/*------------------------------------------------------------------------- * * relnode.c * Relation-node lookup/construction routines * * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * src/backend/optimizer/util/relnode.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include #include "miscadmin.h" #include "optimizer/clauses.h" #include "optimizer/cost.h" #include "optimizer/pathnode.h" #include "optimizer/paths.h" #include "optimizer/placeholder.h" #include "optimizer/plancat.h" #include "optimizer/restrictinfo.h" #include "optimizer/tlist.h" #include "utils/hsearch.h" typedef struct JoinHashEntry { Relids join_relids; /* hash key --- MUST BE FIRST */ RelOptInfo *join_rel; } JoinHashEntry; static void build_joinrel_tlist(PlannerInfo *root, RelOptInfo *joinrel, RelOptInfo *input_rel); static List *build_joinrel_restrictlist(PlannerInfo *root, RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel); static void build_joinrel_joinlist(RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel); static List *subbuild_joinrel_restrictlist(RelOptInfo *joinrel, List *joininfo_list, List *new_restrictlist); static List *subbuild_joinrel_joinlist(RelOptInfo *joinrel, List *joininfo_list, List *new_joininfo); static void set_foreign_rel_properties(RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel); static void add_join_rel(PlannerInfo *root, RelOptInfo *joinrel); /* * setup_simple_rel_arrays * Prepare the arrays we use for quickly accessing base relations. */ void setup_simple_rel_arrays(PlannerInfo *root) { Index rti; ListCell *lc; /* Arrays are accessed using RT indexes (1..N) */ root->simple_rel_array_size = list_length(root->parse->rtable) + 1; /* simple_rel_array is initialized to all NULLs */ root->simple_rel_array = (RelOptInfo **) palloc0(root->simple_rel_array_size * sizeof(RelOptInfo *)); /* simple_rte_array is an array equivalent of the rtable list */ root->simple_rte_array = (RangeTblEntry **) palloc0(root->simple_rel_array_size * sizeof(RangeTblEntry *)); rti = 1; foreach(lc, root->parse->rtable) { RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc); root->simple_rte_array[rti++] = rte; } } /* * build_simple_rel * Construct a new RelOptInfo for a base relation or 'other' relation. */ RelOptInfo * build_simple_rel(PlannerInfo *root, int relid, RelOptInfo *parent) { RelOptInfo *rel; RangeTblEntry *rte; /* Rel should not exist already */ Assert(relid > 0 && relid < root->simple_rel_array_size); if (root->simple_rel_array[relid] != NULL) elog(ERROR, "rel %d already exists", relid); /* Fetch RTE for relation */ rte = root->simple_rte_array[relid]; Assert(rte != NULL); rel = makeNode(RelOptInfo); rel->reloptkind = parent ? RELOPT_OTHER_MEMBER_REL : RELOPT_BASEREL; rel->relids = bms_make_singleton(relid); rel->rows = 0; /* cheap startup cost is interesting iff not all tuples to be retrieved */ rel->consider_startup = (root->tuple_fraction > 0); rel->consider_param_startup = false; /* might get changed later */ rel->consider_parallel = false; /* might get changed later */ rel->reltarget = create_empty_pathtarget(); rel->pathlist = NIL; rel->ppilist = NIL; rel->partial_pathlist = NIL; rel->cheapest_startup_path = NULL; rel->cheapest_total_path = NULL; rel->cheapest_unique_path = NULL; rel->cheapest_parameterized_paths = NIL; rel->direct_lateral_relids = NULL; rel->lateral_relids = NULL; rel->relid = relid; rel->rtekind = rte->rtekind; /* min_attr, max_attr, attr_needed, attr_widths are set below */ rel->lateral_vars = NIL; rel->lateral_referencers = NULL; rel->indexlist = NIL; rel->statlist = NIL; rel->pages = 0; rel->tuples = 0; rel->allvisfrac = 0; rel->subroot = NULL; rel->subplan_params = NIL; rel->rel_parallel_workers = -1; /* set up in get_relation_info */ rel->serverid = InvalidOid; rel->userid = rte->checkAsUser; rel->useridiscurrent = false; rel->fdwroutine = NULL; rel->fdw_private = NULL; rel->unique_for_rels = NIL; rel->non_unique_for_rels = NIL; rel->baserestrictinfo = NIL; rel->baserestrictcost.startup = 0; rel->baserestrictcost.per_tuple = 0; rel->baserestrict_min_security = UINT_MAX; rel->joininfo = NIL; rel->has_eclass_joins = false; /* * Pass top parent's relids down the inheritance hierarchy. If the parent * has top_parent_relids set, it's a direct or an indirect child of the * top parent indicated by top_parent_relids. By extension this child is * also an indirect child of that parent. */ if (parent) { if (parent->top_parent_relids) rel->top_parent_relids = parent->top_parent_relids; else rel->top_parent_relids = bms_copy(parent->relids); } else rel->top_parent_relids = NULL; /* Check type of rtable entry */ switch (rte->rtekind) { case RTE_RELATION: /* Table --- retrieve statistics from the system catalogs */ get_relation_info(root, rte->relid, rte->inh, rel); break; case RTE_SUBQUERY: case RTE_FUNCTION: case RTE_TABLEFUNC: case RTE_VALUES: case RTE_CTE: case RTE_NAMEDTUPLESTORE: /* * Subquery, function, tablefunc, values list, CTE, or ENR --- set * up attr range and arrays * * Note: 0 is included in range to support whole-row Vars */ rel->min_attr = 0; rel->max_attr = list_length(rte->eref->colnames); rel->attr_needed = (Relids *) palloc0((rel->max_attr - rel->min_attr + 1) * sizeof(Relids)); rel->attr_widths = (int32 *) palloc0((rel->max_attr - rel->min_attr + 1) * sizeof(int32)); break; default: elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind); break; } /* Save the finished struct in the query's simple_rel_array */ root->simple_rel_array[relid] = rel; /* * This is a convenient spot at which to note whether rels participating * in the query have any securityQuals attached. If so, increase * root->qual_security_level to ensure it's larger than the maximum * security level needed for securityQuals. */ if (rte->securityQuals) root->qual_security_level = Max(root->qual_security_level, list_length(rte->securityQuals)); /* * If this rel is an appendrel parent, recurse to build "other rel" * RelOptInfos for its children. They are "other rels" because they are * not in the main join tree, but we will need RelOptInfos to plan access * to them. */ if (rte->inh) { ListCell *l; foreach(l, root->append_rel_list) { AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l); /* append_rel_list contains all append rels; ignore others */ if (appinfo->parent_relid != relid) continue; (void) build_simple_rel(root, appinfo->child_relid, rel); } } return rel; } /* * find_base_rel * Find a base or other relation entry, which must already exist. */ RelOptInfo * find_base_rel(PlannerInfo *root, int relid) { RelOptInfo *rel; Assert(relid > 0); if (relid < root->simple_rel_array_size) { rel = root->simple_rel_array[relid]; if (rel) return rel; } elog(ERROR, "no relation entry for relid %d", relid); return NULL; /* keep compiler quiet */ } /* * build_join_rel_hash * Construct the auxiliary hash table for join relations. */ static void build_join_rel_hash(PlannerInfo *root) { HTAB *hashtab; HASHCTL hash_ctl; ListCell *l; /* Create the hash table */ MemSet(&hash_ctl, 0, sizeof(hash_ctl)); hash_ctl.keysize = sizeof(Relids); hash_ctl.entrysize = sizeof(JoinHashEntry); hash_ctl.hash = bitmap_hash; hash_ctl.match = bitmap_match; hash_ctl.hcxt = CurrentMemoryContext; hashtab = hash_create("JoinRelHashTable", 256L, &hash_ctl, HASH_ELEM | HASH_FUNCTION | HASH_COMPARE | HASH_CONTEXT); /* Insert all the already-existing joinrels */ foreach(l, root->join_rel_list) { RelOptInfo *rel = (RelOptInfo *) lfirst(l); JoinHashEntry *hentry; bool found; hentry = (JoinHashEntry *) hash_search(hashtab, &(rel->relids), HASH_ENTER, &found); Assert(!found); hentry->join_rel = rel; } root->join_rel_hash = hashtab; } /* * find_join_rel * Returns relation entry corresponding to 'relids' (a set of RT indexes), * or NULL if none exists. This is for join relations. */ RelOptInfo * find_join_rel(PlannerInfo *root, Relids relids) { /* * Switch to using hash lookup when list grows "too long". The threshold * is arbitrary and is known only here. */ if (!root->join_rel_hash && list_length(root->join_rel_list) > 32) build_join_rel_hash(root); /* * Use either hashtable lookup or linear search, as appropriate. * * Note: the seemingly redundant hashkey variable is used to avoid taking * the address of relids; unless the compiler is exceedingly smart, doing * so would force relids out of a register and thus probably slow down the * list-search case. */ if (root->join_rel_hash) { Relids hashkey = relids; JoinHashEntry *hentry; hentry = (JoinHashEntry *) hash_search(root->join_rel_hash, &hashkey, HASH_FIND, NULL); if (hentry) return hentry->join_rel; } else { ListCell *l; foreach(l, root->join_rel_list) { RelOptInfo *rel = (RelOptInfo *) lfirst(l); if (bms_equal(rel->relids, relids)) return rel; } } return NULL; } /* * set_foreign_rel_properties * Set up foreign-join fields if outer and inner relation are foreign * tables (or joins) belonging to the same server and assigned to the same * user to check access permissions as. * * In addition to an exact match of userid, we allow the case where one side * has zero userid (implying current user) and the other side has explicit * userid that happens to equal the current user; but in that case, pushdown of * the join is only valid for the current user. The useridiscurrent field * records whether we had to make such an assumption for this join or any * sub-join. * * Otherwise these fields are left invalid, so GetForeignJoinPaths will not be * called for the join relation. * */ static void set_foreign_rel_properties(RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel) { if (OidIsValid(outer_rel->serverid) && inner_rel->serverid == outer_rel->serverid) { if (inner_rel->userid == outer_rel->userid) { joinrel->serverid = outer_rel->serverid; joinrel->userid = outer_rel->userid; joinrel->useridiscurrent = outer_rel->useridiscurrent || inner_rel->useridiscurrent; joinrel->fdwroutine = outer_rel->fdwroutine; } else if (!OidIsValid(inner_rel->userid) && outer_rel->userid == GetUserId()) { joinrel->serverid = outer_rel->serverid; joinrel->userid = outer_rel->userid; joinrel->useridiscurrent = true; joinrel->fdwroutine = outer_rel->fdwroutine; } else if (!OidIsValid(outer_rel->userid) && inner_rel->userid == GetUserId()) { joinrel->serverid = outer_rel->serverid; joinrel->userid = inner_rel->userid; joinrel->useridiscurrent = true; joinrel->fdwroutine = outer_rel->fdwroutine; } } } /* * add_join_rel * Add given join relation to the list of join relations in the given * PlannerInfo. Also add it to the auxiliary hashtable if there is one. */ static void add_join_rel(PlannerInfo *root, RelOptInfo *joinrel) { /* GEQO requires us to append the new joinrel to the end of the list! */ root->join_rel_list = lappend(root->join_rel_list, joinrel); /* store it into the auxiliary hashtable if there is one. */ if (root->join_rel_hash) { JoinHashEntry *hentry; bool found; hentry = (JoinHashEntry *) hash_search(root->join_rel_hash, &(joinrel->relids), HASH_ENTER, &found); Assert(!found); hentry->join_rel = joinrel; } } /* * build_join_rel * Returns relation entry corresponding to the union of two given rels, * creating a new relation entry if none already exists. * * 'joinrelids' is the Relids set that uniquely identifies the join * 'outer_rel' and 'inner_rel' are relation nodes for the relations to be * joined * 'sjinfo': join context info * 'restrictlist_ptr': result variable. If not NULL, *restrictlist_ptr * receives the list of RestrictInfo nodes that apply to this * particular pair of joinable relations. * * restrictlist_ptr makes the routine's API a little grotty, but it saves * duplicated calculation of the restrictlist... */ RelOptInfo * build_join_rel(PlannerInfo *root, Relids joinrelids, RelOptInfo *outer_rel, RelOptInfo *inner_rel, SpecialJoinInfo *sjinfo, List **restrictlist_ptr) { RelOptInfo *joinrel; List *restrictlist; /* * See if we already have a joinrel for this set of base rels. */ joinrel = find_join_rel(root, joinrelids); if (joinrel) { /* * Yes, so we only need to figure the restrictlist for this particular * pair of component relations. */ if (restrictlist_ptr) *restrictlist_ptr = build_joinrel_restrictlist(root, joinrel, outer_rel, inner_rel); return joinrel; } /* * Nope, so make one. */ joinrel = makeNode(RelOptInfo); joinrel->reloptkind = RELOPT_JOINREL; joinrel->relids = bms_copy(joinrelids); joinrel->rows = 0; /* cheap startup cost is interesting iff not all tuples to be retrieved */ joinrel->consider_startup = (root->tuple_fraction > 0); joinrel->consider_param_startup = false; joinrel->consider_parallel = false; joinrel->reltarget = create_empty_pathtarget(); joinrel->pathlist = NIL; joinrel->ppilist = NIL; joinrel->partial_pathlist = NIL; joinrel->cheapest_startup_path = NULL; joinrel->cheapest_total_path = NULL; joinrel->cheapest_unique_path = NULL; joinrel->cheapest_parameterized_paths = NIL; /* init direct_lateral_relids from children; we'll finish it up below */ joinrel->direct_lateral_relids = bms_union(outer_rel->direct_lateral_relids, inner_rel->direct_lateral_relids); joinrel->lateral_relids = min_join_parameterization(root, joinrel->relids, outer_rel, inner_rel); joinrel->relid = 0; /* indicates not a baserel */ joinrel->rtekind = RTE_JOIN; joinrel->min_attr = 0; joinrel->max_attr = 0; joinrel->attr_needed = NULL; joinrel->attr_widths = NULL; joinrel->lateral_vars = NIL; joinrel->lateral_referencers = NULL; joinrel->indexlist = NIL; joinrel->statlist = NIL; joinrel->pages = 0; joinrel->tuples = 0; joinrel->allvisfrac = 0; joinrel->subroot = NULL; joinrel->subplan_params = NIL; joinrel->rel_parallel_workers = -1; joinrel->serverid = InvalidOid; joinrel->userid = InvalidOid; joinrel->useridiscurrent = false; joinrel->fdwroutine = NULL; joinrel->fdw_private = NULL; joinrel->unique_for_rels = NIL; joinrel->non_unique_for_rels = NIL; joinrel->baserestrictinfo = NIL; joinrel->baserestrictcost.startup = 0; joinrel->baserestrictcost.per_tuple = 0; joinrel->baserestrict_min_security = UINT_MAX; joinrel->joininfo = NIL; joinrel->has_eclass_joins = false; joinrel->top_parent_relids = NULL; /* Compute information relevant to the foreign relations. */ set_foreign_rel_properties(joinrel, outer_rel, inner_rel); /* * Create a new tlist containing just the vars that need to be output from * this join (ie, are needed for higher joinclauses or final output). * * NOTE: the tlist order for a join rel will depend on which pair of outer * and inner rels we first try to build it from. But the contents should * be the same regardless. */ build_joinrel_tlist(root, joinrel, outer_rel); build_joinrel_tlist(root, joinrel, inner_rel); add_placeholders_to_joinrel(root, joinrel, outer_rel, inner_rel); /* * add_placeholders_to_joinrel also took care of adding the ph_lateral * sets of any PlaceHolderVars computed here to direct_lateral_relids, so * now we can finish computing that. This is much like the computation of * the transitively-closed lateral_relids in min_join_parameterization, * except that here we *do* have to consider the added PHVs. */ joinrel->direct_lateral_relids = bms_del_members(joinrel->direct_lateral_relids, joinrel->relids); if (bms_is_empty(joinrel->direct_lateral_relids)) joinrel->direct_lateral_relids = NULL; /* * Construct restrict and join clause lists for the new joinrel. (The * caller might or might not need the restrictlist, but I need it anyway * for set_joinrel_size_estimates().) */ restrictlist = build_joinrel_restrictlist(root, joinrel, outer_rel, inner_rel); if (restrictlist_ptr) *restrictlist_ptr = restrictlist; build_joinrel_joinlist(joinrel, outer_rel, inner_rel); /* * This is also the right place to check whether the joinrel has any * pending EquivalenceClass joins. */ joinrel->has_eclass_joins = has_relevant_eclass_joinclause(root, joinrel); /* * Set estimates of the joinrel's size. */ set_joinrel_size_estimates(root, joinrel, outer_rel, inner_rel, sjinfo, restrictlist); /* * Set the consider_parallel flag if this joinrel could potentially be * scanned within a parallel worker. If this flag is false for either * inner_rel or outer_rel, then it must be false for the joinrel also. * Even if both are true, there might be parallel-restricted expressions * in the targetlist or quals. * * Note that if there are more than two rels in this relation, they could * be divided between inner_rel and outer_rel in any arbitrary way. We * assume this doesn't matter, because we should hit all the same baserels * and joinclauses while building up to this joinrel no matter which we * take; therefore, we should make the same decision here however we get * here. */ if (inner_rel->consider_parallel && outer_rel->consider_parallel && is_parallel_safe(root, (Node *) restrictlist) && is_parallel_safe(root, (Node *) joinrel->reltarget->exprs)) joinrel->consider_parallel = true; /* Add the joinrel to the PlannerInfo. */ add_join_rel(root, joinrel); /* * Also, if dynamic-programming join search is active, add the new joinrel * to the appropriate sublist. Note: you might think the Assert on number * of members should be for equality, but some of the level 1 rels might * have been joinrels already, so we can only assert <=. */ if (root->join_rel_level) { Assert(root->join_cur_level > 0); Assert(root->join_cur_level <= bms_num_members(joinrel->relids)); root->join_rel_level[root->join_cur_level] = lappend(root->join_rel_level[root->join_cur_level], joinrel); } return joinrel; } /* * min_join_parameterization * * Determine the minimum possible parameterization of a joinrel, that is, the * set of other rels it contains LATERAL references to. We save this value in * the join's RelOptInfo. This function is split out of build_join_rel() * because join_is_legal() needs the value to check a prospective join. */ Relids min_join_parameterization(PlannerInfo *root, Relids joinrelids, RelOptInfo *outer_rel, RelOptInfo *inner_rel) { Relids result; /* * Basically we just need the union of the inputs' lateral_relids, less * whatever is already in the join. * * It's not immediately obvious that this is a valid way to compute the * result, because it might seem that we're ignoring possible lateral refs * of PlaceHolderVars that are due to be computed at the join but not in * either input. However, because create_lateral_join_info() already * charged all such PHV refs to each member baserel of the join, they'll * be accounted for already in the inputs' lateral_relids. Likewise, we * do not need to worry about doing transitive closure here, because that * was already accounted for in the original baserel lateral_relids. */ result = bms_union(outer_rel->lateral_relids, inner_rel->lateral_relids); result = bms_del_members(result, joinrelids); /* Maintain invariant that result is exactly NULL if empty */ if (bms_is_empty(result)) result = NULL; return result; } /* * build_joinrel_tlist * Builds a join relation's target list from an input relation. * (This is invoked twice to handle the two input relations.) * * The join's targetlist includes all Vars of its member relations that * will still be needed above the join. This subroutine adds all such * Vars from the specified input rel's tlist to the join rel's tlist. * * We also compute the expected width of the join's output, making use * of data that was cached at the baserel level by set_rel_width(). */ static void build_joinrel_tlist(PlannerInfo *root, RelOptInfo *joinrel, RelOptInfo *input_rel) { Relids relids = joinrel->relids; ListCell *vars; foreach(vars, input_rel->reltarget->exprs) { Var *var = (Var *) lfirst(vars); RelOptInfo *baserel; int ndx; /* * Ignore PlaceHolderVars in the input tlists; we'll make our own * decisions about whether to copy them. */ if (IsA(var, PlaceHolderVar)) continue; /* * Otherwise, anything in a baserel or joinrel targetlist ought to be * a Var. (More general cases can only appear in appendrel child * rels, which will never be seen here.) */ if (!IsA(var, Var)) elog(ERROR, "unexpected node type in rel targetlist: %d", (int) nodeTag(var)); /* Get the Var's original base rel */ baserel = find_base_rel(root, var->varno); /* Is it still needed above this joinrel? */ ndx = var->varattno - baserel->min_attr; if (bms_nonempty_difference(baserel->attr_needed[ndx], relids)) { /* Yup, add it to the output */ joinrel->reltarget->exprs = lappend(joinrel->reltarget->exprs, var); /* Vars have cost zero, so no need to adjust reltarget->cost */ joinrel->reltarget->width += baserel->attr_widths[ndx]; } } } /* * build_joinrel_restrictlist * build_joinrel_joinlist * These routines build lists of restriction and join clauses for a * join relation from the joininfo lists of the relations it joins. * * These routines are separate because the restriction list must be * built afresh for each pair of input sub-relations we consider, whereas * the join list need only be computed once for any join RelOptInfo. * The join list is fully determined by the set of rels making up the * joinrel, so we should get the same results (up to ordering) from any * candidate pair of sub-relations. But the restriction list is whatever * is not handled in the sub-relations, so it depends on which * sub-relations are considered. * * If a join clause from an input relation refers to base rels still not * present in the joinrel, then it is still a join clause for the joinrel; * we put it into the joininfo list for the joinrel. Otherwise, * the clause is now a restrict clause for the joined relation, and we * return it to the caller of build_joinrel_restrictlist() to be stored in * join paths made from this pair of sub-relations. (It will not need to * be considered further up the join tree.) * * In many case we will find the same RestrictInfos in both input * relations' joinlists, so be careful to eliminate duplicates. * Pointer equality should be a sufficient test for dups, since all * the various joinlist entries ultimately refer to RestrictInfos * pushed into them by distribute_restrictinfo_to_rels(). * * 'joinrel' is a join relation node * 'outer_rel' and 'inner_rel' are a pair of relations that can be joined * to form joinrel. * * build_joinrel_restrictlist() returns a list of relevant restrictinfos, * whereas build_joinrel_joinlist() stores its results in the joinrel's * joininfo list. One or the other must accept each given clause! * * NB: Formerly, we made deep(!) copies of each input RestrictInfo to pass * up to the join relation. I believe this is no longer necessary, because * RestrictInfo nodes are no longer context-dependent. Instead, just include * the original nodes in the lists made for the join relation. */ static List * build_joinrel_restrictlist(PlannerInfo *root, RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel) { List *result; /* * Collect all the clauses that syntactically belong at this level, * eliminating any duplicates (important since we will see many of the * same clauses arriving from both input relations). */ result = subbuild_joinrel_restrictlist(joinrel, outer_rel->joininfo, NIL); result = subbuild_joinrel_restrictlist(joinrel, inner_rel->joininfo, result); /* * Add on any clauses derived from EquivalenceClasses. These cannot be * redundant with the clauses in the joininfo lists, so don't bother * checking. */ result = list_concat(result, generate_join_implied_equalities(root, joinrel->relids, outer_rel->relids, inner_rel)); return result; } static void build_joinrel_joinlist(RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel) { List *result; /* * Collect all the clauses that syntactically belong above this level, * eliminating any duplicates (important since we will see many of the * same clauses arriving from both input relations). */ result = subbuild_joinrel_joinlist(joinrel, outer_rel->joininfo, NIL); result = subbuild_joinrel_joinlist(joinrel, inner_rel->joininfo, result); joinrel->joininfo = result; } static List * subbuild_joinrel_restrictlist(RelOptInfo *joinrel, List *joininfo_list, List *new_restrictlist) { ListCell *l; foreach(l, joininfo_list) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(l); if (bms_is_subset(rinfo->required_relids, joinrel->relids)) { /* * This clause becomes a restriction clause for the joinrel, since * it refers to no outside rels. Add it to the list, being * careful to eliminate duplicates. (Since RestrictInfo nodes in * different joinlists will have been multiply-linked rather than * copied, pointer equality should be a sufficient test.) */ new_restrictlist = list_append_unique_ptr(new_restrictlist, rinfo); } else { /* * This clause is still a join clause at this level, so we ignore * it in this routine. */ } } return new_restrictlist; } static List * subbuild_joinrel_joinlist(RelOptInfo *joinrel, List *joininfo_list, List *new_joininfo) { ListCell *l; foreach(l, joininfo_list) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(l); if (bms_is_subset(rinfo->required_relids, joinrel->relids)) { /* * This clause becomes a restriction clause for the joinrel, since * it refers to no outside rels. So we can ignore it in this * routine. */ } else { /* * This clause is still a join clause at this level, so add it to * the new joininfo list, being careful to eliminate duplicates. * (Since RestrictInfo nodes in different joinlists will have been * multiply-linked rather than copied, pointer equality should be * a sufficient test.) */ new_joininfo = list_append_unique_ptr(new_joininfo, rinfo); } } return new_joininfo; } /* * build_empty_join_rel * Build a dummy join relation describing an empty set of base rels. * * This is used for queries with empty FROM clauses, such as "SELECT 2+2" or * "INSERT INTO foo VALUES(...)". We don't try very hard to make the empty * joinrel completely valid, since no real planning will be done with it --- * we just need it to carry a simple Result path out of query_planner(). */ RelOptInfo * build_empty_join_rel(PlannerInfo *root) { RelOptInfo *joinrel; /* The dummy join relation should be the only one ... */ Assert(root->join_rel_list == NIL); joinrel = makeNode(RelOptInfo); joinrel->reloptkind = RELOPT_JOINREL; joinrel->relids = NULL; /* empty set */ joinrel->rows = 1; /* we produce one row for such cases */ joinrel->rtekind = RTE_JOIN; joinrel->reltarget = create_empty_pathtarget(); root->join_rel_list = lappend(root->join_rel_list, joinrel); return joinrel; } /* * fetch_upper_rel * Build a RelOptInfo describing some post-scan/join query processing, * or return a pre-existing one if somebody already built it. * * An "upper" relation is identified by an UpperRelationKind and a Relids set. * The meaning of the Relids set is not specified here, and very likely will * vary for different relation kinds. * * Most of the fields in an upper-level RelOptInfo are not used and are not * set here (though makeNode should ensure they're zeroes). We basically only * care about fields that are of interest to add_path() and set_cheapest(). */ RelOptInfo * fetch_upper_rel(PlannerInfo *root, UpperRelationKind kind, Relids relids) { RelOptInfo *upperrel; ListCell *lc; /* * For the moment, our indexing data structure is just a List for each * relation kind. If we ever get so many of one kind that this stops * working well, we can improve it. No code outside this function should * assume anything about how to find a particular upperrel. */ /* If we already made this upperrel for the query, return it */ foreach(lc, root->upper_rels[kind]) { upperrel = (RelOptInfo *) lfirst(lc); if (bms_equal(upperrel->relids, relids)) return upperrel; } upperrel = makeNode(RelOptInfo); upperrel->reloptkind = RELOPT_UPPER_REL; upperrel->relids = bms_copy(relids); /* cheap startup cost is interesting iff not all tuples to be retrieved */ upperrel->consider_startup = (root->tuple_fraction > 0); upperrel->consider_param_startup = false; upperrel->consider_parallel = false; /* might get changed later */ upperrel->reltarget = create_empty_pathtarget(); upperrel->pathlist = NIL; upperrel->cheapest_startup_path = NULL; upperrel->cheapest_total_path = NULL; upperrel->cheapest_unique_path = NULL; upperrel->cheapest_parameterized_paths = NIL; root->upper_rels[kind] = lappend(root->upper_rels[kind], upperrel); return upperrel; } /* * find_childrel_appendrelinfo * Get the AppendRelInfo associated with an appendrel child rel. * * This search could be eliminated by storing a link in child RelOptInfos, * but for now it doesn't seem performance-critical. (Also, it might be * difficult to maintain such a link during mutation of the append_rel_list.) */ AppendRelInfo * find_childrel_appendrelinfo(PlannerInfo *root, RelOptInfo *rel) { Index relid = rel->relid; ListCell *lc; /* Should only be called on child rels */ Assert(rel->reloptkind == RELOPT_OTHER_MEMBER_REL); foreach(lc, root->append_rel_list) { AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(lc); if (appinfo->child_relid == relid) return appinfo; } /* should have found the entry ... */ elog(ERROR, "child rel %d not found in append_rel_list", relid); return NULL; /* not reached */ } /* * find_childrel_parents * Compute the set of parent relids of an appendrel child rel. * * Since appendrels can be nested, a child could have multiple levels of * appendrel ancestors. This function computes a Relids set of all the * parent relation IDs. */ Relids find_childrel_parents(PlannerInfo *root, RelOptInfo *rel) { Relids result = NULL; Assert(rel->reloptkind == RELOPT_OTHER_MEMBER_REL); do { AppendRelInfo *appinfo = find_childrel_appendrelinfo(root, rel); Index prelid = appinfo->parent_relid; result = bms_add_member(result, prelid); /* traverse up to the parent rel, loop if it's also a child rel */ rel = find_base_rel(root, prelid); } while (rel->reloptkind == RELOPT_OTHER_MEMBER_REL); Assert(rel->reloptkind == RELOPT_BASEREL); return result; } /* * get_baserel_parampathinfo * Get the ParamPathInfo for a parameterized path for a base relation, * constructing one if we don't have one already. * * This centralizes estimating the rowcounts for parameterized paths. * We need to cache those to be sure we use the same rowcount for all paths * of the same parameterization for a given rel. This is also a convenient * place to determine which movable join clauses the parameterized path will * be responsible for evaluating. */ ParamPathInfo * get_baserel_parampathinfo(PlannerInfo *root, RelOptInfo *baserel, Relids required_outer) { ParamPathInfo *ppi; Relids joinrelids; List *pclauses; double rows; ListCell *lc; /* Unparameterized paths have no ParamPathInfo */ if (bms_is_empty(required_outer)) return NULL; Assert(!bms_overlap(baserel->relids, required_outer)); /* If we already have a PPI for this parameterization, just return it */ if ((ppi = find_param_path_info(baserel, required_outer))) return ppi; /* * Identify all joinclauses that are movable to this base rel given this * parameterization. */ joinrelids = bms_union(baserel->relids, required_outer); pclauses = NIL; foreach(lc, baserel->joininfo) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); if (join_clause_is_movable_into(rinfo, baserel->relids, joinrelids)) pclauses = lappend(pclauses, rinfo); } /* * Add in joinclauses generated by EquivalenceClasses, too. (These * necessarily satisfy join_clause_is_movable_into.) */ pclauses = list_concat(pclauses, generate_join_implied_equalities(root, joinrelids, required_outer, baserel)); /* Estimate the number of rows returned by the parameterized scan */ rows = get_parameterized_baserel_size(root, baserel, pclauses); /* And now we can build the ParamPathInfo */ ppi = makeNode(ParamPathInfo); ppi->ppi_req_outer = required_outer; ppi->ppi_rows = rows; ppi->ppi_clauses = pclauses; baserel->ppilist = lappend(baserel->ppilist, ppi); return ppi; } /* * get_joinrel_parampathinfo * Get the ParamPathInfo for a parameterized path for a join relation, * constructing one if we don't have one already. * * This centralizes estimating the rowcounts for parameterized paths. * We need to cache those to be sure we use the same rowcount for all paths * of the same parameterization for a given rel. This is also a convenient * place to determine which movable join clauses the parameterized path will * be responsible for evaluating. * * outer_path and inner_path are a pair of input paths that can be used to * construct the join, and restrict_clauses is the list of regular join * clauses (including clauses derived from EquivalenceClasses) that must be * applied at the join node when using these inputs. * * Unlike the situation for base rels, the set of movable join clauses to be * enforced at a join varies with the selected pair of input paths, so we * must calculate that and pass it back, even if we already have a matching * ParamPathInfo. We handle this by adding any clauses moved down to this * join to *restrict_clauses, which is an in/out parameter. (The addition * is done in such a way as to not modify the passed-in List structure.) * * Note: when considering a nestloop join, the caller must have removed from * restrict_clauses any movable clauses that are themselves scheduled to be * pushed into the right-hand path. We do not do that here since it's * unnecessary for other join types. */ ParamPathInfo * get_joinrel_parampathinfo(PlannerInfo *root, RelOptInfo *joinrel, Path *outer_path, Path *inner_path, SpecialJoinInfo *sjinfo, Relids required_outer, List **restrict_clauses) { ParamPathInfo *ppi; Relids join_and_req; Relids outer_and_req; Relids inner_and_req; List *pclauses; List *eclauses; List *dropped_ecs; double rows; ListCell *lc; /* Unparameterized paths have no ParamPathInfo or extra join clauses */ if (bms_is_empty(required_outer)) return NULL; Assert(!bms_overlap(joinrel->relids, required_outer)); /* * Identify all joinclauses that are movable to this join rel given this * parameterization. These are the clauses that are movable into this * join, but not movable into either input path. Treat an unparameterized * input path as not accepting parameterized clauses (because it won't, * per the shortcut exit above), even though the joinclause movement rules * might allow the same clauses to be moved into a parameterized path for * that rel. */ join_and_req = bms_union(joinrel->relids, required_outer); if (outer_path->param_info) outer_and_req = bms_union(outer_path->parent->relids, PATH_REQ_OUTER(outer_path)); else outer_and_req = NULL; /* outer path does not accept parameters */ if (inner_path->param_info) inner_and_req = bms_union(inner_path->parent->relids, PATH_REQ_OUTER(inner_path)); else inner_and_req = NULL; /* inner path does not accept parameters */ pclauses = NIL; foreach(lc, joinrel->joininfo) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); if (join_clause_is_movable_into(rinfo, joinrel->relids, join_and_req) && !join_clause_is_movable_into(rinfo, outer_path->parent->relids, outer_and_req) && !join_clause_is_movable_into(rinfo, inner_path->parent->relids, inner_and_req)) pclauses = lappend(pclauses, rinfo); } /* Consider joinclauses generated by EquivalenceClasses, too */ eclauses = generate_join_implied_equalities(root, join_and_req, required_outer, joinrel); /* We only want ones that aren't movable to lower levels */ dropped_ecs = NIL; foreach(lc, eclauses) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); /* * In principle, join_clause_is_movable_into() should accept anything * returned by generate_join_implied_equalities(); but because its * analysis is only approximate, sometimes it doesn't. So we * currently cannot use this Assert; instead just assume it's okay to * apply the joinclause at this level. */ #ifdef NOT_USED Assert(join_clause_is_movable_into(rinfo, joinrel->relids, join_and_req)); #endif if (join_clause_is_movable_into(rinfo, outer_path->parent->relids, outer_and_req)) continue; /* drop if movable into LHS */ if (join_clause_is_movable_into(rinfo, inner_path->parent->relids, inner_and_req)) { /* drop if movable into RHS, but remember EC for use below */ Assert(rinfo->left_ec == rinfo->right_ec); dropped_ecs = lappend(dropped_ecs, rinfo->left_ec); continue; } pclauses = lappend(pclauses, rinfo); } /* * EquivalenceClasses are harder to deal with than we could wish, because * of the fact that a given EC can generate different clauses depending on * context. Suppose we have an EC {X.X, Y.Y, Z.Z} where X and Y are the * LHS and RHS of the current join and Z is in required_outer, and further * suppose that the inner_path is parameterized by both X and Z. The code * above will have produced either Z.Z = X.X or Z.Z = Y.Y from that EC, * and in the latter case will have discarded it as being movable into the * RHS. However, the EC machinery might have produced either Y.Y = X.X or * Y.Y = Z.Z as the EC enforcement clause within the inner_path; it will * not have produced both, and we can't readily tell from here which one * it did pick. If we add no clause to this join, we'll end up with * insufficient enforcement of the EC; either Z.Z or X.X will fail to be * constrained to be equal to the other members of the EC. (When we come * to join Z to this X/Y path, we will certainly drop whichever EC clause * is generated at that join, so this omission won't get fixed later.) * * To handle this, for each EC we discarded such a clause from, try to * generate a clause connecting the required_outer rels to the join's LHS * ("Z.Z = X.X" in the terms of the above example). If successful, and if * the clause can't be moved to the LHS, add it to the current join's * restriction clauses. (If an EC cannot generate such a clause then it * has nothing that needs to be enforced here, while if the clause can be * moved into the LHS then it should have been enforced within that path.) * * Note that we don't need similar processing for ECs whose clause was * considered to be movable into the LHS, because the LHS can't refer to * the RHS so there is no comparable ambiguity about what it might * actually be enforcing internally. */ if (dropped_ecs) { Relids real_outer_and_req; real_outer_and_req = bms_union(outer_path->parent->relids, required_outer); eclauses = generate_join_implied_equalities_for_ecs(root, dropped_ecs, real_outer_and_req, required_outer, outer_path->parent); foreach(lc, eclauses) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); /* As above, can't quite assert this here */ #ifdef NOT_USED Assert(join_clause_is_movable_into(rinfo, outer_path->parent->relids, real_outer_and_req)); #endif if (!join_clause_is_movable_into(rinfo, outer_path->parent->relids, outer_and_req)) pclauses = lappend(pclauses, rinfo); } } /* * Now, attach the identified moved-down clauses to the caller's * restrict_clauses list. By using list_concat in this order, we leave * the original list structure of restrict_clauses undamaged. */ *restrict_clauses = list_concat(pclauses, *restrict_clauses); /* If we already have a PPI for this parameterization, just return it */ if ((ppi = find_param_path_info(joinrel, required_outer))) return ppi; /* Estimate the number of rows returned by the parameterized join */ rows = get_parameterized_joinrel_size(root, joinrel, outer_path, inner_path, sjinfo, *restrict_clauses); /* * And now we can build the ParamPathInfo. No point in saving the * input-pair-dependent clause list, though. * * Note: in GEQO mode, we'll be called in a temporary memory context, but * the joinrel structure is there too, so no problem. */ ppi = makeNode(ParamPathInfo); ppi->ppi_req_outer = required_outer; ppi->ppi_rows = rows; ppi->ppi_clauses = NIL; joinrel->ppilist = lappend(joinrel->ppilist, ppi); return ppi; } /* * get_appendrel_parampathinfo * Get the ParamPathInfo for a parameterized path for an append relation. * * For an append relation, the rowcount estimate will just be the sum of * the estimates for its children. However, we still need a ParamPathInfo * to flag the fact that the path requires parameters. So this just creates * a suitable struct with zero ppi_rows (and no ppi_clauses either, since * the Append node isn't responsible for checking quals). */ ParamPathInfo * get_appendrel_parampathinfo(RelOptInfo *appendrel, Relids required_outer) { ParamPathInfo *ppi; /* Unparameterized paths have no ParamPathInfo */ if (bms_is_empty(required_outer)) return NULL; Assert(!bms_overlap(appendrel->relids, required_outer)); /* If we already have a PPI for this parameterization, just return it */ if ((ppi = find_param_path_info(appendrel, required_outer))) return ppi; /* Else build the ParamPathInfo */ ppi = makeNode(ParamPathInfo); ppi->ppi_req_outer = required_outer; ppi->ppi_rows = 0; ppi->ppi_clauses = NIL; appendrel->ppilist = lappend(appendrel->ppilist, ppi); return ppi; } /* * Returns a ParamPathInfo for the parameterization given by required_outer, if * already available in the given rel. Returns NULL otherwise. */ ParamPathInfo * find_param_path_info(RelOptInfo *rel, Relids required_outer) { ListCell *lc; foreach(lc, rel->ppilist) { ParamPathInfo *ppi = (ParamPathInfo *) lfirst(lc); if (bms_equal(ppi->ppi_req_outer, required_outer)) return ppi; } return NULL; }