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