diff options
Diffstat (limited to 'src/backend/optimizer/path')
| -rw-r--r-- | src/backend/optimizer/path/equivclass.c | 14 | ||||
| -rw-r--r-- | src/backend/optimizer/path/pathkeys.c | 247 |
2 files changed, 169 insertions, 92 deletions
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c index fc862438ffb..18c6ff93686 100644 --- a/src/backend/optimizer/path/equivclass.c +++ b/src/backend/optimizer/path/equivclass.c @@ -10,7 +10,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.3 2007/07/07 20:46:45 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.4 2007/11/08 21:49:47 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -294,6 +294,7 @@ process_equivalence(PlannerInfo *root, RestrictInfo *restrictinfo, ec->ec_has_volatile = false; ec->ec_below_outer_join = below_outer_join; ec->ec_broken = false; + ec->ec_sortref = 0; ec->ec_merged = NULL; em1 = add_eq_member(ec, item1, item1_relids, false, item1_type); em2 = add_eq_member(ec, item2, item2_relids, false, item2_type); @@ -354,6 +355,9 @@ add_eq_member(EquivalenceClass *ec, Expr *expr, Relids relids, * class it is a member of; if none, build a new single-member * EquivalenceClass for it. * + * sortref is the SortGroupRef of the originating SortClause, if any, + * or zero if not. + * * This can be used safely both before and after EquivalenceClass merging; * since it never causes merging it does not invalidate any existing ECs * or PathKeys. @@ -367,7 +371,8 @@ EquivalenceClass * get_eclass_for_sort_expr(PlannerInfo *root, Expr *expr, Oid expr_datatype, - List *opfamilies) + List *opfamilies, + Index sortref) { EquivalenceClass *newec; EquivalenceMember *newem; @@ -382,7 +387,9 @@ get_eclass_for_sort_expr(PlannerInfo *root, EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1); ListCell *lc2; - /* we allow matching to a volatile EC here */ + /* Never match to a volatile EC */ + if (cur_ec->ec_has_volatile) + continue; if (!equal(opfamilies, cur_ec->ec_opfamilies)) continue; @@ -423,6 +430,7 @@ get_eclass_for_sort_expr(PlannerInfo *root, newec->ec_has_volatile = contain_volatile_functions((Node *) expr); newec->ec_below_outer_join = false; newec->ec_broken = false; + newec->ec_sortref = sortref; newec->ec_merged = NULL; newem = add_eq_member(newec, expr, pull_varnos((Node *) expr), false, expr_datatype); diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c index f96d7bb5554..846fe78ee6c 100644 --- a/src/backend/optimizer/path/pathkeys.c +++ b/src/backend/optimizer/path/pathkeys.c @@ -11,7 +11,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.88 2007/11/08 19:25:37 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.89 2007/11/08 21:49:47 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -46,6 +46,7 @@ static bool pathkey_is_redundant(PathKey *new_pathkey, List *pathkeys); static PathKey *make_pathkey_from_sortinfo(PlannerInfo *root, Expr *expr, Oid ordering_op, bool nulls_first, + Index sortref, bool canonicalize); static Var *find_indexkey_var(PlannerInfo *root, RelOptInfo *rel, AttrNumber varattno); @@ -233,6 +234,9 @@ canonicalize_pathkeys(PlannerInfo *root, List *pathkeys) * a PathKey. If canonicalize = true, the result is a "canonical" * PathKey, otherwise not. (But note it might be redundant anyway.) * + * If the PathKey is being generated from a SortClause, sortref should be + * the SortClause's SortGroupRef; otherwise zero. + * * canonicalize should always be TRUE after EquivalenceClass merging has * been performed, but FALSE if we haven't done EquivalenceClass merging yet. */ @@ -240,6 +244,7 @@ static PathKey * make_pathkey_from_sortinfo(PlannerInfo *root, Expr *expr, Oid ordering_op, bool nulls_first, + Index sortref, bool canonicalize) { Oid opfamily, @@ -303,7 +308,8 @@ make_pathkey_from_sortinfo(PlannerInfo *root, } /* Now find or create a matching EquivalenceClass */ - eclass = get_eclass_for_sort_expr(root, expr, opcintype, opfamilies); + eclass = get_eclass_for_sort_expr(root, expr, opcintype, opfamilies, + sortref); /* And finally we can find or create a PathKey node */ if (canonicalize) @@ -525,6 +531,7 @@ build_index_pathkeys(PlannerInfo *root, indexkey, sortop, nulls_first, + 0, true); /* Add to list unless redundant */ @@ -597,102 +604,161 @@ convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel, PathKey *sub_pathkey = (PathKey *) lfirst(i); EquivalenceClass *sub_eclass = sub_pathkey->pk_eclass; PathKey *best_pathkey = NULL; - int best_score = -1; - ListCell *j; - /* - * The sub_pathkey's EquivalenceClass could contain multiple elements - * (representing knowledge that multiple items are effectively equal). - * Each element might match none, one, or more of the output columns - * that are visible to the outer query. This means we may have - * multiple possible representations of the sub_pathkey in the context - * of the outer query. Ideally we would generate them all and put - * them all into an EC of the outer query, thereby propagating - * equality knowledge up to the outer query. Right now we cannot do - * so, because the outer query's EquivalenceClasses are already frozen - * when this is called. Instead we prefer the one that has the highest - * "score" (number of EC peers, plus one if it matches the outer - * query_pathkeys). This is the most likely to be useful in the outer - * query. - */ - foreach(j, sub_eclass->ec_members) + if (sub_eclass->ec_has_volatile) { - EquivalenceMember *sub_member = (EquivalenceMember *) lfirst(j); - Expr *sub_expr = sub_member->em_expr; - Expr *rtarg; - ListCell *k; - /* - * We handle two cases: the sub_pathkey key can be either an exact - * match for a targetlist entry, or a RelabelType of a targetlist - * entry. (The latter case is worth extra code because it arises - * frequently in connection with varchar fields.) + * If the sub_pathkey's EquivalenceClass is volatile, then it must + * have come from an ORDER BY clause, and we have to match it to + * that same targetlist entry. */ - if (IsA(sub_expr, RelabelType)) - rtarg = ((RelabelType *) sub_expr)->arg; - else - rtarg = NULL; - - foreach(k, sub_tlist) + TargetEntry *tle; + + if (sub_eclass->ec_sortref == 0) /* can't happen */ + elog(ERROR, "volatile EquivalenceClass has no sortref"); + tle = get_sortgroupref_tle(sub_eclass->ec_sortref, sub_tlist); + Assert(tle); + /* resjunk items aren't visible to outer query */ + if (!tle->resjunk) { - TargetEntry *tle = (TargetEntry *) lfirst(k); + /* We can represent this sub_pathkey */ + EquivalenceMember *sub_member; Expr *outer_expr; EquivalenceClass *outer_ec; - PathKey *outer_pk; - int score; - /* resjunk items aren't visible to outer query */ - if (tle->resjunk) - continue; + Assert(list_length(sub_eclass->ec_members) == 1); + sub_member = (EquivalenceMember *) linitial(sub_eclass->ec_members); + outer_expr = (Expr *) + makeVar(rel->relid, + tle->resno, + exprType((Node *) tle->expr), + exprTypmod((Node *) tle->expr), + 0); + outer_ec = + get_eclass_for_sort_expr(root, + outer_expr, + sub_member->em_datatype, + sub_eclass->ec_opfamilies, + 0); + best_pathkey = + make_canonical_pathkey(root, + outer_ec, + sub_pathkey->pk_opfamily, + sub_pathkey->pk_strategy, + sub_pathkey->pk_nulls_first); + } + } + else + { + /* + * Otherwise, the sub_pathkey's EquivalenceClass could contain + * multiple elements (representing knowledge that multiple items + * are effectively equal). Each element might match none, one, or + * more of the output columns that are visible to the outer + * query. This means we may have multiple possible representations + * of the sub_pathkey in the context of the outer query. Ideally + * we would generate them all and put them all into an EC of the + * outer query, thereby propagating equality knowledge up to the + * outer query. Right now we cannot do so, because the outer + * query's EquivalenceClasses are already frozen when this is + * called. Instead we prefer the one that has the highest "score" + * (number of EC peers, plus one if it matches the outer + * query_pathkeys). This is the most likely to be useful in the + * outer query. + */ + int best_score = -1; + ListCell *j; - if (equal(tle->expr, sub_expr)) - { - /* Exact match */ - outer_expr = (Expr *) - makeVar(rel->relid, - tle->resno, - exprType((Node *) tle->expr), - exprTypmod((Node *) tle->expr), - 0); - } - else if (rtarg && equal(tle->expr, rtarg)) + foreach(j, sub_eclass->ec_members) + { + EquivalenceMember *sub_member = (EquivalenceMember *) lfirst(j); + Expr *sub_expr = sub_member->em_expr; + Expr *sub_stripped; + ListCell *k; + + /* + * We handle two cases: the sub_pathkey key can be either an + * exact match for a targetlist entry, or it could match after + * stripping RelabelType nodes. (We need that case since + * make_pathkey_from_sortinfo could add or remove RelabelType.) + */ + sub_stripped = sub_expr; + while (sub_stripped && IsA(sub_stripped, RelabelType)) + sub_stripped = ((RelabelType *) sub_stripped)->arg; + + foreach(k, sub_tlist) { - /* Match after discarding RelabelType */ - outer_expr = (Expr *) - makeVar(rel->relid, - tle->resno, - exprType((Node *) tle->expr), - exprTypmod((Node *) tle->expr), - 0); - outer_expr = (Expr *) - makeRelabelType((Expr *) outer_expr, - ((RelabelType *) sub_expr)->resulttype, - ((RelabelType *) sub_expr)->resulttypmod, - ((RelabelType *) sub_expr)->relabelformat); - } - else - continue; + TargetEntry *tle = (TargetEntry *) lfirst(k); + Expr *outer_expr; + EquivalenceClass *outer_ec; + PathKey *outer_pk; + int score; - /* Found a representation for this sub_pathkey */ - outer_ec = get_eclass_for_sort_expr(root, - outer_expr, - sub_member->em_datatype, - sub_eclass->ec_opfamilies); - outer_pk = make_canonical_pathkey(root, - outer_ec, - sub_pathkey->pk_opfamily, - sub_pathkey->pk_strategy, - sub_pathkey->pk_nulls_first); - /* score = # of equivalence peers */ - score = list_length(outer_ec->ec_members) - 1; - /* +1 if it matches the proper query_pathkeys item */ - if (retvallen < outer_query_keys && - list_nth(root->query_pathkeys, retvallen) == outer_pk) - score++; - if (score > best_score) - { - best_pathkey = outer_pk; - best_score = score; + /* resjunk items aren't visible to outer query */ + if (tle->resjunk) + continue; + + if (equal(tle->expr, sub_expr)) + { + /* Exact match */ + outer_expr = (Expr *) + makeVar(rel->relid, + tle->resno, + exprType((Node *) tle->expr), + exprTypmod((Node *) tle->expr), + 0); + } + else + { + Expr *tle_stripped; + + tle_stripped = tle->expr; + while (tle_stripped && IsA(tle_stripped, RelabelType)) + tle_stripped = ((RelabelType *) tle_stripped)->arg; + + if (equal(tle_stripped, sub_stripped)) + { + /* Match after discarding RelabelType */ + outer_expr = (Expr *) + makeVar(rel->relid, + tle->resno, + exprType((Node *) tle->expr), + exprTypmod((Node *) tle->expr), + 0); + if (exprType((Node *) outer_expr) != + exprType((Node *) sub_expr)) + outer_expr = (Expr *) + makeRelabelType(outer_expr, + exprType((Node *) sub_expr), + -1, + COERCE_DONTCARE); + } + else + continue; + } + + /* Found a representation for this sub_pathkey */ + outer_ec = get_eclass_for_sort_expr(root, + outer_expr, + sub_member->em_datatype, + sub_eclass->ec_opfamilies, + 0); + outer_pk = make_canonical_pathkey(root, + outer_ec, + sub_pathkey->pk_opfamily, + sub_pathkey->pk_strategy, + sub_pathkey->pk_nulls_first); + /* score = # of equivalence peers */ + score = list_length(outer_ec->ec_members) - 1; + /* +1 if it matches the proper query_pathkeys item */ + if (retvallen < outer_query_keys && + list_nth(root->query_pathkeys, retvallen) == outer_pk) + score++; + if (score > best_score) + { + best_pathkey = outer_pk; + best_score = score; + } } } } @@ -795,6 +861,7 @@ make_pathkeys_for_sortclauses(PlannerInfo *root, sortkey, sortcl->sortop, sortcl->nulls_first, + sortcl->tleSortGroupRef, canonicalize); /* Canonical form eliminates redundant ordering keys */ @@ -843,12 +910,14 @@ cache_mergeclause_eclasses(PlannerInfo *root, RestrictInfo *restrictinfo) get_eclass_for_sort_expr(root, (Expr *) get_leftop(clause), lefttype, - restrictinfo->mergeopfamilies); + restrictinfo->mergeopfamilies, + 0); restrictinfo->right_ec = get_eclass_for_sort_expr(root, (Expr *) get_rightop(clause), righttype, - restrictinfo->mergeopfamilies); + restrictinfo->mergeopfamilies, + 0); } else Assert(restrictinfo->right_ec != NULL); |