diff options
Diffstat (limited to 'src/backend/optimizer/plan/analyzejoins.c')
| -rw-r--r-- | src/backend/optimizer/plan/analyzejoins.c | 1284 |
1 files changed, 66 insertions, 1218 deletions
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c index 506fccd20c9..aa725925675 100644 --- a/src/backend/optimizer/plan/analyzejoins.c +++ b/src/backend/optimizer/plan/analyzejoins.c @@ -22,7 +22,6 @@ */ #include "postgres.h" -#include "catalog/pg_class.h" #include "nodes/nodeFuncs.h" #include "optimizer/joininfo.h" #include "optimizer/optimizer.h" @@ -32,22 +31,10 @@ #include "optimizer/restrictinfo.h" #include "utils/lsyscache.h" -/* - * The struct containing self-join candidate. Used to find duplicate reloids. - */ -typedef struct -{ - int relid; - Oid reloid; -} SelfJoinCandidate; - -bool enable_self_join_removal; - /* local functions */ static bool join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo); - -static void remove_leftjoinrel_from_query(PlannerInfo *root, int relid, - SpecialJoinInfo *sjinfo); +static void remove_rel_from_query(PlannerInfo *root, int relid, + SpecialJoinInfo *sjinfo); static void remove_rel_from_restrictinfo(RestrictInfo *rinfo, int relid, int ojrelid); static void remove_rel_from_eclass(EquivalenceClass *ec, @@ -55,18 +42,14 @@ static void remove_rel_from_eclass(EquivalenceClass *ec, static List *remove_rel_from_joinlist(List *joinlist, int relid, int *nremoved); static bool rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel); static bool rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel, - List *clause_list, List **extra_clauses); + List *clause_list); static Oid distinct_col_search(int colno, List *colnos, List *opids); static bool is_innerrel_unique_for(PlannerInfo *root, Relids joinrelids, Relids outerrelids, RelOptInfo *innerrel, JoinType jointype, - List *restrictlist, - List **extra_clauses); -static void replace_varno(Node *node, int from, int to); -static Bitmapset *replace_relid(Relids relids, int oldId, int newId); -static int self_join_candidates_cmp(const void *a, const void *b); + List *restrictlist); /* @@ -104,7 +87,7 @@ restart: */ innerrelid = bms_singleton_member(sjinfo->min_righthand); - remove_leftjoinrel_from_query(root, innerrelid, sjinfo); + remove_rel_from_query(root, innerrelid, sjinfo); /* We verify that exactly one reference gets removed from joinlist */ nremoved = 0; @@ -308,8 +291,8 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo) continue; /* not mergejoinable */ /* - * Check if clause has the form "outer op inner" or "inner op outer", - * and if so mark which side is inner. + * Check if the clause has the form "outer op inner" or "inner op + * outer", and if so mark which side is inner. */ if (!clause_sides_match_join(restrictinfo, sjinfo->min_lefthand, innerrel->relids)) @@ -323,7 +306,7 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo) * Now that we have the relevant equality join clauses, try to prove the * innerrel distinct. */ - if (rel_is_distinct_for(root, innerrel, clause_list, NULL)) + if (rel_is_distinct_for(root, innerrel, clause_list)) return true; /* @@ -335,27 +318,31 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo) /* - * Remove the target rel->relid and references to the target join from the + * Remove the target relid and references to the target join from the * planner's data structures, having determined that there is no need - * to include them in the query. Optionally replace them with subst if subst - * is non-negative. + * to include them in the query. * - * This function updates only parts needed for both left-join removal and - * self-join removal. + * We are not terribly thorough here. We only bother to update parts of + * the planner's data structures that will actually be consulted later. */ static void -remove_rel_from_query(PlannerInfo *root, RelOptInfo *rel, - int subst, SpecialJoinInfo *sjinfo, - Relids joinrelids) +remove_rel_from_query(PlannerInfo *root, int relid, SpecialJoinInfo *sjinfo) { - int relid = rel->relid; - int ojrelid = (sjinfo != NULL) ? sjinfo->ojrelid : -1; + RelOptInfo *rel = find_base_rel(root, relid); + int ojrelid = sjinfo->ojrelid; + Relids joinrelids; + Relids join_plus_commute; + List *joininfos; Index rti; ListCell *l; + /* Compute the relid set for the join we are considering */ + joinrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand); + Assert(ojrelid != 0); + joinrelids = bms_add_member(joinrelids, ojrelid); + /* - * Remove references to the rel from other baserels' attr_needed arrays - * and lateral_vars lists. + * Remove references to the rel from other baserels' attr_needed arrays. */ for (rti = 1; rti < root->simple_rel_array_size; rti++) { @@ -377,22 +364,19 @@ remove_rel_from_query(PlannerInfo *root, RelOptInfo *rel, attroff--) { otherrel->attr_needed[attroff] = - replace_relid(otherrel->attr_needed[attroff], relid, subst); + bms_del_member(otherrel->attr_needed[attroff], relid); otherrel->attr_needed[attroff] = - replace_relid(otherrel->attr_needed[attroff], ojrelid, subst); + bms_del_member(otherrel->attr_needed[attroff], ojrelid); } - - /* Update lateral_vars list. */ - replace_varno((Node *) otherrel->lateral_vars, relid, subst); } /* * Update all_baserels and related relid sets. */ - root->all_baserels = replace_relid(root->all_baserels, relid, subst); - root->outer_join_rels = replace_relid(root->outer_join_rels, ojrelid, subst); - root->all_query_rels = replace_relid(root->all_query_rels, relid, subst); - root->all_query_rels = replace_relid(root->all_query_rels, ojrelid, subst); + root->all_baserels = bms_del_member(root->all_baserels, relid); + root->outer_join_rels = bms_del_member(root->outer_join_rels, ojrelid); + root->all_query_rels = bms_del_member(root->all_query_rels, relid); + root->all_query_rels = bms_del_member(root->all_query_rels, ojrelid); /* * Likewise remove references from SpecialJoinInfo data structures. @@ -406,21 +390,19 @@ remove_rel_from_query(PlannerInfo *root, RelOptInfo *rel, { SpecialJoinInfo *sjinf = (SpecialJoinInfo *) lfirst(l); - sjinf->min_lefthand = replace_relid(sjinf->min_lefthand, relid, subst); - sjinf->min_righthand = replace_relid(sjinf->min_righthand, relid, subst); - sjinf->syn_lefthand = replace_relid(sjinf->syn_lefthand, relid, subst); - sjinf->syn_righthand = replace_relid(sjinf->syn_righthand, relid, subst); - sjinf->min_lefthand = replace_relid(sjinf->min_lefthand, ojrelid, subst); - sjinf->min_righthand = replace_relid(sjinf->min_righthand, ojrelid, subst); - sjinf->syn_lefthand = replace_relid(sjinf->syn_lefthand, ojrelid, subst); - sjinf->syn_righthand = replace_relid(sjinf->syn_righthand, ojrelid, subst); + sjinf->min_lefthand = bms_del_member(sjinf->min_lefthand, relid); + sjinf->min_righthand = bms_del_member(sjinf->min_righthand, relid); + sjinf->syn_lefthand = bms_del_member(sjinf->syn_lefthand, relid); + sjinf->syn_righthand = bms_del_member(sjinf->syn_righthand, relid); + sjinf->min_lefthand = bms_del_member(sjinf->min_lefthand, ojrelid); + sjinf->min_righthand = bms_del_member(sjinf->min_righthand, ojrelid); + sjinf->syn_lefthand = bms_del_member(sjinf->syn_lefthand, ojrelid); + sjinf->syn_righthand = bms_del_member(sjinf->syn_righthand, ojrelid); /* relid cannot appear in these fields, but ojrelid can: */ - sjinf->commute_above_l = replace_relid(sjinf->commute_above_l, ojrelid, subst); - sjinf->commute_above_r = replace_relid(sjinf->commute_above_r, ojrelid, subst); - sjinf->commute_below_l = replace_relid(sjinf->commute_below_l, ojrelid, subst); - sjinf->commute_below_r = replace_relid(sjinf->commute_below_r, ojrelid, subst); - - replace_varno((Node *) sjinf->semi_rhs_exprs, relid, subst); + sjinf->commute_above_l = bms_del_member(sjinf->commute_above_l, ojrelid); + sjinf->commute_above_r = bms_del_member(sjinf->commute_above_r, ojrelid); + sjinf->commute_below_l = bms_del_member(sjinf->commute_below_l, ojrelid); + sjinf->commute_below_r = bms_del_member(sjinf->commute_below_r, ojrelid); } /* @@ -441,10 +423,10 @@ remove_rel_from_query(PlannerInfo *root, RelOptInfo *rel, { PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l); - Assert(sjinfo == NULL || !bms_is_member(relid, phinfo->ph_lateral)); + Assert(!bms_is_member(relid, phinfo->ph_lateral)); if (bms_is_subset(phinfo->ph_needed, joinrelids) && bms_is_member(relid, phinfo->ph_eval_at) && - (sjinfo == NULL || !bms_is_member(ojrelid, phinfo->ph_eval_at))) + !bms_is_member(ojrelid, phinfo->ph_eval_at)) { root->placeholder_list = foreach_delete_current(root->placeholder_list, l); @@ -454,48 +436,18 @@ remove_rel_from_query(PlannerInfo *root, RelOptInfo *rel, { PlaceHolderVar *phv = phinfo->ph_var; - phinfo->ph_eval_at = replace_relid(phinfo->ph_eval_at, relid, subst); - phinfo->ph_eval_at = replace_relid(phinfo->ph_eval_at, ojrelid, subst); + phinfo->ph_eval_at = bms_del_member(phinfo->ph_eval_at, relid); + phinfo->ph_eval_at = bms_del_member(phinfo->ph_eval_at, ojrelid); Assert(!bms_is_empty(phinfo->ph_eval_at)); /* checked previously */ - phinfo->ph_needed = replace_relid(phinfo->ph_needed, relid, subst); - phinfo->ph_needed = replace_relid(phinfo->ph_needed, ojrelid, subst); + phinfo->ph_needed = bms_del_member(phinfo->ph_needed, relid); + phinfo->ph_needed = bms_del_member(phinfo->ph_needed, ojrelid); /* ph_needed might or might not become empty */ - phinfo->ph_lateral = replace_relid(phinfo->ph_lateral, relid, subst); - /* ph_lateral might or might not be empty */ - phv->phrels = replace_relid(phv->phrels, relid, subst); - phv->phrels = replace_relid(phv->phrels, ojrelid, subst); + phv->phrels = bms_del_member(phv->phrels, relid); + phv->phrels = bms_del_member(phv->phrels, ojrelid); Assert(!bms_is_empty(phv->phrels)); - replace_varno((Node *) phv->phexpr, relid, subst); Assert(phv->phnullingrels == NULL); /* no need to adjust */ } } -} - -/* - * Remove the target relid and references to the target join from the - * planner's data structures, having determined that there is no need - * to include them in the query. - * - * We are not terribly thorough here. We only bother to update parts of - * the planner's data structures that will actually be consulted later. - */ -static void -remove_leftjoinrel_from_query(PlannerInfo *root, int relid, - SpecialJoinInfo *sjinfo) -{ - List *joininfos; - int ojrelid = sjinfo->ojrelid; - RelOptInfo *rel = find_base_rel(root, relid); - Relids join_plus_commute; - Relids joinrelids; - ListCell *l; - - /* Compute the relid set for the join we are considering */ - joinrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand); - Assert(ojrelid != 0); - joinrelids = bms_add_member(joinrelids, ojrelid); - - remove_rel_from_query(root, rel, -1, sjinfo, joinrelids); /* * Remove any joinquals referencing the rel from the joininfo lists. @@ -890,14 +842,9 @@ rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel) * Note that the passed-in clause_list may be destructively modified! This * is OK for current uses, because the clause_list is built by the caller for * the sole purpose of passing to this function. - * - * outer_exprs contains the right sides of baserestrictinfo clauses looking - * like x = const if distinctness is derived from such clauses, not joininfo - * clause. Pass NULL to the outer_exprs, if its value is not needed. */ static bool -rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel, List *clause_list, - List **extra_clauses) +rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel, List *clause_list) { /* * We could skip a couple of tests here if we assume all callers checked @@ -910,11 +857,10 @@ rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel, List *clause_list, { /* * Examine the indexes to see if we have a matching unique index. - * relation_has_unique_index_ext automatically adds any usable + * relation_has_unique_index_for automatically adds any usable * restriction clauses for the rel, so we needn't do that here. */ - if (relation_has_unique_index_ext(root, rel, clause_list, NIL, NIL, - extra_clauses)) + if (relation_has_unique_index_for(root, rel, clause_list, NIL, NIL)) return true; } else if (rel->rtekind == RTE_SUBQUERY) @@ -1229,32 +1175,8 @@ innerrel_is_unique(PlannerInfo *root, List *restrictlist, bool force_cache) { - return innerrel_is_unique_ext(root, joinrelids, outerrelids, innerrel, - jointype, restrictlist, force_cache, NULL); -} - -/* - * innerrel_is_unique_ext - * Do the same as innerrel_is_unique(), but also set to '*extra_clauses' - * additional clauses from a baserestrictinfo list that were used to prove - * uniqueness. A non NULL 'extra_clauses' indicates that we're checking - * for self-join and correspondingly dealing with filtered clauses. - */ -bool -innerrel_is_unique_ext(PlannerInfo *root, - Relids joinrelids, - Relids outerrelids, - RelOptInfo *innerrel, - JoinType jointype, - List *restrictlist, - bool force_cache, - List **extra_clauses) -{ MemoryContext old_context; ListCell *lc; - UniqueRelInfo *uniqueRelInfo; - List *outer_exprs = NIL; - bool self_join = (extra_clauses != NULL); /* Certainly can't prove uniqueness when there are no joinclauses */ if (restrictlist == NIL) @@ -1269,28 +1191,17 @@ innerrel_is_unique_ext(PlannerInfo *root, /* * Query the cache to see if we've managed to prove that innerrel is - * unique for any subset of this outerrel. For non self-join search, we - * don't need an exact match, as extra outerrels can't make the innerrel - * any less unique (or more formally, the restrictlist for a join to a - * superset outerrel must be a superset of the conditions we successfully - * used before). For self-join search, we require an exact match of - * outerrels, because we need extra clauses to be valid for our case. - * Also, for self-join checking we've filtered the clauses list. Thus, - * for a self-join search, we can match only the result cached for another - * self-join check. + * unique for any subset of this outerrel. We don't need an exact match, + * as extra outerrels can't make the innerrel any less unique (or more + * formally, the restrictlist for a join to a superset outerrel must be a + * superset of the conditions we successfully used before). */ foreach(lc, innerrel->unique_for_rels) { - uniqueRelInfo = (UniqueRelInfo *) lfirst(lc); + Relids unique_for_rels = (Relids) lfirst(lc); - if ((!self_join && bms_is_subset(uniqueRelInfo->outerrelids, outerrelids)) || - (self_join && bms_equal(uniqueRelInfo->outerrelids, outerrelids) && - uniqueRelInfo->self_join)) - { - if (extra_clauses) - *extra_clauses = uniqueRelInfo->extra_clauses; + if (bms_is_subset(unique_for_rels, outerrelids)) return true; /* Success! */ - } } /* @@ -1307,8 +1218,7 @@ innerrel_is_unique_ext(PlannerInfo *root, /* No cached information, so try to make the proof. */ if (is_innerrel_unique_for(root, joinrelids, outerrelids, innerrel, - jointype, restrictlist, - self_join ? &outer_exprs : NULL)) + jointype, restrictlist)) { /* * Cache the positive result for future probes, being sure to keep it @@ -1321,16 +1231,10 @@ innerrel_is_unique_ext(PlannerInfo *root, * supersets of them anyway. */ old_context = MemoryContextSwitchTo(root->planner_cxt); - uniqueRelInfo = makeNode(UniqueRelInfo); - uniqueRelInfo->outerrelids = bms_copy(outerrelids); - uniqueRelInfo->self_join = self_join; - uniqueRelInfo->extra_clauses = outer_exprs; innerrel->unique_for_rels = lappend(innerrel->unique_for_rels, - uniqueRelInfo); + bms_copy(outerrelids)); MemoryContextSwitchTo(old_context); - if (extra_clauses) - *extra_clauses = outer_exprs; return true; /* Success! */ } else @@ -1376,8 +1280,7 @@ is_innerrel_unique_for(PlannerInfo *root, Relids outerrelids, RelOptInfo *innerrel, JoinType jointype, - List *restrictlist, - List **extra_clauses) + List *restrictlist) { List *clause_list = NIL; ListCell *lc; @@ -1407,1072 +1310,17 @@ is_innerrel_unique_for(PlannerInfo *root, continue; /* not mergejoinable */ /* - * Check if the clause has the form "outer op inner" or "inner op - * outer", and if so mark which side is inner. + * Check if clause has the form "outer op inner" or "inner op outer", + * and if so mark which side is inner. */ if (!clause_sides_match_join(restrictinfo, outerrelids, innerrel->relids)) continue; /* no good for these input relations */ - /* OK, add to the list */ + /* OK, add to list */ clause_list = lappend(clause_list, restrictinfo); } /* Let rel_is_distinct_for() do the hard work */ - return rel_is_distinct_for(root, innerrel, clause_list, extra_clauses); -} - -/* - * replace_varno - find in the given tree any Vars, PlaceHolderVar, and Relids - * that reference the removing relid, and change them to the reference to - * the replacement relid. - * - * NOTE: although this has the form of a walker, we cheat and modify the - * nodes in-place. - */ - -typedef struct -{ - int from; - int to; - int sublevels_up; -} ReplaceVarnoContext; - -static bool -replace_varno_walker(Node *node, ReplaceVarnoContext *ctx) -{ - if (node == NULL) - return false; - if (IsA(node, Var)) - { - Var *var = (Var *) node; - - if (var->varno == ctx->from && - var->varlevelsup == ctx->sublevels_up) - { - var->varno = ctx->to; - var->varnosyn = ctx->to; - } - return false; - } - else if (IsA(node, PlaceHolderVar)) - { - PlaceHolderVar *phv = (PlaceHolderVar *) node; - - if (phv->phlevelsup == ctx->sublevels_up) - { - phv->phrels = - replace_relid(phv->phrels, ctx->from, ctx->to); - phv->phnullingrels = - replace_relid(phv->phnullingrels, ctx->from, ctx->to); - } - - /* fall through to recurse into the placeholder's expression */ - } - else if (IsA(node, Query)) - { - /* Recurse into subselects */ - bool result; - - ctx->sublevels_up++; - result = query_tree_walker((Query *) node, - replace_varno_walker, - (void *) ctx, - QTW_EXAMINE_SORTGROUP); - ctx->sublevels_up--; - return result; - } - else if (IsA(node, RestrictInfo)) - { - RestrictInfo *rinfo = (RestrictInfo *) node; - int relid = -1; - bool is_req_equal = - (rinfo->required_relids == rinfo->clause_relids); - - if (bms_is_member(ctx->from, rinfo->clause_relids)) - { - replace_varno((Node *) rinfo->clause, ctx->from, ctx->to); - replace_varno((Node *) rinfo->orclause, ctx->from, ctx->to); - rinfo->clause_relids = - replace_relid(rinfo->clause_relids, ctx->from, ctx->to); - rinfo->left_relids = - replace_relid(rinfo->left_relids, ctx->from, ctx->to); - rinfo->right_relids = - replace_relid(rinfo->right_relids, ctx->from, ctx->to); - } - - if (is_req_equal) - rinfo->required_relids = rinfo->clause_relids; - else - rinfo->required_relids = - replace_relid(rinfo->required_relids, ctx->from, ctx->to); - - rinfo->outer_relids = - replace_relid(rinfo->outer_relids, ctx->from, ctx->to); - rinfo->incompatible_relids = - replace_relid(rinfo->incompatible_relids, ctx->from, ctx->to); - - if (rinfo->mergeopfamilies && - bms_get_singleton_member(rinfo->clause_relids, &relid) && - relid == ctx->to && IsA(rinfo->clause, OpExpr)) - { - Expr *leftOp; - Expr *rightOp; - - leftOp = (Expr *) get_leftop(rinfo->clause); - rightOp = (Expr *) get_rightop(rinfo->clause); - - if (leftOp != NULL && equal(leftOp, rightOp)) - { - NullTest *ntest = makeNode(NullTest); - - ntest->arg = leftOp; - ntest->nulltesttype = IS_NOT_NULL; - ntest->argisrow = false; - ntest->location = -1; - rinfo->clause = (Expr *) ntest; - rinfo->mergeopfamilies = NIL; - } - Assert(rinfo->orclause == NULL); - } - - return false; - } - - return expression_tree_walker(node, replace_varno_walker, - (void *) ctx); -} - -static void -replace_varno(Node *node, int from, int to) -{ - ReplaceVarnoContext ctx; - - if (to <= 0) - return; - - ctx.from = from; - ctx.to = to; - ctx.sublevels_up = 0; - - /* - * Must be prepared to start with a Query or a bare expression tree. - */ - query_or_expression_tree_walker(node, - replace_varno_walker, - (void *) &ctx, - QTW_EXAMINE_SORTGROUP); -} - -/* - * Substitute newId by oldId in relids. - * - * We must make a copy of the original Bitmapset before making any - * modifications, because the same pointer to it might be shared among - * different places. - */ -static Bitmapset * -replace_relid(Relids relids, int oldId, int newId) -{ - if (oldId < 0) - return relids; - - /* Delete relid without substitution. */ - if (newId < 0) - return bms_del_member(bms_copy(relids), oldId); - - /* Substitute newId for oldId. */ - if (bms_is_member(oldId, relids)) - return bms_add_member(bms_del_member(bms_copy(relids), oldId), newId); - - return relids; -} - -/* - * Update EC members to point to the remaining relation instead of the removed - * one, removing duplicates. - * - * Restriction clauses for base relations are already distributed to - * the respective baserestrictinfo lists (see - * generate_implied_equalities_for_column). The above code has already processed - * this list, and updated these clauses to reference the remaining - * relation, so we can skip them here based on their relids. - * - * Likewise, we have already processed the join clauses that join the - * removed relation to the remaining one. - * - * Finally, there are join clauses that join the removed relation to - * some third relation. We can't just delete the source clauses and - * regenerate them from the EC because the corresponding equality - * operators might be missing (see the handling of ec_broken). - * Therefore, we will update the references in the source clauses. - * - * Derived clauses can be generated again, so it is simpler to just - * delete them. - */ -static void -update_eclasses(EquivalenceClass *ec, int from, int to) -{ - List *new_members = NIL; - List *new_sources = NIL; - ListCell *lc; - ListCell *lc1; - - foreach(lc, ec->ec_members) - { - EquivalenceMember *em = lfirst_node(EquivalenceMember, lc); - bool is_redundant = false; - - if (!bms_is_member(from, em->em_relids)) - { - new_members = lappend(new_members, em); - continue; - } - - em->em_relids = replace_relid(em->em_relids, from, to); - em->em_jdomain->jd_relids = replace_relid(em->em_jdomain->jd_relids, from, to); - - /* We only process inner joins */ - replace_varno((Node *) em->em_expr, from, to); - - foreach(lc1, new_members) - { - EquivalenceMember *other = lfirst_node(EquivalenceMember, lc1); - - if (!equal(em->em_relids, other->em_relids)) - continue; - - if (equal(em->em_expr, other->em_expr)) - { - is_redundant = true; - break; - } - } - - if (!is_redundant) - new_members = lappend(new_members, em); - } - - list_free(ec->ec_members); - ec->ec_members = new_members; - - list_free(ec->ec_derives); - ec->ec_derives = NULL; - - /* Update EC source expressions */ - foreach(lc, ec->ec_sources) - { - RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc); - bool is_redundant = false; - - if (!bms_is_member(from, rinfo->required_relids)) - { - new_sources = lappend(new_sources, rinfo); - continue; - } - - replace_varno((Node *) rinfo, from, to); - - /* - * After switching the clause to the remaining relation, check it for - * redundancy with existing ones. We don't have to check for - * redundancy with derived clauses, because we've just deleted them. - */ - foreach(lc1, new_sources) - { - RestrictInfo *other = lfirst_node(RestrictInfo, lc1); - - if (!equal(rinfo->clause_relids, other->clause_relids)) - continue; - - if (equal(rinfo->clause, other->clause)) - { - is_redundant = true; - break; - } - } - - if (!is_redundant) - new_sources = lappend(new_sources, rinfo); - } - - list_free(ec->ec_sources); - ec->ec_sources = new_sources; - ec->ec_relids = replace_relid(ec->ec_relids, from, to); -} - -/* - * "Logically" compares two RestrictInfo's ignoring the 'rinfo_serial' field, - * which makes almost every RestrictInfo unique. This type of comparison is - * useful when removing duplicates while moving RestrictInfo's from removed - * relation to remaining relation during self-join elimination. - * - * XXX: In the future, we might remove the 'rinfo_serial' field completely and - * get rid of this function. - */ -static bool -restrict_infos_logically_equal(RestrictInfo *a, RestrictInfo *b) -{ - int saved_rinfo_serial = a->rinfo_serial; - bool result; - - a->rinfo_serial = b->rinfo_serial; - result = equal(a, b); - a->rinfo_serial = saved_rinfo_serial; - - return result; -} - -/* - * Remove a relation after we have proven that it participates only in an - * unneeded unique self join. - * - * Replace any links in planner info structures. - * - * Transfer join and restriction clauses from the removed relation to the - * remaining one. We change the Vars of the clause to point to the - * remaining relation instead of the removed one. The clauses that require - * a subset of joinrelids become restriction clauses of the remaining - * relation, and others remain join clauses. We append them to - * baserestrictinfo and joininfo respectively, trying not to introduce - * duplicates. - * - * We also have to process the 'joinclauses' list here, because it - * contains EC-derived join clauses which must become filter clauses. It - * is not enough to just correct the ECs because the EC-derived - * restrictions are generated before join removal (see - * generate_base_implied_equalities). - */ -static void -remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark, - RelOptInfo *toKeep, RelOptInfo *toRemove, - List *restrictlist) -{ - List *joininfos; - ListCell *lc; - int i; - List *jinfo_candidates = NIL; - List *binfo_candidates = NIL; - - Assert(toKeep->relid != -1); - - /* - * Replace the index of the removing table with the keeping one. The - * technique of removing/distributing restrictinfo is used here to attach - * just appeared (for keeping relation) join clauses and avoid adding - * duplicates of those that already exist in the joininfo list. - */ - joininfos = list_copy(toRemove->joininfo); - foreach(lc, joininfos) - { - RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc); - - remove_join_clause_from_rels(root, rinfo, rinfo->required_relids); - replace_varno((Node *) rinfo, toRemove->relid, toKeep->relid); - - if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE) - jinfo_candidates = lappend(jinfo_candidates, rinfo); - else - binfo_candidates = lappend(binfo_candidates, rinfo); - } - - /* - * Concatenate restrictlist to the list of base restrictions of the - * removing table just to simplify the replacement procedure: all of them - * weren't connected to any keeping relations and need to be added to some - * rels. - */ - toRemove->baserestrictinfo = list_concat(toRemove->baserestrictinfo, - restrictlist); - foreach(lc, toRemove->baserestrictinfo) - { - RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc); - - replace_varno((Node *) rinfo, toRemove->relid, toKeep->relid); - - if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE) - jinfo_candidates = lappend(jinfo_candidates, rinfo); - else - binfo_candidates = lappend(binfo_candidates, rinfo); - } - - /* - * Now, add all non-redundant clauses to the keeping relation. - * Contradictory operation. On the one side, we reduce the length of - * restrict lists that can impact planning or executing time. - * Additionally, we improve the accuracy of cardinality estimation. On the - * other side, it is one more place that can make planning time much - * longer in specific cases. It would have been better to avoid calling - * the equal() function here, but it's the only way to detect duplicated - * inequality expressions. - */ - foreach(lc, binfo_candidates) - { - RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc); - ListCell *olc = NULL; - bool is_redundant = false; - - Assert(!bms_is_member(toRemove->relid, rinfo->required_relids)); - - foreach(olc, toKeep->baserestrictinfo) - { - RestrictInfo *src = lfirst_node(RestrictInfo, olc); - - if (!bms_equal(src->clause_relids, rinfo->clause_relids)) - /* Const and non-const expressions can't be equal */ - continue; - - if (src == rinfo || - (rinfo->parent_ec != NULL - && src->parent_ec == rinfo->parent_ec) - || restrict_infos_logically_equal(rinfo, src)) - { - is_redundant = true; - break; - } - } - if (!is_redundant) - distribute_restrictinfo_to_rels(root, rinfo); - } - foreach(lc, jinfo_candidates) - { - RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc); - ListCell *olc = NULL; - bool is_redundant = false; - - Assert(!bms_is_member(toRemove->relid, rinfo->required_relids)); - - foreach(olc, toKeep->joininfo) - { - RestrictInfo *src = lfirst_node(RestrictInfo, olc); - - if (!bms_equal(src->clause_relids, rinfo->clause_relids)) - /* Can't compare trivially different clauses */ - continue; - - if (src == rinfo || - (rinfo->parent_ec != NULL - && src->parent_ec == rinfo->parent_ec) - || restrict_infos_logically_equal(rinfo, src)) - { - is_redundant = true; - break; - } - } - if (!is_redundant) - distribute_restrictinfo_to_rels(root, rinfo); - } - list_free(binfo_candidates); - list_free(jinfo_candidates); - - /* - * Arrange equivalence classes, mentioned removing a table, with the - * keeping one: varno of removing table should be replaced in members and - * sources lists. Also, remove duplicated elements if this replacement - * procedure created them. - */ - i = -1; - while ((i = bms_next_member(toRemove->eclass_indexes, i)) >= 0) - { - EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes, i); - - update_eclasses(ec, toRemove->relid, toKeep->relid); - toKeep->eclass_indexes = bms_add_member(toKeep->eclass_indexes, i); - } - - /* - * Transfer the targetlist and attr_needed flags. - */ - - foreach(lc, toRemove->reltarget->exprs) - { - Node *node = lfirst(lc); - - replace_varno(node, toRemove->relid, toKeep->relid); - if (!list_member(toKeep->reltarget->exprs, node)) - toKeep->reltarget->exprs = lappend(toKeep->reltarget->exprs, node); - } - - for (i = toKeep->min_attr; i <= toKeep->max_attr; i++) - { - int attno = i - toKeep->min_attr; - - toRemove->attr_needed[attno] = replace_relid(toRemove->attr_needed[attno], - toRemove->relid, toKeep->relid); - toKeep->attr_needed[attno] = bms_add_members(toKeep->attr_needed[attno], - toRemove->attr_needed[attno]); - } - - /* - * If the removed relation has a row mark, transfer it to the remaining - * one. - * - * If both rels have row marks, just keep the one corresponding to the - * remaining relation, because we verified earlier that they have the same - * strength. - */ - if (rmark) - { - if (kmark) - { - Assert(kmark->markType == rmark->markType); - - root->rowMarks = list_delete_ptr(root->rowMarks, rmark); - } - else - { - /* Shouldn't have inheritance children here. */ - Assert(rmark->rti == rmark->prti); - - rmark->rti = rmark->prti = toKeep->relid; - } - } - - /* Replace varno in all the query structures */ - replace_varno((Node *) root->parse, toRemove->relid, toKeep->relid); - - /* See remove_self_joins_one_group() */ - Assert(root->parse->resultRelation != toRemove->relid); - Assert(root->parse->resultRelation != toKeep->relid); - - /* Replace links in the planner info */ - remove_rel_from_query(root, toRemove, toKeep->relid, NULL, NULL); - - /* At last, replace varno in root targetlist and HAVING clause */ - replace_varno((Node *) root->processed_tlist, - toRemove->relid, toKeep->relid); - replace_varno((Node *) root->processed_groupClause, - toRemove->relid, toKeep->relid); - replace_relid(root->all_result_relids, toRemove->relid, toKeep->relid); - replace_relid(root->leaf_result_relids, toRemove->relid, toKeep->relid); - - - /* - * There may be references to the rel in root->fkey_list, but if so, - * match_foreign_keys_to_quals() will get rid of them. - */ - - /* - * Finally, remove the rel from the baserel array to prevent it from being - * referenced again. (We can't do this earlier because - * remove_join_clause_from_rels will touch it.) - */ - root->simple_rel_array[toRemove->relid] = NULL; - - /* And nuke the RelOptInfo, just in case there's another access path */ - pfree(toRemove); -} - -/* - * split_selfjoin_quals - * Processes 'joinquals' by building two lists: one containing the quals - * where the columns/exprs are on either side of the join match, and - * another one containing the remaining quals. - * - * 'joinquals' must only contain quals for a RTE_RELATION being joined to - * itself. - */ -static void -split_selfjoin_quals(PlannerInfo *root, List *joinquals, List **selfjoinquals, - List **otherjoinquals, int from, int to) -{ - ListCell *lc; - List *sjoinquals = NIL; - List *ojoinquals = NIL; - - foreach(lc, joinquals) - { - RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc); - OpExpr *expr; - Node *leftexpr; - Node *rightexpr; - - /* In general, clause looks like F(arg1) = G(arg2) */ - if (!rinfo->mergeopfamilies || - bms_num_members(rinfo->clause_relids) != 2 || - bms_membership(rinfo->left_relids) != BMS_SINGLETON || - bms_membership(rinfo->right_relids) != BMS_SINGLETON) - { - ojoinquals = lappend(ojoinquals, rinfo); - continue; - } - - expr = (OpExpr *) rinfo->clause; - - if (!IsA(expr, OpExpr) || list_length(expr->args) != 2) - { - ojoinquals = lappend(ojoinquals, rinfo); - continue; - } - - leftexpr = get_leftop(rinfo->clause); - rightexpr = copyObject(get_rightop(rinfo->clause)); - - if (leftexpr && IsA(leftexpr, RelabelType)) - leftexpr = (Node *) ((RelabelType *) leftexpr)->arg; - if (rightexpr && IsA(rightexpr, RelabelType)) - rightexpr = (Node *) ((RelabelType *) rightexpr)->arg; - - /* - * Quite an expensive operation, narrowing the use case. For example, - * when we have cast of the same var to different (but compatible) - * types. - */ - replace_varno(rightexpr, bms_singleton_member(rinfo->right_relids), - bms_singleton_member(rinfo->left_relids)); - - if (equal(leftexpr, rightexpr)) - sjoinquals = lappend(sjoinquals, rinfo); - else - ojoinquals = lappend(ojoinquals, rinfo); - } - - *selfjoinquals = sjoinquals; - *otherjoinquals = ojoinquals; -} - -/* - * Check for a case when uniqueness is at least partly derived from a - * baserestrictinfo clause. In this case, we have a chance to return only - * one row (if such clauses on both sides of SJ are equal) or nothing (if they - * are different). - */ -static bool -match_unique_clauses(PlannerInfo *root, RelOptInfo *outer, List *uclauses, - Index relid) -{ - ListCell *lc; - - foreach(lc, uclauses) - { - RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc); - Expr *clause; - Node *iclause; - Node *c1; - bool matched = false; - ListCell *olc; - - Assert(outer->relid > 0 && relid > 0); - - /* Only filters like f(R.x1,...,R.xN) == expr we should consider. */ - Assert(bms_is_empty(rinfo->left_relids) ^ - bms_is_empty(rinfo->right_relids)); - - clause = (Expr *) copyObject(rinfo->clause); - replace_varno((Node *) clause, relid, outer->relid); - - iclause = bms_is_empty(rinfo->left_relids) ? get_rightop(clause) : - get_leftop(clause); - c1 = bms_is_empty(rinfo->left_relids) ? get_leftop(clause) : - get_rightop(clause); - - /* - * Compare these left and right sides with the corresponding sides of - * the outer's filters. If no one is detected - return immediately. - */ - foreach(olc, outer->baserestrictinfo) - { - RestrictInfo *orinfo = lfirst_node(RestrictInfo, olc); - Node *oclause; - Node *c2; - - if (orinfo->mergeopfamilies == NIL) - /* Don't consider clauses which aren't similar to 'F(X)=G(Y)' */ - continue; - - Assert(is_opclause(orinfo->clause)); - - oclause = bms_is_empty(orinfo->left_relids) ? - get_rightop(orinfo->clause) : get_leftop(orinfo->clause); - c2 = (bms_is_empty(orinfo->left_relids) ? - get_leftop(orinfo->clause) : get_rightop(orinfo->clause)); - - if (equal(iclause, oclause) && equal(c1, c2)) - { - matched = true; - break; - } - } - - if (!matched) - return false; - } - - return true; -} - -/* - * Find and remove unique self joins in a group of base relations that have - * the same Oid. - * - * Returns a set of relids that were removed. - */ -static Relids -remove_self_joins_one_group(PlannerInfo *root, Relids relids) -{ - Relids result = NULL; - int k; /* Index of kept relation */ - int r = -1; /* Index of removed relation */ - - while ((r = bms_next_member(relids, r)) > 0) - { - RelOptInfo *inner = root->simple_rel_array[r]; - - /* - * We don't accept result relation as either source or target relation - * of SJE, because result relation has different behavior in - * EvalPlanQual() and RETURNING clause. - */ - if (root->parse->resultRelation == r) - continue; - - k = r; - - while ((k = bms_next_member(relids, k)) > 0) - { - Relids joinrelids = NULL; - RelOptInfo *outer = root->simple_rel_array[k]; - List *restrictlist; - List *selfjoinquals; - List *otherjoinquals; - ListCell *lc; - bool jinfo_check = true; - PlanRowMark *omark = NULL; - PlanRowMark *imark = NULL; - List *uclauses = NIL; - - if (root->parse->resultRelation == k) - continue; - - /* A sanity check: the relations have the same Oid. */ - Assert(root->simple_rte_array[k]->relid == - root->simple_rte_array[r]->relid); - - /* - * It is impossible to eliminate join of two relations if they - * belong to different rules of order. Otherwise planner can't be - * able to find any variants of correct query plan. - */ - foreach(lc, root->join_info_list) - { - SpecialJoinInfo *info = (SpecialJoinInfo *) lfirst(lc); - - if ((bms_is_member(k, info->syn_lefthand) ^ - bms_is_member(r, info->syn_lefthand)) || - (bms_is_member(k, info->syn_righthand) ^ - bms_is_member(r, info->syn_righthand))) - { - jinfo_check = false; - break; - } - } - if (!jinfo_check) - continue; - - /* - * Check Row Marks equivalence. We can't remove the join if the - * relations have row marks of different strength (e.g. one is - * locked FOR UPDATE and another just has ROW_MARK_REFERENCE for - * EvalPlanQual rechecking). - */ - foreach(lc, root->rowMarks) - { - PlanRowMark *rowMark = (PlanRowMark *) lfirst(lc); - - if (rowMark->rti == k) - { - Assert(imark == NULL); - imark = rowMark; - } - else if (rowMark->rti == r) - { - Assert(omark == NULL); - omark = rowMark; - } - - if (omark && imark) - break; - } - if (omark && imark && omark->markType != imark->markType) - continue; - - /* - * We only deal with base rels here, so their relids bitset - * contains only one member -- their relid. - */ - joinrelids = bms_add_member(joinrelids, r); - joinrelids = bms_add_member(joinrelids, k); - - /* - * PHVs should not impose any constraints on removing self joins. - */ - - /* - * At this stage, joininfo lists of inner and outer can contain - * only clauses, required for a superior outer join that can't - * influence this optimization. So, we can avoid to call the - * build_joinrel_restrictlist() routine. - */ - restrictlist = generate_join_implied_equalities(root, joinrelids, - inner->relids, - outer, NULL); - - /* - * Process restrictlist to separate the self join quals out of the - * other quals. e.g x = x goes to selfjoinquals and a = b to - * otherjoinquals. - */ - split_selfjoin_quals(root, restrictlist, &selfjoinquals, - &otherjoinquals, inner->relid, outer->relid); - - /* - * To enable SJE for the only degenerate case without any self - * join clauses at all, add baserestrictinfo to this list. The - * degenerate case works only if both sides have the same clause. - * So doesn't matter which side to add. - */ - selfjoinquals = list_concat(selfjoinquals, outer->baserestrictinfo); - - /* - * Determine if the inner table can duplicate outer rows. We must - * bypass the unique rel cache here since we're possibly using a - * subset of join quals. We can use 'force_cache' == true when all - * join quals are self-join quals. Otherwise, we could end up - * putting false negatives in the cache. - */ - if (!innerrel_is_unique_ext(root, joinrelids, inner->relids, - outer, JOIN_INNER, selfjoinquals, - list_length(otherjoinquals) == 0, - &uclauses)) - continue; - - /* - * We have proven that for both relations, the same unique index - * guarantees that there is at most one row where columns equal - * given values. These values must be the same for both relations, - * or else we won't match the same row on each side of the join. - */ - if (!match_unique_clauses(root, inner, uclauses, outer->relid)) - continue; - - /* - * We can remove either relation, so remove the inner one in order - * to simplify this loop. - */ - remove_self_join_rel(root, omark, imark, outer, inner, restrictlist); - - result = bms_add_member(result, r); - - /* We have removed the outer relation, try the next one. */ - break; - } - } - - return result; -} - -/* - * Gather indexes of base relations from the joinlist and try to eliminate self - * joins. - */ -static Relids -remove_self_joins_recurse(PlannerInfo *root, List *joinlist, Relids toRemove) -{ - ListCell *jl; - Relids relids = NULL; - SelfJoinCandidate *candidates = NULL; - int i; - int j; - int numRels; - - /* Collect indexes of base relations of the join tree */ - foreach(jl, joinlist) - { - Node *jlnode = (Node *) lfirst(jl); - - if (IsA(jlnode, RangeTblRef)) - { - RangeTblRef *ref = (RangeTblRef *) jlnode; - RangeTblEntry *rte = root->simple_rte_array[ref->rtindex]; - - /* - * We only care about base relations from which we select - * something. - */ - if (rte->rtekind == RTE_RELATION && - rte->relkind == RELKIND_RELATION && - root->simple_rel_array[ref->rtindex] != NULL) - { - Assert(!bms_is_member(ref->rtindex, relids)); - relids = bms_add_member(relids, ref->rtindex); - } - } - else if (IsA(jlnode, List)) - /* Recursively go inside the sub-joinlist */ - toRemove = remove_self_joins_recurse(root, (List *) jlnode, - toRemove); - else - elog(ERROR, "unrecognized joinlist node type: %d", - (int) nodeTag(jlnode)); - } - - numRels = bms_num_members(relids); - - /* Need at least two relations for the join */ - if (numRels < 2) - return toRemove; - - /* - * In order to find relations with the same oid we first build an array of - * candidates and then sort it by oid. - */ - candidates = (SelfJoinCandidate *) palloc(sizeof(SelfJoinCandidate) * - numRels); - i = -1; - j = 0; - while ((i = bms_next_member(relids, i)) >= 0) - { - candidates[j].relid = i; - candidates[j].reloid = root->simple_rte_array[i]->relid; - j++; - } - - qsort(candidates, numRels, sizeof(SelfJoinCandidate), - self_join_candidates_cmp); - - /* - * Iteratively form a group of relation indexes with the same oid and - * launch the routine that detects self-joins in this group and removes - * excessive range table entries. - * - * At the end of the iteration, exclude the group from the overall relids - * list. So each next iteration of the cycle will involve less and less - * value of relids. - */ - i = 0; - for (j = 1; j < numRels + 1; j++) - { - if (j == numRels || candidates[j].reloid != candidates[i].reloid) - { - if (j - i >= 2) - { - /* Create a group of relation indexes with the same oid */ - Relids group = NULL; - Relids removed; - - while (i < j) - { - group = bms_add_member(group, candidates[i].relid); - i++; - } - - relids = bms_del_members(relids, group); - - /* - * Try to remove self-joins from a group of identical entries. - * Make the next attempt iteratively - if something is deleted - * from a group, changes in clauses and equivalence classes - * can give us a chance to find more candidates. - */ - do - { - Assert(!bms_overlap(group, toRemove)); - removed = remove_self_joins_one_group(root, group); - toRemove = bms_add_members(toRemove, removed); - group = bms_del_members(group, removed); - } while (!bms_is_empty(removed) && - bms_membership(group) == BMS_MULTIPLE); - bms_free(removed); - bms_free(group); - } - else - { - /* Single relation, just remove it from the set */ - relids = bms_del_member(relids, candidates[i].relid); - i = j; - } - } - } - - Assert(bms_is_empty(relids)); - - return toRemove; -} - -/* - * Compare self-join candidates by their oids. - */ -static int -self_join_candidates_cmp(const void *a, const void *b) -{ - const SelfJoinCandidate *ca = (const SelfJoinCandidate *) a; - const SelfJoinCandidate *cb = (const SelfJoinCandidate *) b; - - if (ca->reloid != cb->reloid) - return (ca->reloid < cb->reloid ? -1 : 1); - else - return 0; -} - -/* - * Find and remove useless self joins. - * - * Search for joins where a relation is joined to itself. If the join clause - * for each tuple from one side of the join is proven to match the same - * physical row (or nothing) on the other side, that self-join can be - * eliminated from the query. Suitable join clauses are assumed to be in the - * form of X = X, and can be replaced with NOT NULL clauses. - * - * For the sake of simplicity, we don't apply this optimization to special - * joins. Here is a list of what we could do in some particular cases: - * 'a a1 semi join a a2': is reduced to inner by reduce_unique_semijoins, - * and then removed normally. - * 'a a1 anti join a a2': could simplify to a scan with 'outer quals AND - * (IS NULL on join columns OR NOT inner quals)'. - * 'a a1 left join a a2': could simplify to a scan like inner but without - * NOT NULL conditions on join columns. - * 'a a1 left join (a a2 join b)': can't simplify this, because join to b - * can both remove rows and introduce duplicates. - * - * To search for removable joins, we order all the relations on their Oid, - * go over each set with the same Oid, and consider each pair of relations - * in this set. - * - * To remove the join, we mark one of the participating relations as dead - * and rewrite all references to it to point to the remaining relation. - * This includes modifying RestrictInfos, EquivalenceClasses, and - * EquivalenceMembers. We also have to modify the row marks. The join clauses - * of the removed relation become either restriction or join clauses, based on - * whether they reference any relations not participating in the removed join. - * - * 'targetlist' is the top-level targetlist of the query. If it has any - * references to the removed relations, we update them to point to the - * remaining ones. - */ -List * -remove_useless_self_joins(PlannerInfo *root, List *joinlist) -{ - Relids toRemove = NULL; - int relid = -1; - - if (!enable_self_join_removal || joinlist == NIL || - (list_length(joinlist) == 1 && !IsA(linitial(joinlist), List))) - return joinlist; - - /* - * Merge pairs of relations participated in self-join. Remove unnecessary - * range table entries. - */ - toRemove = remove_self_joins_recurse(root, joinlist, toRemove); - - if (unlikely(toRemove != NULL)) - { - int nremoved = 0; - - /* At the end, remove orphaned relation links */ - while ((relid = bms_next_member(toRemove, relid)) >= 0) - joinlist = remove_rel_from_joinlist(joinlist, relid, &nremoved); - } - - return joinlist; + return rel_is_distinct_for(root, innerrel, clause_list); } |