diff options
Diffstat (limited to 'src/backend/optimizer')
| -rw-r--r-- | src/backend/optimizer/path/clausesel.c | 109 | ||||
| -rw-r--r-- | src/backend/optimizer/util/plancat.c | 12 |
2 files changed, 79 insertions, 42 deletions
diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c index e8142bddf02..9dae586a518 100644 --- a/src/backend/optimizer/path/clausesel.c +++ b/src/backend/optimizer/path/clausesel.c @@ -60,17 +60,67 @@ static RelOptInfo *find_single_rel_for_clauses(PlannerInfo *root, * * See clause_selectivity() for the meaning of the additional parameters. * + * The basic approach is to apply extended statistics first, on as many + * clauses as possible, in order to capture cross-column dependencies etc. + * The remaining clauses are then estimated using regular statistics tracked + * for individual columns. This is done by simply passing the clauses to + * clauselist_selectivity_simple. + */ +Selectivity +clauselist_selectivity(PlannerInfo *root, + List *clauses, + int varRelid, + JoinType jointype, + SpecialJoinInfo *sjinfo) +{ + Selectivity s1 = 1.0; + RelOptInfo *rel; + Bitmapset *estimatedclauses = NULL; + + /* + * Determine if these clauses reference a single relation. If so, and if + * it has extended statistics, try to apply those. + */ + rel = find_single_rel_for_clauses(root, clauses); + if (rel && rel->rtekind == RTE_RELATION && rel->statlist != NIL) + { + /* + * Estimate as many clauses as possible using extended statistics. + * + * 'estimatedclauses' tracks the 0-based list position index of + * clauses that we've estimated using extended statistics, and that + * should be ignored. + */ + s1 *= statext_clauselist_selectivity(root, clauses, varRelid, + jointype, sjinfo, rel, + &estimatedclauses); + } + + /* + * Apply normal selectivity estimates for the remaining clauses, passing + * 'estimatedclauses' so that it skips already estimated ones. + */ + return s1 * clauselist_selectivity_simple(root, clauses, varRelid, + jointype, sjinfo, + estimatedclauses); +} + +/* + * clauselist_selectivity_simple - + * Compute the selectivity of an implicitly-ANDed list of boolean + * expression clauses. The list can be empty, in which case 1.0 + * must be returned. List elements may be either RestrictInfos + * or bare expression clauses --- the former is preferred since + * it allows caching of results. The estimatedclauses bitmap tracks + * clauses that have already been estimated by other means. + * + * See clause_selectivity() for the meaning of the additional parameters. + * * Our basic approach is to take the product of the selectivities of the * subclauses. However, that's only right if the subclauses have independent * probabilities, and in reality they are often NOT independent. So, * we want to be smarter where we can. * - * If the clauses taken together refer to just one relation, we'll try to - * apply selectivity estimates using any extended statistics for that rel. - * Currently we only have (soft) functional dependencies, so apply these in as - * many cases as possible, and fall back on normal estimates for remaining - * clauses. - * * We also recognize "range queries", such as "x > 34 AND x < 42". Clauses * are recognized as possible range query components if they are restriction * opclauses whose operators have scalarltsel or a related function as their @@ -98,54 +148,29 @@ static RelOptInfo *find_single_rel_for_clauses(PlannerInfo *root, * selectivity functions; perhaps some day we can generalize the approach. */ Selectivity -clauselist_selectivity(PlannerInfo *root, - List *clauses, - int varRelid, - JoinType jointype, - SpecialJoinInfo *sjinfo) +clauselist_selectivity_simple(PlannerInfo *root, + List *clauses, + int varRelid, + JoinType jointype, + SpecialJoinInfo *sjinfo, + Bitmapset *estimatedclauses) { Selectivity s1 = 1.0; - RelOptInfo *rel; - Bitmapset *estimatedclauses = NULL; RangeQueryClause *rqlist = NULL; ListCell *l; int listidx; /* - * If there's exactly one clause, just go directly to - * clause_selectivity(). None of what we might do below is relevant. + * If there's exactly one clause (and it was not estimated yet), just + * go directly to clause_selectivity(). None of what we might do below + * is relevant. */ - if (list_length(clauses) == 1) + if ((list_length(clauses) == 1) && + bms_num_members(estimatedclauses) == 0) return clause_selectivity(root, (Node *) linitial(clauses), varRelid, jointype, sjinfo); /* - * Determine if these clauses reference a single relation. If so, and if - * it has extended statistics, try to apply those. - */ - rel = find_single_rel_for_clauses(root, clauses); - if (rel && rel->rtekind == RTE_RELATION && rel->statlist != NIL) - { - /* - * Perform selectivity estimations on any clauses found applicable by - * dependencies_clauselist_selectivity. 'estimatedclauses' will be - * filled with the 0-based list positions of clauses used that way, so - * that we can ignore them below. - */ - s1 *= dependencies_clauselist_selectivity(root, clauses, varRelid, - jointype, sjinfo, rel, - &estimatedclauses); - - /* - * This would be the place to apply any other types of extended - * statistics selectivity estimations for remaining clauses. - */ - } - - /* - * Apply normal selectivity estimates for remaining clauses. We'll be - * careful to skip any clauses which were already estimated above. - * * Anything that doesn't look like a potential rangequery clause gets * multiplied into s1 and forgotten. Anything that does gets inserted into * an rqlist entry. diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c index 702c4f89b82..a0a7c5442de 100644 --- a/src/backend/optimizer/util/plancat.c +++ b/src/backend/optimizer/util/plancat.c @@ -1363,6 +1363,18 @@ get_relation_statistics(RelOptInfo *rel, Relation relation) stainfos = lcons(info, stainfos); } + if (statext_is_kind_built(htup, STATS_EXT_MCV)) + { + StatisticExtInfo *info = makeNode(StatisticExtInfo); + + info->statOid = statOid; + info->rel = rel; + info->kind = STATS_EXT_MCV; + info->keys = bms_copy(keys); + + stainfos = lcons(info, stainfos); + } + ReleaseSysCache(htup); bms_free(keys); } |