/*------------------------------------------------------------------------- * * initsplan.c * Target list, qualification, joininfo initialization routines * * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * src/backend/optimizer/plan/initsplan.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include "catalog/pg_class.h" #include "catalog/pg_type.h" #include "nodes/makefuncs.h" #include "nodes/nodeFuncs.h" #include "optimizer/clauses.h" #include "optimizer/cost.h" #include "optimizer/inherit.h" #include "optimizer/joininfo.h" #include "optimizer/optimizer.h" #include "optimizer/pathnode.h" #include "optimizer/paths.h" #include "optimizer/placeholder.h" #include "optimizer/planmain.h" #include "optimizer/planner.h" #include "optimizer/prep.h" #include "optimizer/restrictinfo.h" #include "parser/analyze.h" #include "rewrite/rewriteManip.h" #include "utils/lsyscache.h" #include "utils/typcache.h" /* These parameters are set by GUC */ int from_collapse_limit; int join_collapse_limit; /* Elements of the postponed_qual_list used during deconstruct_recurse */ typedef struct PostponedQual { Node *qual; /* a qual clause waiting to be processed */ Relids relids; /* the set of baserels it references */ } PostponedQual; static void extract_lateral_references(PlannerInfo *root, RelOptInfo *brel, Index rtindex); static List *deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join, Relids *qualscope, Relids *inner_join_rels, List **postponed_qual_list); static void process_security_barrier_quals(PlannerInfo *root, int rti, Relids qualscope, bool below_outer_join); static SpecialJoinInfo *make_outerjoininfo(PlannerInfo *root, Relids left_rels, Relids right_rels, Relids inner_join_rels, JoinType jointype, List *clause); static void compute_semijoin_info(PlannerInfo *root, SpecialJoinInfo *sjinfo, List *clause); static void distribute_qual_to_rels(PlannerInfo *root, Node *clause, bool below_outer_join, JoinType jointype, Index security_level, Relids qualscope, Relids ojscope, Relids outerjoin_nonnullable, List **postponed_qual_list); static bool check_outerjoin_delay(PlannerInfo *root, Relids *relids_p, Relids *nullable_relids_p, bool is_pushed_down); static bool check_equivalence_delay(PlannerInfo *root, RestrictInfo *restrictinfo); static bool check_redundant_nullability_qual(PlannerInfo *root, Node *clause); static void check_mergejoinable(RestrictInfo *restrictinfo); static void check_hashjoinable(RestrictInfo *restrictinfo); static void check_memoizable(RestrictInfo *restrictinfo); /***************************************************************************** * * JOIN TREES * *****************************************************************************/ /* * add_base_rels_to_query * * Scan the query's jointree and create baserel RelOptInfos for all * the base relations (e.g., table, subquery, and function RTEs) * appearing in the jointree. * * The initial invocation must pass root->parse->jointree as the value of * jtnode. Internally, the function recurses through the jointree. * * At the end of this process, there should be one baserel RelOptInfo for * every non-join RTE that is used in the query. Some of the baserels * may be appendrel parents, which will require additional "otherrel" * RelOptInfos for their member rels, but those are added later. */ void add_base_rels_to_query(PlannerInfo *root, Node *jtnode) { if (jtnode == NULL) return; if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; (void) build_simple_rel(root, varno, NULL); } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; foreach(l, f->fromlist) add_base_rels_to_query(root, lfirst(l)); } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; add_base_rels_to_query(root, j->larg); add_base_rels_to_query(root, j->rarg); } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); } /* * add_other_rels_to_query * create "otherrel" RelOptInfos for the children of appendrel baserels * * At the end of this process, there should be RelOptInfos for all relations * that will be scanned by the query. */ void add_other_rels_to_query(PlannerInfo *root) { int rti; for (rti = 1; rti < root->simple_rel_array_size; rti++) { RelOptInfo *rel = root->simple_rel_array[rti]; RangeTblEntry *rte = root->simple_rte_array[rti]; /* there may be empty slots corresponding to non-baserel RTEs */ if (rel == NULL) continue; /* Ignore any "otherrels" that were already added. */ if (rel->reloptkind != RELOPT_BASEREL) continue; /* If it's marked as inheritable, look for children. */ if (rte->inh) expand_inherited_rtentry(root, rel, rte, rti); } } /***************************************************************************** * * TARGET LISTS * *****************************************************************************/ /* * build_base_rel_tlists * Add targetlist entries for each var needed in the query's final tlist * (and HAVING clause, if any) to the appropriate base relations. * * We mark such vars as needed by "relation 0" to ensure that they will * propagate up through all join plan steps. */ void build_base_rel_tlists(PlannerInfo *root, List *final_tlist) { List *tlist_vars = pull_var_clause((Node *) final_tlist, PVC_RECURSE_AGGREGATES | PVC_RECURSE_WINDOWFUNCS | PVC_INCLUDE_PLACEHOLDERS); if (tlist_vars != NIL) { add_vars_to_targetlist(root, tlist_vars, bms_make_singleton(0), true); list_free(tlist_vars); } /* * If there's a HAVING clause, we'll need the Vars it uses, too. Note * that HAVING can contain Aggrefs but not WindowFuncs. */ if (root->parse->havingQual) { List *having_vars = pull_var_clause(root->parse->havingQual, PVC_RECURSE_AGGREGATES | PVC_INCLUDE_PLACEHOLDERS); if (having_vars != NIL) { add_vars_to_targetlist(root, having_vars, bms_make_singleton(0), true); list_free(having_vars); } } } /* * add_vars_to_targetlist * For each variable appearing in the list, add it to the owning * relation's targetlist if not already present, and mark the variable * as being needed for the indicated join (or for final output if * where_needed includes "relation 0"). * * The list may also contain PlaceHolderVars. These don't necessarily * have a single owning relation; we keep their attr_needed info in * root->placeholder_list instead. If create_new_ph is true, it's OK * to create new PlaceHolderInfos; otherwise, the PlaceHolderInfos must * already exist, and we should only update their ph_needed. (This should * be true before deconstruct_jointree begins, and false after that.) */ void add_vars_to_targetlist(PlannerInfo *root, List *vars, Relids where_needed, bool create_new_ph) { ListCell *temp; Assert(!bms_is_empty(where_needed)); foreach(temp, vars) { Node *node = (Node *) lfirst(temp); if (IsA(node, Var)) { Var *var = (Var *) node; RelOptInfo *rel = find_base_rel(root, var->varno); int attno = var->varattno; if (bms_is_subset(where_needed, rel->relids)) continue; Assert(attno >= rel->min_attr && attno <= rel->max_attr); attno -= rel->min_attr; if (rel->attr_needed[attno] == NULL) { /* Variable not yet requested, so add to rel's targetlist */ /* XXX is copyObject necessary here? */ rel->reltarget->exprs = lappend(rel->reltarget->exprs, copyObject(var)); /* reltarget cost and width will be computed later */ } rel->attr_needed[attno] = bms_add_members(rel->attr_needed[attno], where_needed); } else if (IsA(node, PlaceHolderVar)) { PlaceHolderVar *phv = (PlaceHolderVar *) node; PlaceHolderInfo *phinfo = find_placeholder_info(root, phv, create_new_ph); phinfo->ph_needed = bms_add_members(phinfo->ph_needed, where_needed); } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node)); } } /***************************************************************************** * * LATERAL REFERENCES * *****************************************************************************/ /* * find_lateral_references * For each LATERAL subquery, extract all its references to Vars and * PlaceHolderVars of the current query level, and make sure those values * will be available for evaluation of the subquery. * * While later planning steps ensure that the Var/PHV source rels are on the * outside of nestloops relative to the LATERAL subquery, we also need to * ensure that the Vars/PHVs propagate up to the nestloop join level; this * means setting suitable where_needed values for them. * * Note that this only deals with lateral references in unflattened LATERAL * subqueries. When we flatten a LATERAL subquery, its lateral references * become plain Vars in the parent query, but they may have to be wrapped in * PlaceHolderVars if they need to be forced NULL by outer joins that don't * also null the LATERAL subquery. That's all handled elsewhere. * * This has to run before deconstruct_jointree, since it might result in * creation of PlaceHolderInfos. */ void find_lateral_references(PlannerInfo *root) { Index rti; /* We need do nothing if the query contains no LATERAL RTEs */ if (!root->hasLateralRTEs) return; /* * Examine all baserels (the rel array has been set up by now). */ for (rti = 1; rti < root->simple_rel_array_size; rti++) { RelOptInfo *brel = root->simple_rel_array[rti]; /* there may be empty slots corresponding to non-baserel RTEs */ if (brel == NULL) continue; Assert(brel->relid == rti); /* sanity check on array */ /* * This bit is less obvious than it might look. We ignore appendrel * otherrels and consider only their parent baserels. In a case where * a LATERAL-containing UNION ALL subquery was pulled up, it is the * otherrel that is actually going to be in the plan. However, we * want to mark all its lateral references as needed by the parent, * because it is the parent's relid that will be used for join * planning purposes. And the parent's RTE will contain all the * lateral references we need to know, since the pulled-up member is * nothing but a copy of parts of the original RTE's subquery. We * could visit the parent's children instead and transform their * references back to the parent's relid, but it would be much more * complicated for no real gain. (Important here is that the child * members have not yet received any processing beyond being pulled * up.) Similarly, in appendrels created by inheritance expansion, * it's sufficient to look at the parent relation. */ /* ignore RTEs that are "other rels" */ if (brel->reloptkind != RELOPT_BASEREL) continue; extract_lateral_references(root, brel, rti); } } static void extract_lateral_references(PlannerInfo *root, RelOptInfo *brel, Index rtindex) { RangeTblEntry *rte = root->simple_rte_array[rtindex]; List *vars; List *newvars; Relids where_needed; ListCell *lc; /* No cross-references are possible if it's not LATERAL */ if (!rte->lateral) return; /* Fetch the appropriate variables */ if (rte->rtekind == RTE_RELATION) vars = pull_vars_of_level((Node *) rte->tablesample, 0); else if (rte->rtekind == RTE_SUBQUERY) vars = pull_vars_of_level((Node *) rte->subquery, 1); else if (rte->rtekind == RTE_FUNCTION) vars = pull_vars_of_level((Node *) rte->functions, 0); else if (rte->rtekind == RTE_TABLEFUNC) vars = pull_vars_of_level((Node *) rte->tablefunc, 0); else if (rte->rtekind == RTE_VALUES) vars = pull_vars_of_level((Node *) rte->values_lists, 0); else { Assert(false); return; /* keep compiler quiet */ } if (vars == NIL) return; /* nothing to do */ /* Copy each Var (or PlaceHolderVar) and adjust it to match our level */ newvars = NIL; foreach(lc, vars) { Node *node = (Node *) lfirst(lc); node = copyObject(node); if (IsA(node, Var)) { Var *var = (Var *) node; /* Adjustment is easy since it's just one node */ var->varlevelsup = 0; } else if (IsA(node, PlaceHolderVar)) { PlaceHolderVar *phv = (PlaceHolderVar *) node; int levelsup = phv->phlevelsup; /* Have to work harder to adjust the contained expression too */ if (levelsup != 0) IncrementVarSublevelsUp(node, -levelsup, 0); /* * If we pulled the PHV out of a subquery RTE, its expression * needs to be preprocessed. subquery_planner() already did this * for level-zero PHVs in function and values RTEs, though. */ if (levelsup > 0) phv->phexpr = preprocess_phv_expression(root, phv->phexpr); } else Assert(false); newvars = lappend(newvars, node); } list_free(vars); /* * We mark the Vars as being "needed" at the LATERAL RTE. This is a bit * of a cheat: a more formal approach would be to mark each one as needed * at the join of the LATERAL RTE with its source RTE. But it will work, * and it's much less tedious than computing a separate where_needed for * each Var. */ where_needed = bms_make_singleton(rtindex); /* * Push Vars into their source relations' targetlists, and PHVs into * root->placeholder_list. */ add_vars_to_targetlist(root, newvars, where_needed, true); /* Remember the lateral references for create_lateral_join_info */ brel->lateral_vars = newvars; } /* * create_lateral_join_info * Fill in the per-base-relation direct_lateral_relids, lateral_relids * and lateral_referencers sets. * * This has to run after deconstruct_jointree, because we need to know the * final ph_eval_at values for PlaceHolderVars. */ void create_lateral_join_info(PlannerInfo *root) { bool found_laterals = false; Index rti; ListCell *lc; /* We need do nothing if the query contains no LATERAL RTEs */ if (!root->hasLateralRTEs) return; /* * Examine all baserels (the rel array has been set up by now). */ for (rti = 1; rti < root->simple_rel_array_size; rti++) { RelOptInfo *brel = root->simple_rel_array[rti]; Relids lateral_relids; /* there may be empty slots corresponding to non-baserel RTEs */ if (brel == NULL) continue; Assert(brel->relid == rti); /* sanity check on array */ /* ignore RTEs that are "other rels" */ if (brel->reloptkind != RELOPT_BASEREL) continue; lateral_relids = NULL; /* consider each laterally-referenced Var or PHV */ foreach(lc, brel->lateral_vars) { Node *node = (Node *) lfirst(lc); if (IsA(node, Var)) { Var *var = (Var *) node; found_laterals = true; lateral_relids = bms_add_member(lateral_relids, var->varno); } else if (IsA(node, PlaceHolderVar)) { PlaceHolderVar *phv = (PlaceHolderVar *) node; PlaceHolderInfo *phinfo = find_placeholder_info(root, phv, false); found_laterals = true; lateral_relids = bms_add_members(lateral_relids, phinfo->ph_eval_at); } else Assert(false); } /* We now have all the simple lateral refs from this rel */ brel->direct_lateral_relids = lateral_relids; brel->lateral_relids = bms_copy(lateral_relids); } /* * Now check for lateral references within PlaceHolderVars, and mark their * eval_at rels as having lateral references to the source rels. * * For a PHV that is due to be evaluated at a baserel, mark its source(s) * as direct lateral dependencies of the baserel (adding onto the ones * recorded above). If it's due to be evaluated at a join, mark its * source(s) as indirect lateral dependencies of each baserel in the join, * ie put them into lateral_relids but not direct_lateral_relids. This is * appropriate because we can't put any such baserel on the outside of a * join to one of the PHV's lateral dependencies, but on the other hand we * also can't yet join it directly to the dependency. */ foreach(lc, root->placeholder_list) { PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc); Relids eval_at = phinfo->ph_eval_at; int varno; if (phinfo->ph_lateral == NULL) continue; /* PHV is uninteresting if no lateral refs */ found_laterals = true; if (bms_get_singleton_member(eval_at, &varno)) { /* Evaluation site is a baserel */ RelOptInfo *brel = find_base_rel(root, varno); brel->direct_lateral_relids = bms_add_members(brel->direct_lateral_relids, phinfo->ph_lateral); brel->lateral_relids = bms_add_members(brel->lateral_relids, phinfo->ph_lateral); } else { /* Evaluation site is a join */ varno = -1; while ((varno = bms_next_member(eval_at, varno)) >= 0) { RelOptInfo *brel = find_base_rel(root, varno); brel->lateral_relids = bms_add_members(brel->lateral_relids, phinfo->ph_lateral); } } } /* * If we found no actual lateral references, we're done; but reset the * hasLateralRTEs flag to avoid useless work later. */ if (!found_laterals) { root->hasLateralRTEs = false; return; } /* * Calculate the transitive closure of the lateral_relids sets, so that * they describe both direct and indirect lateral references. If relation * X references Y laterally, and Y references Z laterally, then we will * have to scan X on the inside of a nestloop with Z, so for all intents * and purposes X is laterally dependent on Z too. * * This code is essentially Warshall's algorithm for transitive closure. * The outer loop considers each baserel, and propagates its lateral * dependencies to those baserels that have a lateral dependency on it. */ for (rti = 1; rti < root->simple_rel_array_size; rti++) { RelOptInfo *brel = root->simple_rel_array[rti]; Relids outer_lateral_relids; Index rti2; if (brel == NULL || brel->reloptkind != RELOPT_BASEREL) continue; /* need not consider baserel further if it has no lateral refs */ outer_lateral_relids = brel->lateral_relids; if (outer_lateral_relids == NULL) continue; /* else scan all baserels */ for (rti2 = 1; rti2 < root->simple_rel_array_size; rti2++) { RelOptInfo *brel2 = root->simple_rel_array[rti2]; if (brel2 == NULL || brel2->reloptkind != RELOPT_BASEREL) continue; /* if brel2 has lateral ref to brel, propagate brel's refs */ if (bms_is_member(rti, brel2->lateral_relids)) brel2->lateral_relids = bms_add_members(brel2->lateral_relids, outer_lateral_relids); } } /* * Now that we've identified all lateral references, mark each baserel * with the set of relids of rels that reference it laterally (possibly * indirectly) --- that is, the inverse mapping of lateral_relids. */ for (rti = 1; rti < root->simple_rel_array_size; rti++) { RelOptInfo *brel = root->simple_rel_array[rti]; Relids lateral_relids; int rti2; if (brel == NULL || brel->reloptkind != RELOPT_BASEREL) continue; /* Nothing to do at rels with no lateral refs */ lateral_relids = brel->lateral_relids; if (lateral_relids == NULL) continue; /* * We should not have broken the invariant that lateral_relids is * exactly NULL if empty. */ Assert(!bms_is_empty(lateral_relids)); /* Also, no rel should have a lateral dependency on itself */ Assert(!bms_is_member(rti, lateral_relids)); /* Mark this rel's referencees */ rti2 = -1; while ((rti2 = bms_next_member(lateral_relids, rti2)) >= 0) { RelOptInfo *brel2 = root->simple_rel_array[rti2]; Assert(brel2 != NULL && brel2->reloptkind == RELOPT_BASEREL); brel2->lateral_referencers = bms_add_member(brel2->lateral_referencers, rti); } } } /***************************************************************************** * * JOIN TREE PROCESSING * *****************************************************************************/ /* * deconstruct_jointree * Recursively scan the query's join tree for WHERE and JOIN/ON qual * clauses, and add these to the appropriate restrictinfo and joininfo * lists belonging to base RelOptInfos. Also, add SpecialJoinInfo nodes * to root->join_info_list for any outer joins appearing in the query tree. * Return a "joinlist" data structure showing the join order decisions * that need to be made by make_one_rel(). * * The "joinlist" result is a list of items that are either RangeTblRef * jointree nodes or sub-joinlists. All the items at the same level of * joinlist must be joined in an order to be determined by make_one_rel() * (note that legal orders may be constrained by SpecialJoinInfo nodes). * A sub-joinlist represents a subproblem to be planned separately. Currently * sub-joinlists arise only from FULL OUTER JOIN or when collapsing of * subproblems is stopped by join_collapse_limit or from_collapse_limit. * * NOTE: when dealing with inner joins, it is appropriate to let a qual clause * be evaluated at the lowest level where all the variables it mentions are * available. However, we cannot push a qual down into the nullable side(s) * of an outer join since the qual might eliminate matching rows and cause a * NULL row to be incorrectly emitted by the join. Therefore, we artificially * OR the minimum-relids of such an outer join into the required_relids of * clauses appearing above it. This forces those clauses to be delayed until * application of the outer join (or maybe even higher in the join tree). */ List * deconstruct_jointree(PlannerInfo *root) { List *result; Relids qualscope; Relids inner_join_rels; List *postponed_qual_list = NIL; /* Start recursion at top of jointree */ Assert(root->parse->jointree != NULL && IsA(root->parse->jointree, FromExpr)); /* this is filled as we scan the jointree */ root->nullable_baserels = NULL; result = deconstruct_recurse(root, (Node *) root->parse->jointree, false, &qualscope, &inner_join_rels, &postponed_qual_list); /* Shouldn't be any leftover quals */ Assert(postponed_qual_list == NIL); return result; } /* * deconstruct_recurse * One recursion level of deconstruct_jointree processing. * * Inputs: * jtnode is the jointree node to examine * below_outer_join is true if this node is within the nullable side of a * higher-level outer join * Outputs: * *qualscope gets the set of base Relids syntactically included in this * jointree node (do not modify or free this, as it may also be pointed * to by RestrictInfo and SpecialJoinInfo nodes) * *inner_join_rels gets the set of base Relids syntactically included in * inner joins appearing at or below this jointree node (do not modify * or free this, either) * *postponed_qual_list is a list of PostponedQual structs, which we can * add quals to if they turn out to belong to a higher join level * Return value is the appropriate joinlist for this jointree node * * In addition, entries will be added to root->join_info_list for outer joins. */ static List * deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join, Relids *qualscope, Relids *inner_join_rels, List **postponed_qual_list) { List *joinlist; if (jtnode == NULL) { *qualscope = NULL; *inner_join_rels = NULL; return NIL; } if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; /* qualscope is just the one RTE */ *qualscope = bms_make_singleton(varno); /* Deal with any securityQuals attached to the RTE */ if (root->qual_security_level > 0) process_security_barrier_quals(root, varno, *qualscope, below_outer_join); /* A single baserel does not create an inner join */ *inner_join_rels = NULL; joinlist = list_make1(jtnode); } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; List *child_postponed_quals = NIL; int remaining; ListCell *l; /* * First, recurse to handle child joins. We collapse subproblems into * a single joinlist whenever the resulting joinlist wouldn't exceed * from_collapse_limit members. Also, always collapse one-element * subproblems, since that won't lengthen the joinlist anyway. */ *qualscope = NULL; *inner_join_rels = NULL; joinlist = NIL; remaining = list_length(f->fromlist); foreach(l, f->fromlist) { Relids sub_qualscope; List *sub_joinlist; int sub_members; sub_joinlist = deconstruct_recurse(root, lfirst(l), below_outer_join, &sub_qualscope, inner_join_rels, &child_postponed_quals); *qualscope = bms_add_members(*qualscope, sub_qualscope); sub_members = list_length(sub_joinlist); remaining--; if (sub_members <= 1 || list_length(joinlist) + sub_members + remaining <= from_collapse_limit) joinlist = list_concat(joinlist, sub_joinlist); else joinlist = lappend(joinlist, sub_joinlist); } /* * A FROM with more than one list element is an inner join subsuming * all below it, so we should report inner_join_rels = qualscope. If * there was exactly one element, we should (and already did) report * whatever its inner_join_rels were. If there were no elements (is * that still possible?) the initialization before the loop fixed it. */ if (list_length(f->fromlist) > 1) *inner_join_rels = *qualscope; /* * Try to process any quals postponed by children. If they need * further postponement, add them to my output postponed_qual_list. */ foreach(l, child_postponed_quals) { PostponedQual *pq = (PostponedQual *) lfirst(l); if (bms_is_subset(pq->relids, *qualscope)) distribute_qual_to_rels(root, pq->qual, below_outer_join, JOIN_INNER, root->qual_security_level, *qualscope, NULL, NULL, NULL); else *postponed_qual_list = lappend(*postponed_qual_list, pq); } /* * Now process the top-level quals. */ foreach(l, (List *) f->quals) { Node *qual = (Node *) lfirst(l); distribute_qual_to_rels(root, qual, below_outer_join, JOIN_INNER, root->qual_security_level, *qualscope, NULL, NULL, postponed_qual_list); } } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; List *child_postponed_quals = NIL; Relids leftids, rightids, left_inners, right_inners, nonnullable_rels, nullable_rels, ojscope; List *leftjoinlist, *rightjoinlist; List *my_quals; SpecialJoinInfo *sjinfo; ListCell *l; /* * Order of operations here is subtle and critical. First we recurse * to handle sub-JOINs. Their join quals will be placed without * regard for whether this level is an outer join, which is correct. * Then we place our own join quals, which are restricted by lower * outer joins in any case, and are forced to this level if this is an * outer join and they mention the outer side. Finally, if this is an * outer join, we create a join_info_list entry for the join. This * will prevent quals above us in the join tree that use those rels * from being pushed down below this level. (It's okay for upper * quals to be pushed down to the outer side, however.) */ switch (j->jointype) { case JOIN_INNER: leftjoinlist = deconstruct_recurse(root, j->larg, below_outer_join, &leftids, &left_inners, &child_postponed_quals); rightjoinlist = deconstruct_recurse(root, j->rarg, below_outer_join, &rightids, &right_inners, &child_postponed_quals); *qualscope = bms_union(leftids, rightids); *inner_join_rels = *qualscope; /* Inner join adds no restrictions for quals */ nonnullable_rels = NULL; /* and it doesn't force anything to null, either */ nullable_rels = NULL; break; case JOIN_LEFT: case JOIN_ANTI: leftjoinlist = deconstruct_recurse(root, j->larg, below_outer_join, &leftids, &left_inners, &child_postponed_quals); rightjoinlist = deconstruct_recurse(root, j->rarg, true, &rightids, &right_inners, &child_postponed_quals); *qualscope = bms_union(leftids, rightids); *inner_join_rels = bms_union(left_inners, right_inners); nonnullable_rels = leftids; nullable_rels = rightids; break; case JOIN_SEMI: leftjoinlist = deconstruct_recurse(root, j->larg, below_outer_join, &leftids, &left_inners, &child_postponed_quals); rightjoinlist = deconstruct_recurse(root, j->rarg, below_outer_join, &rightids, &right_inners, &child_postponed_quals); *qualscope = bms_union(leftids, rightids); *inner_join_rels = bms_union(left_inners, right_inners); /* Semi join adds no restrictions for quals */ nonnullable_rels = NULL; /* * Theoretically, a semijoin would null the RHS; but since the * RHS can't be accessed above the join, this is immaterial * and we needn't account for it. */ nullable_rels = NULL; break; case JOIN_FULL: leftjoinlist = deconstruct_recurse(root, j->larg, true, &leftids, &left_inners, &child_postponed_quals); rightjoinlist = deconstruct_recurse(root, j->rarg, true, &rightids, &right_inners, &child_postponed_quals); *qualscope = bms_union(leftids, rightids); *inner_join_rels = bms_union(left_inners, right_inners); /* each side is both outer and inner */ nonnullable_rels = *qualscope; nullable_rels = *qualscope; break; default: /* JOIN_RIGHT was eliminated during reduce_outer_joins() */ elog(ERROR, "unrecognized join type: %d", (int) j->jointype); nonnullable_rels = NULL; /* keep compiler quiet */ nullable_rels = NULL; leftjoinlist = rightjoinlist = NIL; break; } /* Report all rels that will be nulled anywhere in the jointree */ root->nullable_baserels = bms_add_members(root->nullable_baserels, nullable_rels); /* * Try to process any quals postponed by children. If they need * further postponement, add them to my output postponed_qual_list. * Quals that can be processed now must be included in my_quals, so * that they'll be handled properly in make_outerjoininfo. */ my_quals = NIL; foreach(l, child_postponed_quals) { PostponedQual *pq = (PostponedQual *) lfirst(l); if (bms_is_subset(pq->relids, *qualscope)) my_quals = lappend(my_quals, pq->qual); else { /* * We should not be postponing any quals past an outer join. * If this Assert fires, pull_up_subqueries() messed up. */ Assert(j->jointype == JOIN_INNER); *postponed_qual_list = lappend(*postponed_qual_list, pq); } } my_quals = list_concat(my_quals, (List *) j->quals); /* * For an OJ, form the SpecialJoinInfo now, because we need the OJ's * semantic scope (ojscope) to pass to distribute_qual_to_rels. But * we mustn't add it to join_info_list just yet, because we don't want * distribute_qual_to_rels to think it is an outer join below us. * * Semijoins are a bit of a hybrid: we build a SpecialJoinInfo, but we * want ojscope = NULL for distribute_qual_to_rels. */ if (j->jointype != JOIN_INNER) { sjinfo = make_outerjoininfo(root, leftids, rightids, *inner_join_rels, j->jointype, my_quals); if (j->jointype == JOIN_SEMI) ojscope = NULL; else ojscope = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand); } else { sjinfo = NULL; ojscope = NULL; } /* Process the JOIN's qual clauses */ foreach(l, my_quals) { Node *qual = (Node *) lfirst(l); distribute_qual_to_rels(root, qual, below_outer_join, j->jointype, root->qual_security_level, *qualscope, ojscope, nonnullable_rels, postponed_qual_list); } /* Now we can add the SpecialJoinInfo to join_info_list */ if (sjinfo) { root->join_info_list = lappend(root->join_info_list, sjinfo); /* Each time we do that, recheck placeholder eval levels */ update_placeholder_eval_levels(root, sjinfo); } /* * Finally, compute the output joinlist. We fold subproblems together * except at a FULL JOIN or where join_collapse_limit would be * exceeded. */ if (j->jointype == JOIN_FULL) { /* force the join order exactly at this node */ joinlist = list_make1(list_make2(leftjoinlist, rightjoinlist)); } else if (list_length(leftjoinlist) + list_length(rightjoinlist) <= join_collapse_limit) { /* OK to combine subproblems */ joinlist = list_concat(leftjoinlist, rightjoinlist); } else { /* can't combine, but needn't force join order above here */ Node *leftpart, *rightpart; /* avoid creating useless 1-element sublists */ if (list_length(leftjoinlist) == 1) leftpart = (Node *) linitial(leftjoinlist); else leftpart = (Node *) leftjoinlist; if (list_length(rightjoinlist) == 1) rightpart = (Node *) linitial(rightjoinlist); else rightpart = (Node *) rightjoinlist; joinlist = list_make2(leftpart, rightpart); } } else { elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); joinlist = NIL; /* keep compiler quiet */ } return joinlist; } /* * process_security_barrier_quals * Transfer security-barrier quals into relation's baserestrictinfo list. * * The rewriter put any relevant security-barrier conditions into the RTE's * securityQuals field, but it's now time to copy them into the rel's * baserestrictinfo. * * In inheritance cases, we only consider quals attached to the parent rel * here; they will be valid for all children too, so it's okay to consider * them for purposes like equivalence class creation. Quals attached to * individual child rels will be dealt with during path creation. */ static void process_security_barrier_quals(PlannerInfo *root, int rti, Relids qualscope, bool below_outer_join) { RangeTblEntry *rte = root->simple_rte_array[rti]; Index security_level = 0; ListCell *lc; /* * Each element of the securityQuals list has been preprocessed into an * implicitly-ANDed list of clauses. All the clauses in a given sublist * should get the same security level, but successive sublists get higher * levels. */ foreach(lc, rte->securityQuals) { List *qualset = (List *) lfirst(lc); ListCell *lc2; foreach(lc2, qualset) { Node *qual = (Node *) lfirst(lc2); /* * We cheat to the extent of passing ojscope = qualscope rather * than its more logical value of NULL. The only effect this has * is to force a Var-free qual to be evaluated at the rel rather * than being pushed up to top of tree, which we don't want. */ distribute_qual_to_rels(root, qual, below_outer_join, JOIN_INNER, security_level, qualscope, qualscope, NULL, NULL); } security_level++; } /* Assert that qual_security_level is higher than anything we just used */ Assert(security_level <= root->qual_security_level); } /* * make_outerjoininfo * Build a SpecialJoinInfo for the current outer join * * Inputs: * left_rels: the base Relids syntactically on outer side of join * right_rels: the base Relids syntactically on inner side of join * inner_join_rels: base Relids participating in inner joins below this one * jointype: what it says (must always be LEFT, FULL, SEMI, or ANTI) * clause: the outer join's join condition (in implicit-AND format) * * The node should eventually be appended to root->join_info_list, but we * do not do that here. * * Note: we assume that this function is invoked bottom-up, so that * root->join_info_list already contains entries for all outer joins that are * syntactically below this one. */ static SpecialJoinInfo * make_outerjoininfo(PlannerInfo *root, Relids left_rels, Relids right_rels, Relids inner_join_rels, JoinType jointype, List *clause) { SpecialJoinInfo *sjinfo = makeNode(SpecialJoinInfo); Relids clause_relids; Relids strict_relids; Relids min_lefthand; Relids min_righthand; ListCell *l; /* * We should not see RIGHT JOIN here because left/right were switched * earlier */ Assert(jointype != JOIN_INNER); Assert(jointype != JOIN_RIGHT); /* * Presently the executor cannot support FOR [KEY] UPDATE/SHARE marking of * rels appearing on the nullable side of an outer join. (It's somewhat * unclear what that would mean, anyway: what should we mark when a result * row is generated from no element of the nullable relation?) So, * complain if any nullable rel is FOR [KEY] UPDATE/SHARE. * * You might be wondering why this test isn't made far upstream in the * parser. It's because the parser hasn't got enough info --- consider * FOR UPDATE applied to a view. Only after rewriting and flattening do * we know whether the view contains an outer join. * * We use the original RowMarkClause list here; the PlanRowMark list would * list everything. */ foreach(l, root->parse->rowMarks) { RowMarkClause *rc = (RowMarkClause *) lfirst(l); if (bms_is_member(rc->rti, right_rels) || (jointype == JOIN_FULL && bms_is_member(rc->rti, left_rels))) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), /*------ translator: %s is a SQL row locking clause such as FOR UPDATE */ errmsg("%s cannot be applied to the nullable side of an outer join", LCS_asString(rc->strength)))); } sjinfo->syn_lefthand = left_rels; sjinfo->syn_righthand = right_rels; sjinfo->jointype = jointype; /* this always starts out false */ sjinfo->delay_upper_joins = false; compute_semijoin_info(root, sjinfo, clause); /* If it's a full join, no need to be very smart */ if (jointype == JOIN_FULL) { sjinfo->min_lefthand = bms_copy(left_rels); sjinfo->min_righthand = bms_copy(right_rels); sjinfo->lhs_strict = false; /* don't care about this */ return sjinfo; } /* * Retrieve all relids mentioned within the join clause. */ clause_relids = pull_varnos(root, (Node *) clause); /* * For which relids is the clause strict, ie, it cannot succeed if the * rel's columns are all NULL? */ strict_relids = find_nonnullable_rels((Node *) clause); /* Remember whether the clause is strict for any LHS relations */ sjinfo->lhs_strict = bms_overlap(strict_relids, left_rels); /* * Required LHS always includes the LHS rels mentioned in the clause. We * may have to add more rels based on lower outer joins; see below. */ min_lefthand = bms_intersect(clause_relids, left_rels); /* * Similarly for required RHS. But here, we must also include any lower * inner joins, to ensure we don't try to commute with any of them. */ min_righthand = bms_int_members(bms_union(clause_relids, inner_join_rels), right_rels); /* * Now check previous outer joins for ordering restrictions. */ foreach(l, root->join_info_list) { SpecialJoinInfo *otherinfo = (SpecialJoinInfo *) lfirst(l); /* * A full join is an optimization barrier: we can't associate into or * out of it. Hence, if it overlaps either LHS or RHS of the current * rel, expand that side's min relset to cover the whole full join. */ if (otherinfo->jointype == JOIN_FULL) { if (bms_overlap(left_rels, otherinfo->syn_lefthand) || bms_overlap(left_rels, otherinfo->syn_righthand)) { min_lefthand = bms_add_members(min_lefthand, otherinfo->syn_lefthand); min_lefthand = bms_add_members(min_lefthand, otherinfo->syn_righthand); } if (bms_overlap(right_rels, otherinfo->syn_lefthand) || bms_overlap(right_rels, otherinfo->syn_righthand)) { min_righthand = bms_add_members(min_righthand, otherinfo->syn_lefthand); min_righthand = bms_add_members(min_righthand, otherinfo->syn_righthand); } /* Needn't do anything else with the full join */ continue; } /* * For a lower OJ in our LHS, if our join condition uses the lower * join's RHS and is not strict for that rel, we must preserve the * ordering of the two OJs, so add lower OJ's full syntactic relset to * min_lefthand. (We must use its full syntactic relset, not just its * min_lefthand + min_righthand. This is because there might be other * OJs below this one that this one can commute with, but we cannot * commute with them if we don't with this one.) Also, if the current * join is a semijoin or antijoin, we must preserve ordering * regardless of strictness. * * Note: I believe we have to insist on being strict for at least one * rel in the lower OJ's min_righthand, not its whole syn_righthand. */ if (bms_overlap(left_rels, otherinfo->syn_righthand)) { if (bms_overlap(clause_relids, otherinfo->syn_righthand) && (jointype == JOIN_SEMI || jointype == JOIN_ANTI || !bms_overlap(strict_relids, otherinfo->min_righthand))) { min_lefthand = bms_add_members(min_lefthand, otherinfo->syn_lefthand); min_lefthand = bms_add_members(min_lefthand, otherinfo->syn_righthand); } } /* * For a lower OJ in our RHS, if our join condition does not use the * lower join's RHS and the lower OJ's join condition is strict, we * can interchange the ordering of the two OJs; otherwise we must add * the lower OJ's full syntactic relset to min_righthand. * * Also, if our join condition does not use the lower join's LHS * either, force the ordering to be preserved. Otherwise we can end * up with SpecialJoinInfos with identical min_righthands, which can * confuse join_is_legal (see discussion in backend/optimizer/README). * * Also, we must preserve ordering anyway if either the current join * or the lower OJ is either a semijoin or an antijoin. * * Here, we have to consider that "our join condition" includes any * clauses that syntactically appeared above the lower OJ and below * ours; those are equivalent to degenerate clauses in our OJ and must * be treated as such. Such clauses obviously can't reference our * LHS, and they must be non-strict for the lower OJ's RHS (else * reduce_outer_joins would have reduced the lower OJ to a plain * join). Hence the other ways in which we handle clauses within our * join condition are not affected by them. The net effect is * therefore sufficiently represented by the delay_upper_joins flag * saved for us by check_outerjoin_delay. */ if (bms_overlap(right_rels, otherinfo->syn_righthand)) { if (bms_overlap(clause_relids, otherinfo->syn_righthand) || !bms_overlap(clause_relids, otherinfo->min_lefthand) || jointype == JOIN_SEMI || jointype == JOIN_ANTI || otherinfo->jointype == JOIN_SEMI || otherinfo->jointype == JOIN_ANTI || !otherinfo->lhs_strict || otherinfo->delay_upper_joins) { min_righthand = bms_add_members(min_righthand, otherinfo->syn_lefthand); min_righthand = bms_add_members(min_righthand, otherinfo->syn_righthand); } } } /* * Examine PlaceHolderVars. If a PHV is supposed to be evaluated within * this join's nullable side, then ensure that min_righthand contains the * full eval_at set of the PHV. This ensures that the PHV actually can be * evaluated within the RHS. Note that this works only because we should * already have determined the final eval_at level for any PHV * syntactically within this join. */ foreach(l, root->placeholder_list) { PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l); Relids ph_syn_level = phinfo->ph_var->phrels; /* Ignore placeholder if it didn't syntactically come from RHS */ if (!bms_is_subset(ph_syn_level, right_rels)) continue; /* Else, prevent join from being formed before we eval the PHV */ min_righthand = bms_add_members(min_righthand, phinfo->ph_eval_at); } /* * If we found nothing to put in min_lefthand, punt and make it the full * LHS, to avoid having an empty min_lefthand which will confuse later * processing. (We don't try to be smart about such cases, just correct.) * Likewise for min_righthand. */ if (bms_is_empty(min_lefthand)) min_lefthand = bms_copy(left_rels); if (bms_is_empty(min_righthand)) min_righthand = bms_copy(right_rels); /* Now they'd better be nonempty */ Assert(!bms_is_empty(min_lefthand)); Assert(!bms_is_empty(min_righthand)); /* Shouldn't overlap either */ Assert(!bms_overlap(min_lefthand, min_righthand)); sjinfo->min_lefthand = min_lefthand; sjinfo->min_righthand = min_righthand; return sjinfo; } /* * compute_semijoin_info * Fill semijoin-related fields of a new SpecialJoinInfo * * Note: this relies on only the jointype and syn_righthand fields of the * SpecialJoinInfo; the rest may not be set yet. */ static void compute_semijoin_info(PlannerInfo *root, SpecialJoinInfo *sjinfo, List *clause) { List *semi_operators; List *semi_rhs_exprs; bool all_btree; bool all_hash; ListCell *lc; /* Initialize semijoin-related fields in case we can't unique-ify */ sjinfo->semi_can_btree = false; sjinfo->semi_can_hash = false; sjinfo->semi_operators = NIL; sjinfo->semi_rhs_exprs = NIL; /* Nothing more to do if it's not a semijoin */ if (sjinfo->jointype != JOIN_SEMI) return; /* * Look to see whether the semijoin's join quals consist of AND'ed * equality operators, with (only) RHS variables on only one side of each * one. If so, we can figure out how to enforce uniqueness for the RHS. * * Note that the input clause list is the list of quals that are * *syntactically* associated with the semijoin, which in practice means * the synthesized comparison list for an IN or the WHERE of an EXISTS. * Particularly in the latter case, it might contain clauses that aren't * *semantically* associated with the join, but refer to just one side or * the other. We can ignore such clauses here, as they will just drop * down to be processed within one side or the other. (It is okay to * consider only the syntactically-associated clauses here because for a * semijoin, no higher-level quals could refer to the RHS, and so there * can be no other quals that are semantically associated with this join. * We do things this way because it is useful to have the set of potential * unique-ification expressions before we can extract the list of quals * that are actually semantically associated with the particular join.) * * Note that the semi_operators list consists of the joinqual operators * themselves (but commuted if needed to put the RHS value on the right). * These could be cross-type operators, in which case the operator * actually needed for uniqueness is a related single-type operator. We * assume here that that operator will be available from the btree or hash * opclass when the time comes ... if not, create_unique_plan() will fail. */ semi_operators = NIL; semi_rhs_exprs = NIL; all_btree = true; all_hash = enable_hashagg; /* don't consider hash if not enabled */ foreach(lc, clause) { OpExpr *op = (OpExpr *) lfirst(lc); Oid opno; Node *left_expr; Node *right_expr; Relids left_varnos; Relids right_varnos; Relids all_varnos; Oid opinputtype; /* Is it a binary opclause? */ if (!IsA(op, OpExpr) || list_length(op->args) != 2) { /* No, but does it reference both sides? */ all_varnos = pull_varnos(root, (Node *) op); if (!bms_overlap(all_varnos, sjinfo->syn_righthand) || bms_is_subset(all_varnos, sjinfo->syn_righthand)) { /* * Clause refers to only one rel, so ignore it --- unless it * contains volatile functions, in which case we'd better * punt. */ if (contain_volatile_functions((Node *) op)) return; continue; } /* Non-operator clause referencing both sides, must punt */ return; } /* Extract data from binary opclause */ opno = op->opno; left_expr = linitial(op->args); right_expr = lsecond(op->args); left_varnos = pull_varnos(root, left_expr); right_varnos = pull_varnos(root, right_expr); all_varnos = bms_union(left_varnos, right_varnos); opinputtype = exprType(left_expr); /* Does it reference both sides? */ if (!bms_overlap(all_varnos, sjinfo->syn_righthand) || bms_is_subset(all_varnos, sjinfo->syn_righthand)) { /* * Clause refers to only one rel, so ignore it --- unless it * contains volatile functions, in which case we'd better punt. */ if (contain_volatile_functions((Node *) op)) return; continue; } /* check rel membership of arguments */ if (!bms_is_empty(right_varnos) && bms_is_subset(right_varnos, sjinfo->syn_righthand) && !bms_overlap(left_varnos, sjinfo->syn_righthand)) { /* typical case, right_expr is RHS variable */ } else if (!bms_is_empty(left_varnos) && bms_is_subset(left_varnos, sjinfo->syn_righthand) && !bms_overlap(right_varnos, sjinfo->syn_righthand)) { /* flipped case, left_expr is RHS variable */ opno = get_commutator(opno); if (!OidIsValid(opno)) return; right_expr = left_expr; } else { /* mixed membership of args, punt */ return; } /* all operators must be btree equality or hash equality */ if (all_btree) { /* oprcanmerge is considered a hint... */ if (!op_mergejoinable(opno, opinputtype) || get_mergejoin_opfamilies(opno) == NIL) all_btree = false; } if (all_hash) { /* ... but oprcanhash had better be correct */ if (!op_hashjoinable(opno, opinputtype)) all_hash = false; } if (!(all_btree || all_hash)) return; /* so far so good, keep building lists */ semi_operators = lappend_oid(semi_operators, opno); semi_rhs_exprs = lappend(semi_rhs_exprs, copyObject(right_expr)); } /* Punt if we didn't find at least one column to unique-ify */ if (semi_rhs_exprs == NIL) return; /* * The expressions we'd need to unique-ify mustn't be volatile. */ if (contain_volatile_functions((Node *) semi_rhs_exprs)) return; /* * If we get here, we can unique-ify the semijoin's RHS using at least one * of sorting and hashing. Save the information about how to do that. */ sjinfo->semi_can_btree = all_btree; sjinfo->semi_can_hash = all_hash; sjinfo->semi_operators = semi_operators; sjinfo->semi_rhs_exprs = semi_rhs_exprs; } /***************************************************************************** * * QUALIFICATIONS * *****************************************************************************/ /* * distribute_qual_to_rels * Add clause information to either the baserestrictinfo or joininfo list * (depending on whether the clause is a join) of each base relation * mentioned in the clause. A RestrictInfo node is created and added to * the appropriate list for each rel. Alternatively, if the clause uses a * mergejoinable operator and is not delayed by outer-join rules, enter * the left- and right-side expressions into the query's list of * EquivalenceClasses. Alternatively, if the clause needs to be treated * as belonging to a higher join level, just add it to postponed_qual_list. * * 'clause': the qual clause to be distributed * 'below_outer_join': true if the qual is from a JOIN/ON that is below the * nullable side of a higher-level outer join * 'jointype': type of join the qual is from (JOIN_INNER for a WHERE clause) * 'security_level': security_level to assign to the qual * 'qualscope': set of baserels the qual's syntactic scope covers * 'ojscope': NULL if not an outer-join qual, else the minimum set of baserels * needed to form this join * 'outerjoin_nonnullable': NULL if not an outer-join qual, else the set of * baserels appearing on the outer (nonnullable) side of the join * (for FULL JOIN this includes both sides of the join, and must in fact * equal qualscope) * 'postponed_qual_list': list of PostponedQual structs, which we can add * this qual to if it turns out to belong to a higher join level. * Can be NULL if caller knows postponement is impossible. * * 'qualscope' identifies what level of JOIN the qual came from syntactically. * 'ojscope' is needed if we decide to force the qual up to the outer-join * level, which will be ojscope not necessarily qualscope. * * At the time this is called, root->join_info_list must contain entries for * all and only those special joins that are syntactically below this qual. */ static void distribute_qual_to_rels(PlannerInfo *root, Node *clause, bool below_outer_join, JoinType jointype, Index security_level, Relids qualscope, Relids ojscope, Relids outerjoin_nonnullable, List **postponed_qual_list) { Relids relids; bool is_pushed_down; bool outerjoin_delayed; bool pseudoconstant = false; bool maybe_equivalence; bool maybe_outer_join; Relids nullable_relids; RestrictInfo *restrictinfo; /* * Retrieve all relids mentioned within the clause. */ relids = pull_varnos(root, clause); /* * In ordinary SQL, a WHERE or JOIN/ON clause can't reference any rels * that aren't within its syntactic scope; however, if we pulled up a * LATERAL subquery then we might find such references in quals that have * been pulled up. We need to treat such quals as belonging to the join * level that includes every rel they reference. Although we could make * pull_up_subqueries() place such quals correctly to begin with, it's * easier to handle it here. When we find a clause that contains Vars * outside its syntactic scope, we add it to the postponed-quals list, and * process it once we've recursed back up to the appropriate join level. */ if (!bms_is_subset(relids, qualscope)) { PostponedQual *pq = (PostponedQual *) palloc(sizeof(PostponedQual)); Assert(root->hasLateralRTEs); /* shouldn't happen otherwise */ Assert(jointype == JOIN_INNER); /* mustn't postpone past outer join */ pq->qual = clause; pq->relids = relids; *postponed_qual_list = lappend(*postponed_qual_list, pq); return; } /* * If it's an outer-join clause, also check that relids is a subset of * ojscope. (This should not fail if the syntactic scope check passed.) */ if (ojscope && !bms_is_subset(relids, ojscope)) elog(ERROR, "JOIN qualification cannot refer to other relations"); /* * If the clause is variable-free, our normal heuristic for pushing it * down to just the mentioned rels doesn't work, because there are none. * * If the clause is an outer-join clause, we must force it to the OJ's * semantic level to preserve semantics. * * Otherwise, when the clause contains volatile functions, we force it to * be evaluated at its original syntactic level. This preserves the * expected semantics. * * When the clause contains no volatile functions either, it is actually a * pseudoconstant clause that will not change value during any one * execution of the plan, and hence can be used as a one-time qual in a * gating Result plan node. We put such a clause into the regular * RestrictInfo lists for the moment, but eventually createplan.c will * pull it out and make a gating Result node immediately above whatever * plan node the pseudoconstant clause is assigned to. It's usually best * to put a gating node as high in the plan tree as possible. If we are * not below an outer join, we can actually push the pseudoconstant qual * all the way to the top of the tree. If we are below an outer join, we * leave the qual at its original syntactic level (we could push it up to * just below the outer join, but that seems more complex than it's * worth). */ if (bms_is_empty(relids)) { if (ojscope) { /* clause is attached to outer join, eval it there */ relids = bms_copy(ojscope); /* mustn't use as gating qual, so don't mark pseudoconstant */ } else { /* eval at original syntactic level */ relids = bms_copy(qualscope); if (!contain_volatile_functions(clause)) { /* mark as gating qual */ pseudoconstant = true; /* tell createplan.c to check for gating quals */ root->hasPseudoConstantQuals = true; /* if not below outer join, push it to top of tree */ if (!below_outer_join) { relids = get_relids_in_jointree((Node *) root->parse->jointree, false); qualscope = bms_copy(relids); } } } } /*---------- * Check to see if clause application must be delayed by outer-join * considerations. * * A word about is_pushed_down: we mark the qual as "pushed down" if * it is (potentially) applicable at a level different from its original * syntactic level. This flag is used to distinguish OUTER JOIN ON quals * from other quals pushed down to the same joinrel. The rules are: * WHERE quals and INNER JOIN quals: is_pushed_down = true. * Non-degenerate OUTER JOIN quals: is_pushed_down = false. * Degenerate OUTER JOIN quals: is_pushed_down = true. * A "degenerate" OUTER JOIN qual is one that doesn't mention the * non-nullable side, and hence can be pushed down into the nullable side * without changing the join result. It is correct to treat it as a * regular filter condition at the level where it is evaluated. * * Note: it is not immediately obvious that a simple boolean is enough * for this: if for some reason we were to attach a degenerate qual to * its original join level, it would need to be treated as an outer join * qual there. However, this cannot happen, because all the rels the * clause mentions must be in the outer join's min_righthand, therefore * the join it needs must be formed before the outer join; and we always * attach quals to the lowest level where they can be evaluated. But * if we were ever to re-introduce a mechanism for delaying evaluation * of "expensive" quals, this area would need work. * * Note: generally, use of is_pushed_down has to go through the macro * RINFO_IS_PUSHED_DOWN, because that flag alone is not always sufficient * to tell whether a clause must be treated as pushed-down in context. * This seems like another reason why it should perhaps be rethought. *---------- */ if (bms_overlap(relids, outerjoin_nonnullable)) { /* * The qual is attached to an outer join and mentions (some of the) * rels on the nonnullable side, so it's not degenerate. * * We can't use such a clause to deduce equivalence (the left and * right sides might be unequal above the join because one of them has * gone to NULL) ... but we might be able to use it for more limited * deductions, if it is mergejoinable. So consider adding it to the * lists of set-aside outer-join clauses. */ is_pushed_down = false; maybe_equivalence = false; maybe_outer_join = true; /* Check to see if must be delayed by lower outer join */ outerjoin_delayed = check_outerjoin_delay(root, &relids, &nullable_relids, false); /* * Now force the qual to be evaluated exactly at the level of joining * corresponding to the outer join. We cannot let it get pushed down * into the nonnullable side, since then we'd produce no output rows, * rather than the intended single null-extended row, for any * nonnullable-side rows failing the qual. * * (Do this step after calling check_outerjoin_delay, because that * trashes relids.) */ Assert(ojscope); relids = ojscope; Assert(!pseudoconstant); } else { /* * Normal qual clause or degenerate outer-join clause. Either way, we * can mark it as pushed-down. */ is_pushed_down = true; /* Check to see if must be delayed by lower outer join */ outerjoin_delayed = check_outerjoin_delay(root, &relids, &nullable_relids, true); if (outerjoin_delayed) { /* Should still be a subset of current scope ... */ Assert(root->hasLateralRTEs || bms_is_subset(relids, qualscope)); Assert(ojscope == NULL || bms_is_subset(relids, ojscope)); /* * Because application of the qual will be delayed by outer join, * we mustn't assume its vars are equal everywhere. */ maybe_equivalence = false; /* * It's possible that this is an IS NULL clause that's redundant * with a lower antijoin; if so we can just discard it. We need * not test in any of the other cases, because this will only be * possible for pushed-down, delayed clauses. */ if (check_redundant_nullability_qual(root, clause)) return; } else { /* * Qual is not delayed by any lower outer-join restriction, so we * can consider feeding it to the equivalence machinery. However, * if it's itself within an outer-join clause, treat it as though * it appeared below that outer join (note that we can only get * here when the clause references only nullable-side rels). */ maybe_equivalence = true; if (outerjoin_nonnullable != NULL) below_outer_join = true; } /* * Since it doesn't mention the LHS, it's certainly not useful as a * set-aside OJ clause, even if it's in an OJ. */ maybe_outer_join = false; } /* * Build the RestrictInfo node itself. */ restrictinfo = make_restrictinfo(root, (Expr *) clause, is_pushed_down, outerjoin_delayed, pseudoconstant, security_level, relids, outerjoin_nonnullable, nullable_relids); /* * If it's a join clause (either naturally, or because delayed by * outer-join rules), add vars used in the clause to targetlists of their * relations, so that they will be emitted by the plan nodes that scan * those relations (else they won't be available at the join node!). * * Note: if the clause gets absorbed into an EquivalenceClass then this * may be unnecessary, but for now we have to do it to cover the case * where the EC becomes ec_broken and we end up reinserting the original * clauses into the plan. */ if (bms_membership(relids) == BMS_MULTIPLE) { List *vars = pull_var_clause(clause, PVC_RECURSE_AGGREGATES | PVC_RECURSE_WINDOWFUNCS | PVC_INCLUDE_PLACEHOLDERS); add_vars_to_targetlist(root, vars, relids, false); list_free(vars); } /* * We check "mergejoinability" of every clause, not only join clauses, * because we want to know about equivalences between vars of the same * relation, or between vars and consts. */ check_mergejoinable(restrictinfo); /* * If it is a true equivalence clause, send it to the EquivalenceClass * machinery. We do *not* attach it directly to any restriction or join * lists. The EC code will propagate it to the appropriate places later. * * If the clause has a mergejoinable operator and is not * outerjoin-delayed, yet isn't an equivalence because it is an outer-join * clause, the EC code may yet be able to do something with it. We add it * to appropriate lists for further consideration later. Specifically: * * If it is a left or right outer-join qualification that relates the two * sides of the outer join (no funny business like leftvar1 = leftvar2 + * rightvar), we add it to root->left_join_clauses or * root->right_join_clauses according to which side the nonnullable * variable appears on. * * If it is a full outer-join qualification, we add it to * root->full_join_clauses. (Ideally we'd discard cases that aren't * leftvar = rightvar, as we do for left/right joins, but this routine * doesn't have the info needed to do that; and the current usage of the * full_join_clauses list doesn't require that, so it's not currently * worth complicating this routine's API to make it possible.) * * If none of the above hold, pass it off to * distribute_restrictinfo_to_rels(). * * In all cases, it's important to initialize the left_ec and right_ec * fields of a mergejoinable clause, so that all possibly mergejoinable * expressions have representations in EquivalenceClasses. If * process_equivalence is successful, it will take care of that; * otherwise, we have to call initialize_mergeclause_eclasses to do it. */ if (restrictinfo->mergeopfamilies) { if (maybe_equivalence) { if (check_equivalence_delay(root, restrictinfo) && process_equivalence(root, &restrictinfo, below_outer_join)) return; /* EC rejected it, so set left_ec/right_ec the hard way ... */ if (restrictinfo->mergeopfamilies) /* EC might have changed this */ initialize_mergeclause_eclasses(root, restrictinfo); /* ... and fall through to distribute_restrictinfo_to_rels */ } else if (maybe_outer_join && restrictinfo->can_join) { /* we need to set up left_ec/right_ec the hard way */ initialize_mergeclause_eclasses(root, restrictinfo); /* now see if it should go to any outer-join lists */ if (bms_is_subset(restrictinfo->left_relids, outerjoin_nonnullable) && !bms_overlap(restrictinfo->right_relids, outerjoin_nonnullable)) { /* we have outervar = innervar */ root->left_join_clauses = lappend(root->left_join_clauses, restrictinfo); return; } if (bms_is_subset(restrictinfo->right_relids, outerjoin_nonnullable) && !bms_overlap(restrictinfo->left_relids, outerjoin_nonnullable)) { /* we have innervar = outervar */ root->right_join_clauses = lappend(root->right_join_clauses, restrictinfo); return; } if (jointype == JOIN_FULL) { /* FULL JOIN (above tests cannot match in this case) */ root->full_join_clauses = lappend(root->full_join_clauses, restrictinfo); return; } /* nope, so fall through to distribute_restrictinfo_to_rels */ } else { /* we still need to set up left_ec/right_ec */ initialize_mergeclause_eclasses(root, restrictinfo); } } /* No EC special case applies, so push it into the clause lists */ distribute_restrictinfo_to_rels(root, restrictinfo); } /* * check_outerjoin_delay * Detect whether a qual referencing the given relids must be delayed * in application due to the presence of a lower outer join, and/or * may force extra delay of higher-level outer joins. * * If the qual must be delayed, add relids to *relids_p to reflect the lowest * safe level for evaluating the qual, and return true. Any extra delay for * higher-level joins is reflected by setting delay_upper_joins to true in * SpecialJoinInfo structs. We also compute nullable_relids, the set of * referenced relids that are nullable by lower outer joins (note that this * can be nonempty even for a non-delayed qual). * * For an is_pushed_down qual, we can evaluate the qual as soon as (1) we have * all the rels it mentions, and (2) we are at or above any outer joins that * can null any of these rels and are below the syntactic location of the * given qual. We must enforce (2) because pushing down such a clause below * the OJ might cause the OJ to emit null-extended rows that should not have * been formed, or that should have been rejected by the clause. (This is * only an issue for non-strict quals, since if we can prove a qual mentioning * only nullable rels is strict, we'd have reduced the outer join to an inner * join in reduce_outer_joins().) * * To enforce (2), scan the join_info_list and merge the required-relid sets of * any such OJs into the clause's own reference list. At the time we are * called, the join_info_list contains only outer joins below this qual. We * have to repeat the scan until no new relids get added; this ensures that * the qual is suitably delayed regardless of the order in which OJs get * executed. As an example, if we have one OJ with LHS=A, RHS=B, and one with * LHS=B, RHS=C, it is implied that these can be done in either order; if the * B/C join is done first then the join to A can null C, so a qual actually * mentioning only C cannot be applied below the join to A. * * For a non-pushed-down qual, this isn't going to determine where we place the * qual, but we need to determine outerjoin_delayed and nullable_relids anyway * for use later in the planning process. * * Lastly, a pushed-down qual that references the nullable side of any current * join_info_list member and has to be evaluated above that OJ (because its * required relids overlap the LHS too) causes that OJ's delay_upper_joins * flag to be set true. This will prevent any higher-level OJs from * being interchanged with that OJ, which would result in not having any * correct place to evaluate the qual. (The case we care about here is a * sub-select WHERE clause within the RHS of some outer join. The WHERE * clause must effectively be treated as a degenerate clause of that outer * join's condition. Rather than trying to match such clauses with joins * directly, we set delay_upper_joins here, and when the upper outer join * is processed by make_outerjoininfo, it will refrain from allowing the * two OJs to commute.) */ static bool check_outerjoin_delay(PlannerInfo *root, Relids *relids_p, /* in/out parameter */ Relids *nullable_relids_p, /* output parameter */ bool is_pushed_down) { Relids relids; Relids nullable_relids; bool outerjoin_delayed; bool found_some; /* fast path if no special joins */ if (root->join_info_list == NIL) { *nullable_relids_p = NULL; return false; } /* must copy relids because we need the original value at the end */ relids = bms_copy(*relids_p); nullable_relids = NULL; outerjoin_delayed = false; do { ListCell *l; found_some = false; foreach(l, root->join_info_list) { SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l); /* do we reference any nullable rels of this OJ? */ if (bms_overlap(relids, sjinfo->min_righthand) || (sjinfo->jointype == JOIN_FULL && bms_overlap(relids, sjinfo->min_lefthand))) { /* yes; have we included all its rels in relids? */ if (!bms_is_subset(sjinfo->min_lefthand, relids) || !bms_is_subset(sjinfo->min_righthand, relids)) { /* no, so add them in */ relids = bms_add_members(relids, sjinfo->min_lefthand); relids = bms_add_members(relids, sjinfo->min_righthand); outerjoin_delayed = true; /* we'll need another iteration */ found_some = true; } /* track all the nullable rels of relevant OJs */ nullable_relids = bms_add_members(nullable_relids, sjinfo->min_righthand); if (sjinfo->jointype == JOIN_FULL) nullable_relids = bms_add_members(nullable_relids, sjinfo->min_lefthand); /* set delay_upper_joins if needed */ if (is_pushed_down && sjinfo->jointype != JOIN_FULL && bms_overlap(relids, sjinfo->min_lefthand)) sjinfo->delay_upper_joins = true; } } } while (found_some); /* identify just the actually-referenced nullable rels */ nullable_relids = bms_int_members(nullable_relids, *relids_p); /* replace *relids_p, and return nullable_relids */ bms_free(*relids_p); *relids_p = relids; *nullable_relids_p = nullable_relids; return outerjoin_delayed; } /* * check_equivalence_delay * Detect whether a potential equivalence clause is rendered unsafe * by outer-join-delay considerations. Return true if it's safe. * * The initial tests in distribute_qual_to_rels will consider a mergejoinable * clause to be a potential equivalence clause if it is not outerjoin_delayed. * But since the point of equivalence processing is that we will recombine the * two sides of the clause with others, we have to check that each side * satisfies the not-outerjoin_delayed condition on its own; otherwise it might * not be safe to evaluate everywhere we could place a derived equivalence * condition. */ static bool check_equivalence_delay(PlannerInfo *root, RestrictInfo *restrictinfo) { Relids relids; Relids nullable_relids; /* fast path if no special joins */ if (root->join_info_list == NIL) return true; /* must copy restrictinfo's relids to avoid changing it */ relids = bms_copy(restrictinfo->left_relids); /* check left side does not need delay */ if (check_outerjoin_delay(root, &relids, &nullable_relids, true)) return false; /* and similarly for the right side */ relids = bms_copy(restrictinfo->right_relids); if (check_outerjoin_delay(root, &relids, &nullable_relids, true)) return false; return true; } /* * check_redundant_nullability_qual * Check to see if the qual is an IS NULL qual that is redundant with * a lower JOIN_ANTI join. * * We want to suppress redundant IS NULL quals, not so much to save cycles * as to avoid generating bogus selectivity estimates for them. So if * redundancy is detected here, distribute_qual_to_rels() just throws away * the qual. */ static bool check_redundant_nullability_qual(PlannerInfo *root, Node *clause) { Var *forced_null_var; Index forced_null_rel; ListCell *lc; /* Check for IS NULL, and identify the Var forced to NULL */ forced_null_var = find_forced_null_var(clause); if (forced_null_var == NULL) return false; forced_null_rel = forced_null_var->varno; /* * If the Var comes from the nullable side of a lower antijoin, the IS * NULL condition is necessarily true. */ foreach(lc, root->join_info_list) { SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc); if (sjinfo->jointype == JOIN_ANTI && bms_is_member(forced_null_rel, sjinfo->syn_righthand)) return true; } return false; } /* * distribute_restrictinfo_to_rels * Push a completed RestrictInfo into the proper restriction or join * clause list(s). * * This is the last step of distribute_qual_to_rels() for ordinary qual * clauses. Clauses that are interesting for equivalence-class processing * are diverted to the EC machinery, but may ultimately get fed back here. */ void distribute_restrictinfo_to_rels(PlannerInfo *root, RestrictInfo *restrictinfo) { Relids relids = restrictinfo->required_relids; RelOptInfo *rel; switch (bms_membership(relids)) { case BMS_SINGLETON: /* * There is only one relation participating in the clause, so it * is a restriction clause for that relation. */ rel = find_base_rel(root, bms_singleton_member(relids)); /* Add clause to rel's restriction list */ rel->baserestrictinfo = lappend(rel->baserestrictinfo, restrictinfo); /* Update security level info */ rel->baserestrict_min_security = Min(rel->baserestrict_min_security, restrictinfo->security_level); break; case BMS_MULTIPLE: /* * The clause is a join clause, since there is more than one rel * in its relid set. */ /* * Check for hashjoinable operators. (We don't bother setting the * hashjoin info except in true join clauses.) */ check_hashjoinable(restrictinfo); /* * Likewise, check if the clause is suitable to be used with a * Memoize node to cache inner tuples during a parameterized * nested loop. */ check_memoizable(restrictinfo); /* * Add clause to the join lists of all the relevant relations. */ add_join_clause_to_rels(root, restrictinfo, relids); break; default: /* * clause references no rels, and therefore we have no place to * attach it. Shouldn't get here if callers are working properly. */ elog(ERROR, "cannot cope with variable-free clause"); break; } } /* * process_implied_equality * Create a restrictinfo item that says "item1 op item2", and push it * into the appropriate lists. (In practice opno is always a btree * equality operator.) * * "qualscope" is the nominal syntactic level to impute to the restrictinfo. * This must contain at least all the rels used in the expressions, but it * is used only to set the qual application level when both exprs are * variable-free. Otherwise the qual is applied at the lowest join level * that provides all its variables. * * "nullable_relids" is the set of relids used in the expressions that are * potentially nullable below the expressions. (This has to be supplied by * caller because this function is used after deconstruct_jointree, so we * don't have knowledge of where the clause items came from.) * * "security_level" is the security level to assign to the new restrictinfo. * * "both_const" indicates whether both items are known pseudo-constant; * in this case it is worth applying eval_const_expressions() in case we * can produce constant TRUE or constant FALSE. (Otherwise it's not, * because the expressions went through eval_const_expressions already.) * * Returns the generated RestrictInfo, if any. The result will be NULL * if both_const is true and we successfully reduced the clause to * constant TRUE. * * Note: this function will copy item1 and item2, but it is caller's * responsibility to make sure that the Relids parameters are fresh copies * not shared with other uses. * * Note: we do not do initialize_mergeclause_eclasses() here. It is * caller's responsibility that left_ec/right_ec be set as necessary. */ RestrictInfo * process_implied_equality(PlannerInfo *root, Oid opno, Oid collation, Expr *item1, Expr *item2, Relids qualscope, Relids nullable_relids, Index security_level, bool below_outer_join, bool both_const) { RestrictInfo *restrictinfo; Node *clause; Relids relids; bool pseudoconstant = false; /* * Build the new clause. Copy to ensure it shares no substructure with * original (this is necessary in case there are subselects in there...) */ clause = (Node *) make_opclause(opno, BOOLOID, /* opresulttype */ false, /* opretset */ copyObject(item1), copyObject(item2), InvalidOid, collation); /* If both constant, try to reduce to a boolean constant. */ if (both_const) { clause = eval_const_expressions(root, clause); /* If we produced const TRUE, just drop the clause */ if (clause && IsA(clause, Const)) { Const *cclause = (Const *) clause; Assert(cclause->consttype == BOOLOID); if (!cclause->constisnull && DatumGetBool(cclause->constvalue)) return NULL; } } /* * The rest of this is a very cut-down version of distribute_qual_to_rels. * We can skip most of the work therein, but there are a couple of special * cases we still have to handle. * * Retrieve all relids mentioned within the possibly-simplified clause. */ relids = pull_varnos(root, clause); Assert(bms_is_subset(relids, qualscope)); /* * If the clause is variable-free, our normal heuristic for pushing it * down to just the mentioned rels doesn't work, because there are none. * Apply at the given qualscope, or at the top of tree if it's nonvolatile * (which it very likely is, but we'll check, just to be sure). */ if (bms_is_empty(relids)) { /* eval at original syntactic level */ relids = bms_copy(qualscope); if (!contain_volatile_functions(clause)) { /* mark as gating qual */ pseudoconstant = true; /* tell createplan.c to check for gating quals */ root->hasPseudoConstantQuals = true; /* if not below outer join, push it to top of tree */ if (!below_outer_join) { relids = get_relids_in_jointree((Node *) root->parse->jointree, false); } } } /* * Build the RestrictInfo node itself. */ restrictinfo = make_restrictinfo(root, (Expr *) clause, true, /* is_pushed_down */ false, /* outerjoin_delayed */ pseudoconstant, security_level, relids, NULL, /* outer_relids */ nullable_relids); /* * If it's a join clause, add vars used in the clause to targetlists of * their relations, so that they will be emitted by the plan nodes that * scan those relations (else they won't be available at the join node!). * * Typically, we'd have already done this when the component expressions * were first seen by distribute_qual_to_rels; but it is possible that * some of the Vars could have missed having that done because they only * appeared in single-relation clauses originally. So do it here for * safety. */ if (bms_membership(relids) == BMS_MULTIPLE) { List *vars = pull_var_clause(clause, PVC_RECURSE_AGGREGATES | PVC_RECURSE_WINDOWFUNCS | PVC_INCLUDE_PLACEHOLDERS); add_vars_to_targetlist(root, vars, relids, false); list_free(vars); } /* * Check mergejoinability. This will usually succeed, since the op came * from an EquivalenceClass; but we could have reduced the original clause * to a constant. */ check_mergejoinable(restrictinfo); /* * Note we don't do initialize_mergeclause_eclasses(); the caller can * handle that much more cheaply than we can. It's okay to call * distribute_restrictinfo_to_rels() before that happens. */ /* * Push the new clause into all the appropriate restrictinfo lists. */ distribute_restrictinfo_to_rels(root, restrictinfo); return restrictinfo; } /* * build_implied_join_equality --- build a RestrictInfo for a derived equality * * This overlaps the functionality of process_implied_equality(), but we * must not push the RestrictInfo into the joininfo tree. * * Note: this function will copy item1 and item2, but it is caller's * responsibility to make sure that the Relids parameters are fresh copies * not shared with other uses. * * Note: we do not do initialize_mergeclause_eclasses() here. It is * caller's responsibility that left_ec/right_ec be set as necessary. */ RestrictInfo * build_implied_join_equality(PlannerInfo *root, Oid opno, Oid collation, Expr *item1, Expr *item2, Relids qualscope, Relids nullable_relids, Index security_level) { RestrictInfo *restrictinfo; Expr *clause; /* * Build the new clause. Copy to ensure it shares no substructure with * original (this is necessary in case there are subselects in there...) */ clause = make_opclause(opno, BOOLOID, /* opresulttype */ false, /* opretset */ copyObject(item1), copyObject(item2), InvalidOid, collation); /* * Build the RestrictInfo node itself. */ restrictinfo = make_restrictinfo(root, clause, true, /* is_pushed_down */ false, /* outerjoin_delayed */ false, /* pseudoconstant */ security_level, /* security_level */ qualscope, /* required_relids */ NULL, /* outer_relids */ nullable_relids); /* nullable_relids */ /* Set mergejoinability/hashjoinability flags */ check_mergejoinable(restrictinfo); check_hashjoinable(restrictinfo); check_memoizable(restrictinfo); return restrictinfo; } /* * match_foreign_keys_to_quals * Match foreign-key constraints to equivalence classes and join quals * * The idea here is to see which query join conditions match equality * constraints of a foreign-key relationship. For such join conditions, * we can use the FK semantics to make selectivity estimates that are more * reliable than estimating from statistics, especially for multiple-column * FKs, where the normal assumption of independent conditions tends to fail. * * In this function we annotate the ForeignKeyOptInfos in root->fkey_list * with info about which eclasses and join qual clauses they match, and * discard any ForeignKeyOptInfos that are irrelevant for the query. */ void match_foreign_keys_to_quals(PlannerInfo *root) { List *newlist = NIL; ListCell *lc; foreach(lc, root->fkey_list) { ForeignKeyOptInfo *fkinfo = (ForeignKeyOptInfo *) lfirst(lc); RelOptInfo *con_rel; RelOptInfo *ref_rel; int colno; /* * Either relid might identify a rel that is in the query's rtable but * isn't referenced by the jointree so won't have a RelOptInfo. Hence * don't use find_base_rel() here. We can ignore such FKs. */ if (fkinfo->con_relid >= root->simple_rel_array_size || fkinfo->ref_relid >= root->simple_rel_array_size) continue; /* just paranoia */ con_rel = root->simple_rel_array[fkinfo->con_relid]; if (con_rel == NULL) continue; ref_rel = root->simple_rel_array[fkinfo->ref_relid]; if (ref_rel == NULL) continue; /* * Ignore FK unless both rels are baserels. This gets rid of FKs that * link to inheritance child rels (otherrels) and those that link to * rels removed by join removal (dead rels). */ if (con_rel->reloptkind != RELOPT_BASEREL || ref_rel->reloptkind != RELOPT_BASEREL) continue; /* * Scan the columns and try to match them to eclasses and quals. * * Note: for simple inner joins, any match should be in an eclass. * "Loose" quals that syntactically match an FK equality must have * been rejected for EC status because they are outer-join quals or * similar. We can still consider them to match the FK if they are * not outerjoin_delayed. */ for (colno = 0; colno < fkinfo->nkeys; colno++) { EquivalenceClass *ec; AttrNumber con_attno, ref_attno; Oid fpeqop; ListCell *lc2; ec = match_eclasses_to_foreign_key_col(root, fkinfo, colno); /* Don't bother looking for loose quals if we got an EC match */ if (ec != NULL) { fkinfo->nmatched_ec++; if (ec->ec_has_const) fkinfo->nconst_ec++; continue; } /* * Scan joininfo list for relevant clauses. Either rel's joininfo * list would do equally well; we use con_rel's. */ con_attno = fkinfo->conkey[colno]; ref_attno = fkinfo->confkey[colno]; fpeqop = InvalidOid; /* we'll look this up only if needed */ foreach(lc2, con_rel->joininfo) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc2); OpExpr *clause = (OpExpr *) rinfo->clause; Var *leftvar; Var *rightvar; /* Ignore outerjoin-delayed clauses */ if (rinfo->outerjoin_delayed) continue; /* Only binary OpExprs are useful for consideration */ if (!IsA(clause, OpExpr) || list_length(clause->args) != 2) continue; leftvar = (Var *) get_leftop((Expr *) clause); rightvar = (Var *) get_rightop((Expr *) clause); /* Operands must be Vars, possibly with RelabelType */ while (leftvar && IsA(leftvar, RelabelType)) leftvar = (Var *) ((RelabelType *) leftvar)->arg; if (!(leftvar && IsA(leftvar, Var))) continue; while (rightvar && IsA(rightvar, RelabelType)) rightvar = (Var *) ((RelabelType *) rightvar)->arg; if (!(rightvar && IsA(rightvar, Var))) continue; /* Now try to match the vars to the current foreign key cols */ if (fkinfo->ref_relid == leftvar->varno && ref_attno == leftvar->varattno && fkinfo->con_relid == rightvar->varno && con_attno == rightvar->varattno) { /* Vars match, but is it the right operator? */ if (clause->opno == fkinfo->conpfeqop[colno]) { fkinfo->rinfos[colno] = lappend(fkinfo->rinfos[colno], rinfo); fkinfo->nmatched_ri++; } } else if (fkinfo->ref_relid == rightvar->varno && ref_attno == rightvar->varattno && fkinfo->con_relid == leftvar->varno && con_attno == leftvar->varattno) { /* * Reverse match, must check commutator operator. Look it * up if we didn't already. (In the worst case we might * do multiple lookups here, but that would require an FK * equality operator without commutator, which is * unlikely.) */ if (!OidIsValid(fpeqop)) fpeqop = get_commutator(fkinfo->conpfeqop[colno]); if (clause->opno == fpeqop) { fkinfo->rinfos[colno] = lappend(fkinfo->rinfos[colno], rinfo); fkinfo->nmatched_ri++; } } } /* If we found any matching loose quals, count col as matched */ if (fkinfo->rinfos[colno]) fkinfo->nmatched_rcols++; } /* * Currently, we drop multicolumn FKs that aren't fully matched to the * query. Later we might figure out how to derive some sort of * estimate from them, in which case this test should be weakened to * "if ((fkinfo->nmatched_ec + fkinfo->nmatched_rcols) > 0)". */ if ((fkinfo->nmatched_ec + fkinfo->nmatched_rcols) == fkinfo->nkeys) newlist = lappend(newlist, fkinfo); } /* Replace fkey_list, thereby discarding any useless entries */ root->fkey_list = newlist; } /***************************************************************************** * * CHECKS FOR MERGEJOINABLE AND HASHJOINABLE CLAUSES * *****************************************************************************/ /* * check_mergejoinable * If the restrictinfo's clause is mergejoinable, set the mergejoin * info fields in the restrictinfo. * * Currently, we support mergejoin for binary opclauses where * the operator is a mergejoinable operator. The arguments can be * anything --- as long as there are no volatile functions in them. */ static void check_mergejoinable(RestrictInfo *restrictinfo) { Expr *clause = restrictinfo->clause; Oid opno; Node *leftarg; if (restrictinfo->pseudoconstant) return; if (!is_opclause(clause)) return; if (list_length(((OpExpr *) clause)->args) != 2) return; opno = ((OpExpr *) clause)->opno; leftarg = linitial(((OpExpr *) clause)->args); if (op_mergejoinable(opno, exprType(leftarg)) && !contain_volatile_functions((Node *) restrictinfo)) restrictinfo->mergeopfamilies = get_mergejoin_opfamilies(opno); /* * Note: op_mergejoinable is just a hint; if we fail to find the operator * in any btree opfamilies, mergeopfamilies remains NIL and so the clause * is not treated as mergejoinable. */ } /* * check_hashjoinable * If the restrictinfo's clause is hashjoinable, set the hashjoin * info fields in the restrictinfo. * * Currently, we support hashjoin for binary opclauses where * the operator is a hashjoinable operator. The arguments can be * anything --- as long as there are no volatile functions in them. */ static void check_hashjoinable(RestrictInfo *restrictinfo) { Expr *clause = restrictinfo->clause; Oid opno; Node *leftarg; if (restrictinfo->pseudoconstant) return; if (!is_opclause(clause)) return; if (list_length(((OpExpr *) clause)->args) != 2) return; opno = ((OpExpr *) clause)->opno; leftarg = linitial(((OpExpr *) clause)->args); if (op_hashjoinable(opno, exprType(leftarg)) && !contain_volatile_functions((Node *) restrictinfo)) restrictinfo->hashjoinoperator = opno; } /* * check_memoizable * If the restrictinfo's clause is suitable to be used for a Memoize node, * set the lefthasheqoperator and righthasheqoperator to the hash equality * operator that will be needed during caching. */ static void check_memoizable(RestrictInfo *restrictinfo) { TypeCacheEntry *typentry; Expr *clause = restrictinfo->clause; Oid lefttype; Oid righttype; if (restrictinfo->pseudoconstant) return; if (!is_opclause(clause)) return; if (list_length(((OpExpr *) clause)->args) != 2) return; lefttype = exprType(linitial(((OpExpr *) clause)->args)); typentry = lookup_type_cache(lefttype, TYPECACHE_HASH_PROC | TYPECACHE_EQ_OPR); if (OidIsValid(typentry->hash_proc) && OidIsValid(typentry->eq_opr)) restrictinfo->left_hasheqoperator = typentry->eq_opr; righttype = exprType(lsecond(((OpExpr *) clause)->args)); /* * Lookup the right type, unless it's the same as the left type, in which * case typentry is already pointing to the required TypeCacheEntry. */ if (lefttype != righttype) typentry = lookup_type_cache(righttype, TYPECACHE_HASH_PROC | TYPECACHE_EQ_OPR); if (OidIsValid(typentry->hash_proc) && OidIsValid(typentry->eq_opr)) restrictinfo->right_hasheqoperator = typentry->eq_opr; }