_on_left) rc->rctype = (RowCompareType) op_strategy; else rc->rctype = (op_strategy == BTLessEqualStrategyNumber) ? ROWCOMPARE_GE : ROWCOMPARE_LE; rc->opnos = new_ops; rc->opfamilies = list_truncate(list_copy(clause->opfamilies), matching_cols); rc->inputcollids = list_truncate(list_copy(clause->inputcollids), matching_cols); rc->largs = list_truncate((List *) copyObject(clause->largs), matching_cols); rc->rargs = list_truncate((List *) copyObject(clause->rargs), matching_cols); return (Expr *) rc; } else { return make_opclause(linitial_oid(new_ops), BOOLOID, false, copyObject(linitial(clause->largs)), copyObject(linitial(clause->rargs)), InvalidOid, linitial_oid(clause->inputcollids)); } } /* * Given a fixed prefix that all the "leftop" values must have, * generate suitable indexqual condition(s). opfamily is the index * operator family; we use it to deduce the appropriate comparison * operators and operand datatypes. collation is the input collation to use. */ static List * prefix_quals(Node *leftop, Oid opfamily, Oid collation, Const *prefix_const, Pattern_Prefix_Status pstatus) { List *result; Oid datatype; Oid oproid; Expr *expr; FmgrInfo ltproc; Const *greaterstr; Assert(pstatus != Pattern_Prefix_None); switch (opfamily) { case TEXT_BTREE_FAM_OID: case TEXT_PATTERN_BTREE_FAM_OID: case TEXT_SPGIST_FAM_OID: datatype = TEXTOID; break; case BPCHAR_BTREE_FAM_OID: case BPCHAR_PATTERN_BTREE_FAM_OID: datatype = BPCHAROID; break; case NAME_BTREE_FAM_OID: datatype = NAMEOID; break; case BYTEA_BTREE_FAM_OID: datatype = BYTEAOID; break; default: /* shouldn't get here */ elog(ERROR, "unexpected opfamily: %u", opfamily); return NIL; } /* * If necessary, coerce the prefix constant to the right type. The given * prefix constant is either text or bytea type. */ if (prefix_const->consttype != datatype) { char *prefix; switch (prefix_const->consttype) { case TEXTOID: prefix = TextDatumGetCString(prefix_const->constvalue); break; case BYTEAOID: prefix = DatumGetCString(DirectFunctionCall1(byteaout, prefix_const->constvalue)); break; default: elog(ERROR, "unexpected const type: %u", prefix_const->consttype); return NIL; } prefix_const = string_to_const(prefix, datatype); pfree(prefix); } /* * If we found an exact-match pattern, generate an "=" indexqual. */ if (pstatus == Pattern_Prefix_Exact) { oproid = get_opfamily_member(opfamily, datatype, datatype, BTEqualStrategyNumber); if (oproid == InvalidOid) elog(ERROR, "no = operator for opfamily %u", opfamily); expr = make_opclause(oproid, BOOLOID, false, (Expr *) leftop, (Expr *) prefix_const, InvalidOid, collation); result = list_make1(make_simple_restrictinfo(expr)); return result; } /* * Otherwise, we have a nonempty required prefix of the values. * * We can always say "x >= prefix". */ oproid = get_opfamily_member(opfamily, datatype, datatype, BTGreaterEqualStrategyNumber); if (oproid == InvalidOid) elog(ERROR, "no >= operator for opfamily %u", opfamily); expr = make_opclause(oproid, BOOLOID, false, (Expr *) leftop, (Expr *) prefix_const, InvalidOid, collation); result = list_make1(make_simple_restrictinfo(expr)); /*------- * If we can create a string larger than the prefix, we can say * "x < greaterstr". NB: we rely on make_greater_string() to generate * a guaranteed-greater string, not just a probably-greater string. * In general this is only guaranteed in C locale, so we'd better be * using a C-locale index collation. *------- */ oproid = get_opfamily_member(opfamily, datatype, datatype, BTLessStrategyNumber); if (oproid == InvalidOid) elog(ERROR, "no < operator for opfamily %u", opfamily); fmgr_info(get_opcode(oproid), <proc); greaterstr = make_greater_string(prefix_const, <proc, collation); if (greaterstr) { expr = make_opclause(oproid, BOOLOID, false, (Expr *) leftop, (Expr *) greaterstr, InvalidOid, collation); result = lappend(result, make_simple_restrictinfo(expr)); } return result; } /* * Given a leftop and a rightop, and a inet-family sup/sub operator, * generate suitable indexqual condition(s). expr_op is the original * operator, and opfamily is the index opfamily. */ static List * network_prefix_quals(Node *leftop, Oid expr_op, Oid opfamily, Datum rightop) { bool is_eq; Oid datatype; Oid opr1oid; Oid opr2oid; Datum opr1right; Datum opr2right; List *result; Expr *expr; switch (expr_op) { case OID_INET_SUB_OP: datatype = INETOID; is_eq = false; break; case OID_INET_SUBEQ_OP: datatype = INETOID; is_eq = true; break; default: elog(ERROR, "unexpected operator: %u", expr_op); return NIL; } /* * create clause "key >= network_scan_first( rightop )", or ">" if the * operator disallows equality. */ if (is_eq) { opr1oid = get_opfamily_member(opfamily, datatype, datatype, BTGreaterEqualStrategyNumber); if (opr1oid == InvalidOid) elog(ERROR, "no >= operator for opfamily %u", opfamily); } else { opr1oid = get_opfamily_member(opfamily, datatype, datatype, BTGreaterStrategyNumber); if (opr1oid == InvalidOid) elog(ERROR, "no > operator for opfamily %u", opfamily); } opr1right = network_scan_first(rightop); expr = make_opclause(opr1oid, BOOLOID, false, (Expr *) leftop, (Expr *) makeConst(datatype, -1, InvalidOid, /* not collatable */ -1, opr1right, false, false), InvalidOid, InvalidOid); result = list_make1(make_simple_restrictinfo(expr)); /* create clause "key <= network_scan_last( rightop )" */ opr2oid = get_opfamily_member(opfamily, datatype, datatype, BTLessEqualStrategyNumber); if (opr2oid == InvalidOid) elog(ERROR, "no <= operator for opfamily %u", opfamily); opr2right = network_scan_last(rightop); expr = make_opclause(opr2oid, BOOLOID, false, (Expr *) leftop, (Expr *) makeConst(datatype, -1, InvalidOid, /* not collatable */ -1, opr2right, false, false), InvalidOid, InvalidOid); result = lappend(result, make_simple_restrictinfo(expr)); return result; } /* * Handy subroutines for match_special_index_operator() and friends. */ /* * Generate a Datum of the appropriate type from a C string. * Note that all of the supported types are pass-by-ref, so the * returned value should be pfree'd if no longer needed. */ static Datum string_to_datum(const char *str, Oid datatype) { /* * We cheat a little by assuming that CStringGetTextDatum() will do for * bpchar and varchar constants too... */ if (datatype == NAMEOID) return DirectFunctionCall1(namein, CStringGetDatum(str)); else if (datatype == BYTEAOID) return DirectFunctionCall1(byteain, CStringGetDatum(str)); else return CStringGetTextDatum(str); } /* * Generate a Const node of the appropriate type from a C string. */ static Const * string_to_const(const char *str, Oid datatype) { Datum conval = string_to_datum(str, datatype); Oid collation; int constlen; /* * We only need to support a few datatypes here, so hard-wire properties * instead of incurring the expense of catalog lookups. */ switch (datatype) { case TEXTOID: case VARCHAROID: case BPCHAROID: collation = DEFAULT_COLLATION_OID; constlen = -1; break; case NAMEOID: collation = InvalidOid; constlen = NAMEDATALEN; break; case BYTEAOID: collation = InvalidOid; constlen = -1; break; default: elog(ERROR, "unexpected datatype in string_to_const: %u", datatype); return NULL; } return makeConst(datatype, -1, collation, constlen, conval, false, false); }