/*------------------------------------------------------------------------- * * prepjointree.c * Planner preprocessing for subqueries and join tree manipulation. * * NOTE: the intended sequence for invoking these operations is * pull_up_sublinks * inline_set_returning_functions * pull_up_subqueries * do expression preprocessing (including flattening JOIN alias vars) * reduce_outer_joins * * * In PostgreSQL, there is code here to do with pulling up "simple UNION ALLs". * In GPDB, there is no such thing as a simple UNION ALL as locus of the relations * may be different, so all that has been removed. * * * Portions Copyright (c) 2006-2008, Greenplum inc * Portions Copyright (c) 2012-Present Pivotal Software, Inc. * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.66.2.2 2010/06/21 00:14:54 tgl Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "catalog/pg_type.h" #include "nodes/makefuncs.h" #include "nodes/nodeFuncs.h" #include "optimizer/clauses.h" #include "optimizer/placeholder.h" #include "optimizer/prep.h" #include "optimizer/subselect.h" #include "optimizer/tlist.h" #include "optimizer/var.h" #include "parser/parse_relation.h" #include "parser/parsetree.h" #include "rewrite/rewriteManip.h" #include "cdb/cdbsubselect.h" #include "optimizer/transform.h" typedef struct pullup_replace_vars_context { PlannerInfo *root; List *targetlist; /* tlist of subquery being pulled up */ RangeTblEntry *target_rte; /* RTE of subquery */ bool *outer_hasSubLinks; /* -> outer query's hasSubLinks */ int varno; /* varno of subquery */ bool need_phvs; /* do we need PlaceHolderVars? */ bool wrap_non_vars; /* do we need 'em on *all* non-Vars? */ Node **rv_cache; /* cache for results with PHVs */ } pullup_replace_vars_context; typedef struct reduce_outer_joins_state { Relids relids; /* base relids within this subtree */ bool contains_outer; /* does subtree contain outer join(s)? */ List *sub_states; /* List of states for subtree components */ } reduce_outer_joins_state; static Node *pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode, Relids *relids); static Node *pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node, Relids available_rels, Node **jtlink); static void pull_up_fromlist_subqueries(PlannerInfo *root, List **inout_fromlist, bool below_outer_join); static Node *pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte, JoinExpr *lowest_outer_join, AppendRelInfo *containing_appendrel); bool is_simple_subquery(PlannerInfo *root, Query *subquery); static bool is_safe_append_member(Query *subquery); static void replace_vars_in_jointree(Node *jtnode, pullup_replace_vars_context *context, JoinExpr *lowest_outer_join); static Node *pullup_replace_vars(Node *expr, pullup_replace_vars_context *context); static Node *pullup_replace_vars_callback(Var *var, replace_rte_variables_context *context); static reduce_outer_joins_state *reduce_outer_joins_pass1(Node *jtnode); static void reduce_outer_joins_pass2(Node *jtnode, reduce_outer_joins_state *state, PlannerInfo *root, Relids nonnullable_rels, List *nonnullable_vars, List *forced_null_vars); static void substitute_multiple_relids(Node *node, int varno, Relids subrelids); static void fix_append_rel_relids(List *append_rel_list, int varno, Relids subrelids); static Node *find_jointree_node_for_rel(Node *jtnode, int relid); static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery, List *colTypes); extern void UpdateScatterClause(Query *query, List *newtlist); /* * pull_up_sublinks * Attempt to pull up ANY and EXISTS SubLinks to be treated as * semijoins or anti-semijoins. * * A clause "foo op ANY (sub-SELECT)" can be processed by pulling the * sub-SELECT up to become a rangetable entry and treating the implied * comparisons as quals of a semijoin. However, this optimization *only* * works at the top level of WHERE or a JOIN/ON clause, because we cannot * distinguish whether the ANY ought to return FALSE or NULL in cases * involving NULL inputs. Also, in an outer join's ON clause we can only * do this if the sublink is degenerate (ie, references only the nullable * side of the join). In that case it is legal to push the semijoin * down into the nullable side of the join. If the sublink references any * nonnullable-side variables then it would have to be evaluated as part * of the outer join, which makes things way too complicated. * * Under similar conditions, EXISTS and NOT EXISTS clauses can be handled * by pulling up the sub-SELECT and creating a semijoin or anti-semijoin. * * This routine searches for such clauses and does the necessary parsetree * transformations if any are found. * * This routine has to run before preprocess_expression(), so the quals * clauses are not yet reduced to implicit-AND format. That means we need * to recursively search through explicit AND clauses, which are * probably only binary ANDs. We stop as soon as we hit a non-AND item. */ void pull_up_sublinks(PlannerInfo *root) { Node *jtnode; Relids relids; /* Begin recursion through the jointree */ jtnode = pull_up_sublinks_jointree_recurse(root, (Node *) root->parse->jointree, &relids); /* * root->parse->jointree must always be a FromExpr, so insert a dummy one * if we got a bare RangeTblRef or JoinExpr out of the recursion. */ if (IsA(jtnode, FromExpr)) root->parse->jointree = (FromExpr *) jtnode; else root->parse->jointree = makeFromExpr(list_make1(jtnode), NULL); } /* * Recurse through jointree nodes for pull_up_sublinks() * * In addition to returning the possibly-modified jointree node, we return * a relids set of the contained rels into *relids. */ static Node * pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode, Relids *relids) { if (jtnode == NULL) { *relids = NULL; } else if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; *relids = bms_make_singleton(varno); /* jtnode is returned unmodified */ } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; List *newfromlist = NIL; Relids frelids = NULL; FromExpr *newf; Node *jtlink; ListCell *l; /* First, recurse to process children and collect their relids */ foreach(l, f->fromlist) { Node *newchild; Relids childrelids; newchild = pull_up_sublinks_jointree_recurse(root, lfirst(l), &childrelids); newfromlist = lappend(newfromlist, newchild); frelids = bms_join(frelids, childrelids); } /* Build the replacement FromExpr; no quals yet */ newf = makeFromExpr(newfromlist, NULL); /* Set up a link representing the rebuilt jointree */ jtlink = (Node *) newf; /* Now process qual --- all children are available for use */ newf->quals = pull_up_sublinks_qual_recurse(root, f->quals, frelids, &jtlink); /* * Note that the result will be either newf, or a stack of JoinExprs * with newf at the base. We rely on subsequent optimization steps * to flatten this and rearrange the joins as needed. * * Although we could include the pulled-up subqueries in the returned * relids, there's no need since upper quals couldn't refer to their * outputs anyway. */ *relids = frelids; jtnode = jtlink;; } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j; Relids leftrelids = NULL; Relids rightrelids = NULL; Node *jtlink; /* * Make a modifiable copy of join node, but don't bother copying * its subnodes (yet). */ j = (JoinExpr *) palloc(sizeof(JoinExpr)); memcpy(j, jtnode, sizeof(JoinExpr)); jtlink = (Node *) j; /* * We support flattening of sublinks in JOIN...ON only for * inner joins */ if (j->jointype == JOIN_INNER) { /* Recurse to process children and collect their relids */ j->larg = pull_up_sublinks_jointree_recurse(root, j->larg, &leftrelids); j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &rightrelids); /* * Now process qual, showing appropriate child relids as available, * and attach any pulled-up jointree items at the right place. * We put new JoinExprs above the existing one (much as for a * FromExpr-style join). The point of the available_rels * machinations is to ensure that we only pull up quals for * which that's okay. */ j->quals = pull_up_sublinks_qual_recurse(root, j->quals, bms_union(leftrelids, rightrelids), &jtlink); } /* * Although we could include the pulled-up subqueries in the returned * relids, there's no need since upper quals couldn't refer to their * outputs anyway. But we *do* need to include the join's own rtindex * because we haven't yet collapsed join alias variables, so upper * levels would mistakenly think they couldn't use references to this * join. */ *relids = bms_join(leftrelids, rightrelids); if (j->rtindex) *relids = bms_add_member(*relids, j->rtindex); jtnode = jtlink; } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return jtnode; } /* * Recurse through top-level qual nodes for pull_up_sublinks() * * jtlink points to the link in the jointree where any new JoinExprs should be * inserted. If we find multiple pull-up-able SubLinks, they'll get stacked * there in the order we encounter them. We rely on subsequent optimization * to rearrange the stack if appropriate. */ static Node * pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node, Relids available_rels, Node **jtlink) { if (node == NULL) return NULL; if (IsA(node, SubLink)) { SubLink *sublink = (SubLink *) node; JoinExpr *j; /* Is it a convertible ANY or EXISTS clause? */ if (sublink->subLinkType == ANY_SUBLINK) { j = convert_ANY_sublink_to_join(root, sublink, available_rels); if (j) { /* Yes, insert the new join node into the join tree */ j->larg = *jtlink; *jtlink = (Node *) j; /* and return NULL representing constant TRUE */ return NULL; } } else if (sublink->subLinkType == EXISTS_SUBLINK) { Node* subst; subst = convert_EXISTS_sublink_to_join(root, sublink, false, available_rels); if (subst && IsA(subst, JoinExpr)) { j = (JoinExpr *) subst; /* Yes, insert the new join node into the join tree */ j->larg = *jtlink; *jtlink = (Node *) j; /* and return NULL representing constant TRUE */ return NULL; } else if(subst) return subst; } else if (sublink->subLinkType == ALL_SUBLINK) { /* GPDB_84_MERGE_FIXME: Should convert_IN_to_antijoin() also use available_rels ? */ j = convert_IN_to_antijoin(root, sublink); if (j) { /* Yes, insert the new join node into the join tree */ j->larg = *jtlink; *jtlink = (Node *) j; /* and return NULL representing constant TRUE */ return NULL; } } /* Else return it unmodified */ return node; } if (not_clause(node)) { /* If the immediate argument of NOT is EXISTS, try to convert */ SubLink *sublink = (SubLink *) get_notclausearg((Expr *) node); Node *arg = (Node *) get_notclausearg((Expr *) node); JoinExpr *j; if (sublink && IsA(sublink, SubLink)) { if (sublink->subLinkType == EXISTS_SUBLINK) { Node* subst; subst = convert_EXISTS_sublink_to_join(root, sublink, true, available_rels); if (subst && IsA(subst, JoinExpr)) { j = (JoinExpr *) subst; /* Yes, insert the new join node into the join tree */ j->larg = *jtlink; *jtlink = (Node *) j; /* and return NULL representing constant TRUE */ return NULL; } else if (subst) return subst; /* Else return it unmodified */ return node; } /* * We normalize NOT subqueries using the following axioms: * * val NOT IN (subq) => val <> ALL (subq) * NOT val op ANY (subq) => val op' ALL (subq) * NOT val op ALL (subq) => val op' ANY (subq) */ else if (sublink->subLinkType == ANY_SUBLINK) { sublink->subLinkType = ALL_SUBLINK; sublink->testexpr = (Node *) canonicalize_qual(make_notclause((Expr *) sublink->testexpr)); } else if (sublink->subLinkType == ALL_SUBLINK) { sublink->subLinkType = ANY_SUBLINK; sublink->testexpr = (Node *) canonicalize_qual(make_notclause((Expr *) sublink->testexpr)); } return pull_up_sublinks_qual_recurse(root, (Node *) sublink, available_rels, jtlink); } else if (not_clause(arg)) { /* NOT NOT (expr) => (expr) */ return (Node *) pull_up_sublinks_qual_recurse(root, (Node *) get_notclausearg((Expr *) arg), available_rels, jtlink); } else if (or_clause(arg)) { /* NOT OR (expr1) (expr2) => (expr1) AND (expr2) */ return (Node *) pull_up_sublinks_qual_recurse(root, (Node *) canonicalize_qual((Expr *) node), available_rels, jtlink); } /* Else return it unmodified */ return node; } if (and_clause(node)) { /* Recurse into AND clause */ List *newclauses = NIL; ListCell *l; foreach(l, ((BoolExpr *) node)->args) { Node *oldclause = (Node *) lfirst(l); Node *newclause; newclause = pull_up_sublinks_qual_recurse(root, oldclause, available_rels, jtlink); if(newclause) newclauses = lappend(newclauses, newclause); } return (Node *) make_ands_explicit(newclauses); } /* * (expr) op SUBLINK */ if (IsA(node, OpExpr)) { OpExpr *opexp = (OpExpr *) node; JoinExpr *j; if (list_length(opexp->args) == 2) { /** * Check if second arg is sublink */ Node *rarg = list_nth(opexp->args, 1); if (IsA(rarg, SubLink)) { /* GPDB_84_MERGE_FIXME: Should convert_EXPR_to_join() also use available_rels ? */ j = convert_EXPR_to_join(root, opexp); if (j) { /* Yes, insert the new join node into the join tree */ j->larg = *jtlink; *jtlink = (Node *) j; } return node; } } } /* Stop if not an AND */ return node; } /* * inline_set_returning_functions * Attempt to "inline" set-returning functions in the FROM clause. * * If an RTE_FUNCTION rtable entry invokes a set-returning function that * contains just a simple SELECT, we can convert the rtable entry to an * RTE_SUBQUERY entry exposing the SELECT directly. This is especially * useful if the subquery can then be "pulled up" for further optimization, * but we do it even if not, to reduce executor overhead. * * This has to be done before we have started to do any optimization of * subqueries, else any such steps wouldn't get applied to subqueries * obtained via inlining. However, we do it after pull_up_IN_clauses * so that we can inline any functions used in IN subselects. * * Like most of the planner, this feels free to scribble on its input data * structure. */ void inline_set_returning_functions(PlannerInfo *root) { ListCell *rt; foreach(rt, root->parse->rtable) { RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt); if (rte->rtekind == RTE_FUNCTION) { Query *funcquery; /* Check safety of expansion, and expand if possible */ funcquery = inline_set_returning_function(root, rte->funcexpr); if (funcquery) { /* * GPDB: Normalize the resulting query, like standard_planner() * does for the main query. */ funcquery = normalize_query(funcquery); /* Successful expansion, replace the rtable entry */ rte->rtekind = RTE_SUBQUERY; rte->subquery = funcquery; rte->funcexpr = NULL; rte->funccoltypes = NIL; rte->funccoltypmods = NIL; } } } } /* * pull_up_subqueries * Look for subqueries in the rangetable that can be pulled up into * the parent query. If the subquery has no special features like * grouping/aggregation then we can merge it into the parent's jointree. * Also, subqueries that are simple UNION ALL structures can be * converted into "append relations". * * below_outer_join is true if this jointree node is within the nullable * side of an outer join. This forces use of the PlaceHolderVar mechanism * for non-nullable targetlist items. * * append_rel_member is true if we are looking at a member subquery of * an append relation. This forces use of the PlaceHolderVar mechanism * for all non-Var targetlist items, and puts some additional restrictions * on what can be pulled up. * * A tricky aspect of this code is that if we pull up a subquery we have * to replace Vars that reference the subquery's outputs throughout the * parent query, including quals attached to jointree nodes above the one * we are currently processing! We handle this by being careful not to * change the jointree structure while recursing: no nodes other than * subquery RangeTblRef entries will be replaced. Also, we can't turn * ResolveNew loose on the whole jointree, because it'll return a mutated * copy of the tree; we have to invoke it just on the quals, instead. */ Node * pull_up_subqueries(PlannerInfo *root, Node *jtnode, JoinExpr *lowest_outer_join, AppendRelInfo *containing_appendrel) { if (jtnode == NULL) return NULL; if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; RangeTblEntry *rte = rt_fetch(varno, root->parse->rtable); /* * Is this a subquery RTE, and if so, is the subquery simple enough to * pull up? * * If we are looking at an append-relation member, we can't pull it up * unless is_safe_append_member says so. */ if (rte->rtekind == RTE_SUBQUERY && !rte->forceDistRandom && is_simple_subquery(root, rte->subquery) && (containing_appendrel == NULL || is_safe_append_member(rte->subquery))) return pull_up_simple_subquery(root, jtnode, rte, lowest_outer_join, containing_appendrel); /* PG: * Alternatively, is it a simple UNION ALL subquery? If so, flatten * into an "append relation". * * It's safe to do this regardless of whether this query is * itself an appendrel member. (If you're thinking we should try to * flatten the two levels of appendrel together, you're right; but we * handle that in set_append_rel_pathlist, not here.) * * GPDB: * Flattening to an append relation works in PG but is not safe to do in GPDB. * A "simple" UNION ALL may involve relations with different loci and would require resolving * locus issues. It is preferable to avoid pulling up simple UNION ALL in GPDB. */ } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; Assert(containing_appendrel == NULL); foreach(l, f->fromlist) lfirst(l) = pull_up_subqueries(root, lfirst(l), lowest_outer_join, NULL); } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; Assert(containing_appendrel == NULL); /* Recurse, being careful to tell myself when inside outer join */ switch (j->jointype) { case JOIN_INNER: case JOIN_SEMI: j->larg = pull_up_subqueries(root, j->larg, lowest_outer_join, NULL); j->rarg = pull_up_subqueries(root, j->rarg, lowest_outer_join, NULL); break; case JOIN_LEFT: case JOIN_ANTI: case JOIN_LASJ_NOTIN: j->larg = pull_up_subqueries(root, j->larg, lowest_outer_join, NULL); j->rarg = pull_up_subqueries(root, j->rarg, j, NULL); break; case JOIN_FULL: j->larg = pull_up_subqueries(root, j->larg, j, NULL); j->rarg = pull_up_subqueries(root, j->rarg, j, NULL); break; case JOIN_RIGHT: j->larg = pull_up_subqueries(root, j->larg, j, NULL); j->rarg = pull_up_subqueries(root, j->rarg, lowest_outer_join, NULL); break; default: elog(ERROR, "unrecognized join type: %d", (int) j->jointype); break; } /* * CDB: If subqueries from the JOIN...ON search condition were * flattened, 'subqfromlist' is a list of RangeTblRef nodes to be * included in the cross product with larg and rarg. Try to pull up * the referenced subqueries. For outer joins, let below_outer_join * be true, because the subquery tables belong in the null-augmented * side of the JOIN (right side of LEFT JOIN). */ ListCell *l; if (j->subqfromlist) foreach(l, j->subqfromlist) { if(lowest_outer_join != NULL) lfirst(l) = pull_up_subqueries(root, lfirst(l), lowest_outer_join, NULL); else if(j->jointype != JOIN_INNER) lfirst(l) = pull_up_subqueries(root, lfirst(l), j, NULL); else lfirst(l) = pull_up_subqueries(root, lfirst(l), NULL, NULL); } } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return jtnode; } /* * GPDB_84_MERGE_FIXME: Check if can be removed * pull_up_fromlist_subqueries * Attempt to pull up subqueries in a List of jointree nodes. */ static void pull_up_fromlist_subqueries(PlannerInfo *root, List **inout_fromlist, bool below_outer_join) { ListCell *l; foreach(l, *inout_fromlist) { Node *oldkid = (Node *)lfirst(l); Node *newkid = pull_up_subqueries(root, oldkid, below_outer_join, false); lfirst(l) = newkid; } } /* pull_up_fromlist_subqueries */ /* * pull_up_simple_subquery * Attempt to pull up a single simple subquery. * * jtnode is a RangeTblRef that has been tentatively identified as a simple * subquery by pull_up_subqueries. We return the replacement jointree node, * or jtnode itself if we determine that the subquery can't be pulled up after * all. * * rte is the RangeTblEntry referenced by jtnode. Remaining parameters are * as for pull_up_subqueries. */ static Node * pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte, JoinExpr *lowest_outer_join, AppendRelInfo *containing_appendrel) { Query *parse = root->parse; int varno = ((RangeTblRef *) jtnode)->rtindex; Query *subquery; PlannerInfo *subroot; int rtoffset; pullup_replace_vars_context rvcontext; ListCell *rt; ListCell *cell; /* * Need a modifiable copy of the subquery to hack on. Even if we didn't * sometimes choose not to pull up below, we must do this to avoid * problems if the same subquery is referenced from multiple jointree * items (which can't happen normally, but might after rule rewriting). */ subquery = copyObject(rte->subquery); /* * Create a PlannerInfo data structure for this subquery. * * NOTE: the next few steps should match the first processing in * subquery_planner(). Can we refactor to avoid code duplication, or * would that just make things uglier? */ subroot = makeNode(PlannerInfo); subroot->parse = subquery; subroot->glob = root->glob; subroot->query_level = root->query_level; subroot->parent_root = root->parent_root; subroot->planner_cxt = CurrentMemoryContext; subroot->init_plans = NIL; subroot->cte_plan_ids = NIL; subroot->eq_classes = NIL; subroot->append_rel_list = NIL; subroot->hasRecursion = false; subroot->wt_param_id = -1; subroot->non_recursive_plan = NULL; /* No CTEs to worry about */ Assert(subquery->cteList == NIL); subroot->list_cteplaninfo = NIL; if (subroot->parse->cteList != NIL) { subroot->list_cteplaninfo = init_list_cteplaninfo(list_length(subroot->parse->cteList)); } /* CDB: Stash subquery jointree relids before flattening subqueries. */ subroot->currlevel_relids = get_relids_in_jointree((Node *)subquery->jointree, false); /* Ensure that jointree has been normalized. See normalize_query_jointree_mutator() */ AssertImply(subquery->jointree->fromlist, list_length(subquery->jointree->fromlist) == 1); subroot->config = CopyPlannerConfig(root->config); subroot->config->honor_order_by = false; /* CDB: Clear fallback */ subroot->config->mpp_trying_fallback_plan = false; /* * Pull up any SubLinks within the subquery's WHERE, so that we don't * leave unoptimized SubLinks behind. */ if (subquery->hasSubLinks) pull_up_sublinks(subroot); /* * Similarly, inline any set-returning functions in its rangetable. */ inline_set_returning_functions(subroot); /* * Recursively pull up the subquery's subqueries, so that * pull_up_subqueries' processing is complete for its jointree and * rangetable. * * Note: we should pass NULL for containing-join info even if we are within an * an outer join in the upper query; the lower query starts with a clean * slate for outer-join semantics. Likewise, we say we aren't handling an * appendrel member. */ subquery->jointree = (FromExpr *) pull_up_subqueries(subroot, (Node *) subquery->jointree, NULL, NULL); /* * Now we must recheck whether the subquery is still simple enough to pull * up. If not, abandon processing it. * * We don't really need to recheck all the conditions involved, but it's * easier just to keep this "if" looking the same as the one in * pull_up_subqueries. */ if (is_simple_subquery(root, subquery) && (containing_appendrel == NULL || is_safe_append_member(subquery))) { /* good to go */ } else { /* * Give up, return unmodified RangeTblRef. * * Note: The work we just did will be redone when the subquery gets * planned on its own. Perhaps we could avoid that by storing the * modified subquery back into the rangetable, but I'm not gonna risk * it now. */ return jtnode; } /* CDB: If parent RTE belongs to subquery's query level, children do too. */ foreach (cell, subroot->append_rel_list) { AppendRelInfo *appinfo = (AppendRelInfo *)lfirst(cell); if (bms_is_member(appinfo->parent_relid, subroot->currlevel_relids)) subroot->currlevel_relids = bms_add_member(subroot->currlevel_relids, appinfo->child_relid); } /* * Adjust level-0 varnos in subquery so that we can append its rangetable * to upper query's. We have to fix the subquery's append_rel_list * as well. */ rtoffset = list_length(parse->rtable); OffsetVarNodes((Node *) subquery, rtoffset, 0); OffsetVarNodes((Node *) subroot->append_rel_list, rtoffset, 0); /* * Upper-level vars in subquery are now one level closer to their parent * than before. */ IncrementVarSublevelsUp((Node *) subquery, -1, 1); IncrementVarSublevelsUp((Node *) subroot->append_rel_list, -1, 1); /* * The subquery's targetlist items are now in the appropriate form to * insert into the top query, but if we are under an outer join then * non-nullable items may have to be turned into PlaceHolderVars. If we * are dealing with an appendrel member then anything that's not a * simple Var has to be turned into a PlaceHolderVar. */ rvcontext.root = root; rvcontext.targetlist = subquery->targetList; rvcontext.target_rte = rte; rvcontext.outer_hasSubLinks = &parse->hasSubLinks; rvcontext.varno = varno; rvcontext.need_phvs = (lowest_outer_join != NULL || containing_appendrel != NULL); rvcontext.wrap_non_vars = (containing_appendrel != NULL); /* initialize cache array with indexes 0 .. length(tlist) */ rvcontext.rv_cache = palloc0((list_length(subquery->targetList) + 1) * sizeof(Node *)); List *newTList = (List *) pullup_replace_vars((Node *) parse->targetList, &rvcontext); if (parse->scatterClause) { UpdateScatterClause(parse, newTList); } /* * Replace all of the top query's references to the subquery's outputs * with copies of the adjusted subtlist items, being careful not to * replace any of the jointree structure. (This'd be a lot cleaner if we * could use query_tree_mutator.) We have to use PHVs in the targetList, * returningList, and havingQual, since those are certainly above any * outer join. replace_vars_in_jointree tracks its location in the jointree * and uses PHVs or not appropriately. */ parse->targetList = newTList; parse->returningList = (List *) pullup_replace_vars((Node *) parse->returningList, &rvcontext); replace_vars_in_jointree((Node *) parse->jointree, &rvcontext, lowest_outer_join); Assert(parse->setOperations == NULL); parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext); if (parse->windowClause) { foreach(cell, parse->windowClause) { WindowClause *wc = (WindowClause *) lfirst(cell); if (wc->startOffset) wc->startOffset = ResolveNew((Node *) wc->startOffset, varno, 0, rte, subquery->targetList, CMD_SELECT, 0, NULL); if (wc->endOffset) wc->endOffset = ResolveNew((Node *) wc->endOffset, varno, 0, rte, subquery->targetList, CMD_SELECT, 0, NULL); } } /* * Replace references in the translated_vars lists of appendrels. * When pulling up an appendrel member, we do not need PHVs in the list * of the parent appendrel --- there isn't any outer join between. * Elsewhere, use PHVs for safety. (This analysis could be made tighter * but it seems unlikely to be worth much trouble.) */ foreach(cell, root->append_rel_list) { AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(cell); bool save_need_phvs = rvcontext.need_phvs; if (appinfo == containing_appendrel) rvcontext.need_phvs = false; appinfo->translated_vars = (List *) pullup_replace_vars((Node *) appinfo->translated_vars, &rvcontext); rvcontext.need_phvs = save_need_phvs; } /* * Replace references in the joinaliasvars lists of join RTEs. * * You might think that we could avoid using PHVs for alias vars of joins * below lowest_outer_join, but that doesn't work because the alias vars * could be referenced above that join; we need the PHVs to be present * in such references after the alias vars get flattened. (It might be * worth trying to be smarter here, someday.) */ foreach(rt, parse->rtable) { RangeTblEntry *otherrte = (RangeTblEntry *) lfirst(rt); if (otherrte->rtekind == RTE_JOIN) otherrte->joinaliasvars = (List *) pullup_replace_vars((Node *) otherrte->joinaliasvars, &rvcontext); else if (otherrte->rtekind == RTE_SUBQUERY && rte != otherrte) { otherrte->subquery = (Query *) ResolveNew((Node *) otherrte->subquery, varno, 1, rte, /* here the sublevels_up can only be 1, because if larger than 1, then the sublink is multilevel correlated, and cannot be pulled up to be a subquery range table; while on the other hand, we cannot directly put a subquery which refer to other relations of the same level after FROM. */ subquery->targetList, CMD_SELECT, 0, NULL); } } /* * Now append the adjusted rtable entries to upper query. (We hold off * until after fixing the upper rtable entries; no point in running that * code on the subquery ones too.) */ parse->rtable = list_concat(parse->rtable, subquery->rtable); /* * Pull up any FOR UPDATE/SHARE markers, too. (OffsetVarNodes already * adjusted the marker rtindexes, so just concat the lists.) */ parse->rowMarks = list_concat(parse->rowMarks, subquery->rowMarks); /* * CDB: Fix current query level's FROM clause relid set if the subquery * was in the FROM clause of current query (not a flattened sublink). */ if (bms_is_member(varno, root->currlevel_relids)) { int subrelid; root->currlevel_relids = bms_del_member(root->currlevel_relids, varno); bms_foreach(subrelid, subroot->currlevel_relids) root->currlevel_relids = bms_add_member(root->currlevel_relids, subrelid + rtoffset); } /* * We also have to fix the relid sets of any append_rel nodes, * PlaceHolderVar nodes in the parent query. (This could perhaps be done * by pullup_replace_vars(), but it seems cleaner to use two passes.) * Note in particular that any placeholder nodes just created by * pullup_replace_vars() will be adjusted. * * Likewise, relids appearing in AppendRelInfo nodes have to be fixed (but * we took care of their translated_vars lists above). We already checked * that this won't require introducing multiple subrelids into the * single-slot AppendRelInfo structs. */ if (parse->hasSubLinks || root->glob->lastPHId != 0 || root->append_rel_list) { Relids subrelids; subrelids = get_relids_in_jointree((Node *) subquery->jointree, false); substitute_multiple_relids((Node *) parse, varno, subrelids); fix_append_rel_relids(root->append_rel_list, varno, subrelids); } /* * And now add subquery's AppendRelInfos to our list. */ root->append_rel_list = list_concat(root->append_rel_list, subroot->append_rel_list); /* * We don't have to do the equivalent bookkeeping for outer-join info, * because that hasn't been set up yet. placeholder_list likewise. */ Assert(root->join_info_list == NIL); Assert(subroot->join_info_list == NIL); Assert(root->placeholder_list == NIL); Assert(subroot->placeholder_list == NIL); /* * Miscellaneous housekeeping. * * * Although replace_rte_variables() faithfully updated parse->hasSubLinks * if it copied any SubLinks out of the subquery's targetlist, we still * could have SubLinks added to the query in the expressions of FUNCTION * and VALUES RTEs copied up from the subquery. So it's necessary to copy * subquery->hasSubLinks anyway. Perhaps this can be improved someday. */ parse->hasSubLinks |= subquery->hasSubLinks; /* subquery won't be pulled up if it hasAggs, so no work there */ /* * CDB: Wipe old RTE so subquery parse tree won't be sent to QEs. */ Assert(rte->rtekind == RTE_SUBQUERY); rte->rtekind = RTE_VOID; rte->subquery = NULL; rte->alias = NULL; rte->eref = NULL; /* * Return the adjusted subquery jointree to replace the RangeTblRef entry * in parent's jointree. */ return (Node *) subquery->jointree; } /* * is_simple_subquery * Check a subquery in the range table to see if it's simple enough * to pull up into the parent query. */ bool is_simple_subquery(PlannerInfo *root, Query *subquery) { /* * Let's just make sure it's a valid subselect ... */ if (!IsA(subquery, Query) || subquery->commandType != CMD_SELECT || subquery->utilityStmt != NULL || subquery->intoClause != NULL) elog(ERROR, "subquery is bogus"); /* * Can't currently pull up a query with setops (unless it's simple UNION * ALL, which is handled by a different code path). Maybe after querytree * redesign... */ if (subquery->setOperations) return false; /* * Can't pull up a subquery involving grouping, aggregation, sorting, * limiting, or WITH. (XXX WITH could possibly be allowed later) */ if (subquery->hasAggs || subquery->hasWindowFuncs || subquery->groupClause || subquery->havingQual || subquery->windowClause || subquery->sortClause || subquery->distinctClause || subquery->limitOffset || subquery->limitCount || subquery->cteList || root->parse->cteList) return false; /* * Don't pull up a subquery that has any set-returning functions in its * targetlist. Otherwise we might well wind up inserting set-returning * functions into places where they mustn't go, such as quals of higher * queries. */ if (expression_returns_set((Node *) subquery->targetList)) return false; /* * Don't pull up a subquery that has any volatile functions in its * targetlist. Otherwise we might introduce multiple evaluations of these * functions, if they get copied to multiple places in the upper query, * leading to surprising results. (Note: the PlaceHolderVar mechanism * doesn't quite guarantee single evaluation; else we could pull up anyway * and just wrap such items in PlaceHolderVars ...) */ if (contain_volatile_functions((Node *) subquery->targetList)) return false; /* * Hack: don't try to pull up a subquery with an empty jointree. * query_planner() will correctly generate a Result plan for a jointree * that's totally empty, but I don't think the right things happen if an * empty FromExpr appears lower down in a jointree. It would pose a * problem for the PlaceHolderVar mechanism too, since we'd have no * way to identify where to evaluate a PHV coming out of the subquery. * Not worth working hard on this, just to collapse SubqueryScan/Result * into Result; especially since the SubqueryScan can often be optimized * away by setrefs.c anyway. */ if (subquery->jointree->fromlist == NIL) return false; return true; } /* * is_simple_union_all * Check a subquery to see if it's a simple UNION ALL. * * We require all the setops to be UNION ALL (no mixing) and there can't be * any datatype coercions involved, ie, all the leaf queries must emit the * same datatypes. */ static bool pg_attribute_unused() is_simple_union_all(Query *subquery) { SetOperationStmt *topop; /* Let's just make sure it's a valid subselect ... */ if (!IsA(subquery, Query) || subquery->commandType != CMD_SELECT || subquery->utilityStmt != NULL || subquery->intoClause != NULL) elog(ERROR, "subquery is bogus"); /* Is it a set-operation query at all? */ topop = (SetOperationStmt *) subquery->setOperations; if (!topop) return false; Assert(IsA(topop, SetOperationStmt)); /* Can't handle ORDER BY, LIMIT/OFFSET, locking, or WITH */ if (subquery->sortClause || subquery->limitOffset || subquery->limitCount || subquery->rowMarks || subquery->cteList) return false; /* Recursively check the tree of set operations */ return is_simple_union_all_recurse((Node *) topop, subquery, topop->colTypes); } static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery, List *colTypes) { if (IsA(setOp, RangeTblRef)) { RangeTblRef *rtr = (RangeTblRef *) setOp; RangeTblEntry *rte = rt_fetch(rtr->rtindex, setOpQuery->rtable); Query *subquery = rte->subquery; Assert(subquery != NULL); /* Leaf nodes are OK if they match the toplevel column types */ /* We don't have to compare typmods here */ return tlist_same_datatypes(subquery->targetList, colTypes, true); } else if (IsA(setOp, SetOperationStmt)) { SetOperationStmt *op = (SetOperationStmt *) setOp; /* Must be UNION ALL */ if (op->op != SETOP_UNION || !op->all) return false; /* Recurse to check inputs */ return is_simple_union_all_recurse(op->larg, setOpQuery, colTypes) && is_simple_union_all_recurse(op->rarg, setOpQuery, colTypes); } else { elog(ERROR, "unrecognized node type: %d", (int) nodeTag(setOp)); return false; /* keep compiler quiet */ } } /* * is_safe_append_member * Check a subquery that is a leaf of a UNION ALL appendrel to see if it's * safe to pull up. */ static bool is_safe_append_member(Query *subquery) { FromExpr *jtnode; /* * It's only safe to pull up the child if its jointree contains exactly * one RTE, else the AppendRelInfo data structure breaks. The one base RTE * could be buried in several levels of FromExpr, however. * * Also, the child can't have any WHERE quals because there's no place to * put them in an appendrel. (This is a bit annoying...) If we didn't * need to check this, we'd just test whether get_relids_in_jointree() * yields a singleton set, to be more consistent with the coding of * fix_append_rel_relids(). */ jtnode = subquery->jointree; while (IsA(jtnode, FromExpr)) { if (jtnode->quals != NULL) return false; if (list_length(jtnode->fromlist) != 1) return false; jtnode = linitial(jtnode->fromlist); } if (!IsA(jtnode, RangeTblRef)) return false; return true; } /* * Helper routine for pull_up_subqueries: do pullup_replace_vars on every expression * in the jointree, without changing the jointree structure itself. Ugly, * but there's no other way... * * If we are above lowest_outer_join then use subtlist_with_phvs; at or * below it, use subtlist. (When no outer joins are in the picture, * these will be the same list.) */ static void replace_vars_in_jointree(Node *jtnode, pullup_replace_vars_context *context, JoinExpr *lowest_outer_join) { ListCell *l; if (jtnode == NULL) return; if (IsA(jtnode, RangeTblRef)) { /* nothing to do here */ } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; foreach(l, f->fromlist) replace_vars_in_jointree(lfirst(l), context, lowest_outer_join); f->quals = pullup_replace_vars(f->quals, context); } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; bool save_need_phvs = context->need_phvs; if (j == lowest_outer_join) { /* no more PHVs in or below this join */ context->need_phvs = false; lowest_outer_join = NULL; } replace_vars_in_jointree(j->larg, context, lowest_outer_join); replace_vars_in_jointree(j->rarg, context, lowest_outer_join); foreach(l, j->subqfromlist) replace_vars_in_jointree(lfirst(l), context, lowest_outer_join); j->quals = pullup_replace_vars(j->quals, context); /* * We don't bother to update the colvars list, since it won't be used * again ... */ context->need_phvs = save_need_phvs; } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); } /* * Apply pullup variable replacement throughout an expression tree * * Returns a modified copy of the tree, so this can't be used where we * need to do in-place replacement. */ static Node * pullup_replace_vars(Node *expr, pullup_replace_vars_context *context) { return replace_rte_variables(expr, context->varno, 0, pullup_replace_vars_callback, (void *) context, context->outer_hasSubLinks); } static Node * pullup_replace_vars_callback(Var *var, replace_rte_variables_context *context) { pullup_replace_vars_context *rcon = (pullup_replace_vars_context *) context->callback_arg; int varattno = var->varattno; Node *newnode; /* * If PlaceHolderVars are needed, we cache the modified expressions in * rcon->rv_cache[]. This is not in hopes of any material speed gain * within this function, but to avoid generating identical PHVs with * different IDs. That would result in duplicate evaluations at runtime, * and possibly prevent optimizations that rely on recognizing different * references to the same subquery output as being equal(). So it's worth * a bit of extra effort to avoid it. */ if (rcon->need_phvs && varattno >= InvalidAttrNumber && varattno <= list_length(rcon->targetlist) && rcon->rv_cache[varattno] != NULL) { /* Just copy the entry and fall through to adjust its varlevelsup */ newnode = copyObject(rcon->rv_cache[varattno]); } else if (varattno == InvalidAttrNumber) { /* Must expand whole-tuple reference into RowExpr */ RowExpr *rowexpr; List *colnames; List *fields; bool save_need_phvs = rcon->need_phvs; int save_sublevelsup = context->sublevels_up; /* * If generating an expansion for a var of a named rowtype (ie, this * is a plain relation RTE), then we must include dummy items for * dropped columns. If the var is RECORD (ie, this is a JOIN), then * omit dropped columns. Either way, attach column names to the * RowExpr for use of ruleutils.c. * * In order to be able to cache the results, we always generate the * expansion with varlevelsup = 0, and then adjust if needed. */ expandRTE(rcon->target_rte, var->varno, 0 /* not varlevelsup */, var->location, (var->vartype != RECORDOID), &colnames, &fields); /* Adjust the generated per-field Vars, but don't insert PHVs */ rcon->need_phvs = false; context->sublevels_up = 0; /* to match the expandRTE output */ fields = (List *) replace_rte_variables_mutator((Node *) fields, context); rcon->need_phvs = save_need_phvs; context->sublevels_up = save_sublevelsup; rowexpr = makeNode(RowExpr); rowexpr->args = fields; rowexpr->row_typeid = var->vartype; rowexpr->row_format = COERCE_IMPLICIT_CAST; rowexpr->colnames = colnames; rowexpr->location = var->location; newnode = (Node *) rowexpr; /* * Insert PlaceHolderVar if needed. Notice that we are wrapping * one PlaceHolderVar around the whole RowExpr, rather than putting * one around each element of the row. This is because we need * the expression to yield NULL, not ROW(NULL,NULL,...) when it * is forced to null by an outer join. */ if (rcon->need_phvs) { /* RowExpr is certainly not strict, so always need PHV */ newnode = (Node *) make_placeholder_expr(rcon->root, (Expr *) newnode, bms_make_singleton(rcon->varno)); /* cache it with the PHV, and with varlevelsup still zero */ rcon->rv_cache[InvalidAttrNumber] = copyObject(newnode); } } else { /* Normal case referencing one targetlist element */ TargetEntry *tle = get_tle_by_resno(rcon->targetlist, varattno); if (tle == NULL) /* shouldn't happen */ elog(ERROR, "could not find attribute %d in subquery targetlist", varattno); /* Make a copy of the tlist item to return */ newnode = copyObject(tle->expr); /* Insert PlaceHolderVar if needed */ if (rcon->need_phvs) { bool wrap; if (newnode && IsA(newnode, Var) && ((Var *) newnode)->varlevelsup == 0) { /* Simple Vars always escape being wrapped */ wrap = false; } else if (rcon->wrap_non_vars) { /* Wrap all non-Vars in a PlaceHolderVar */ wrap = true; } else { /* * If it contains a Var of current level, and does not contain * any non-strict constructs, then it's certainly nullable and * we don't need to insert a PlaceHolderVar. (Note: in future * maybe we should insert PlaceHolderVars anyway, when a tlist * item is expensive to evaluate? */ if (contain_vars_of_level((Node *) newnode, 0) && !contain_nonstrict_functions((Node *) newnode)) { /* No wrap needed */ wrap = false; } else { /* Else wrap it in a PlaceHolderVar */ wrap = true; } } if (wrap) newnode = (Node *) make_placeholder_expr(rcon->root, (Expr *) newnode, bms_make_singleton(rcon->varno)); /* * Cache it if possible (ie, if the attno is in range, which it * probably always should be). We can cache the value even if * we decided we didn't need a PHV, since this result will be * suitable for any request that has need_phvs. */ if (varattno > InvalidAttrNumber && varattno <= list_length(rcon->targetlist)) rcon->rv_cache[varattno] = copyObject(newnode); } } /* Must adjust varlevelsup if tlist item is from higher query */ if (var->varlevelsup > 0) IncrementVarSublevelsUp(newnode, var->varlevelsup, 0); return newnode; } /* * reduce_outer_joins * Attempt to reduce outer joins to plain inner joins. * * The idea here is that given a query like * SELECT ... FROM a LEFT JOIN b ON (...) WHERE b.y = 42; * we can reduce the LEFT JOIN to a plain JOIN if the "=" operator in WHERE * is strict. The strict operator will always return NULL, causing the outer * WHERE to fail, on any row where the LEFT JOIN filled in NULLs for b's * columns. Therefore, there's no need for the join to produce null-extended * rows in the first place --- which makes it a plain join not an outer join. * (This scenario may not be very likely in a query written out by hand, but * it's reasonably likely when pushing quals down into complex views.) * * More generally, an outer join can be reduced in strength if there is a * strict qual above it in the qual tree that constrains a Var from the * nullable side of the join to be non-null. (For FULL joins this applies * to each side separately.) * * Another transformation we apply here is to recognize cases like * SELECT ... FROM a LEFT JOIN b ON (a.x = b.y) WHERE b.y IS NULL; * If the join clause is strict for b.y, then only null-extended rows could * pass the upper WHERE, and we can conclude that what the query is really * specifying is an anti-semijoin. We change the join type from JOIN_LEFT * to JOIN_ANTI. The IS NULL clause then becomes redundant, and must be * removed to prevent bogus selectivity calculations, but we leave it to * distribute_qual_to_rels to get rid of such clauses. * * Also, we get rid of JOIN_RIGHT cases by flipping them around to become * JOIN_LEFT. This saves some code here and in some later planner routines, * but the main reason to do it is to not need to invent a JOIN_REVERSE_ANTI * join type. * * To ease recognition of strict qual clauses, we require this routine to be * run after expression preprocessing (i.e., qual canonicalization and JOIN * alias-var expansion). */ void reduce_outer_joins(PlannerInfo *root) { reduce_outer_joins_state *state; /* * To avoid doing strictness checks on more quals than necessary, we want * to stop descending the jointree as soon as there are no outer joins * below our current point. This consideration forces a two-pass process. * The first pass gathers information about which base rels appear below * each side of each join clause, and about whether there are outer * join(s) below each side of each join clause. The second pass examines * qual clauses and changes join types as it descends the tree. */ state = reduce_outer_joins_pass1((Node *) root->parse->jointree); /* planner.c shouldn't have called me if no outer joins */ if (state == NULL || !state->contains_outer) elog(ERROR, "so where are the outer joins?"); reduce_outer_joins_pass2((Node *) root->parse->jointree, state, root, NULL, NIL, NIL); } /* * reduce_outer_joins_pass1 - phase 1 data collection * * Returns a state node describing the given jointree node. */ static reduce_outer_joins_state * reduce_outer_joins_pass1(Node *jtnode) { reduce_outer_joins_state *result; ListCell *l; result = (reduce_outer_joins_state *) palloc(sizeof(reduce_outer_joins_state)); result->relids = NULL; result->contains_outer = false; result->sub_states = NIL; if (jtnode == NULL) return result; if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; result->relids = bms_make_singleton(varno); } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; foreach(l, f->fromlist) { reduce_outer_joins_state *sub_state; sub_state = reduce_outer_joins_pass1(lfirst(l)); result->relids = bms_add_members(result->relids, sub_state->relids); result->contains_outer |= sub_state->contains_outer; result->sub_states = lappend(result->sub_states, sub_state); } } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; reduce_outer_joins_state *sub_state; /* join's own RT index is not wanted in result->relids */ if (IS_OUTER_JOIN(j->jointype)) result->contains_outer = true; sub_state = reduce_outer_joins_pass1(j->larg); result->relids = bms_add_members(result->relids, sub_state->relids); result->contains_outer |= sub_state->contains_outer; result->sub_states = lappend(result->sub_states, sub_state); sub_state = reduce_outer_joins_pass1(j->rarg); result->relids = bms_add_members(result->relids, sub_state->relids); result->contains_outer |= sub_state->contains_outer; result->sub_states = lappend(result->sub_states, sub_state); foreach(l, j->subqfromlist) { sub_state = reduce_outer_joins_pass1(lfirst(l)); result->relids = bms_add_members(result->relids, sub_state->relids); result->contains_outer |= sub_state->contains_outer; result->sub_states = lappend(result->sub_states, sub_state); } } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return result; } /* * reduce_outer_joins_pass2 - phase 2 processing * * jtnode: current jointree node * state: state data collected by phase 1 for this node * root: toplevel planner state * nonnullable_rels: set of base relids forced non-null by upper quals * nonnullable_vars: list of Vars forced non-null by upper quals * forced_null_vars: list of Vars forced null by upper quals */ static void reduce_outer_joins_pass2(Node *jtnode, reduce_outer_joins_state *state, PlannerInfo *root, Relids nonnullable_rels, List *nonnullable_vars, List *forced_null_vars) { ListCell *l; ListCell *s; /* * pass 2 should never descend as far as an empty subnode or base rel, * because it's only called on subtrees marked as contains_outer. */ if (jtnode == NULL) elog(ERROR, "reached empty jointree"); if (IsA(jtnode, RangeTblRef)) elog(ERROR, "reached base rel"); else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; ListCell *s; Relids pass_nonnullable_rels; List *pass_nonnullable_vars; List *pass_forced_null_vars; /* Scan quals to see if we can add any constraints */ pass_nonnullable_rels = find_nonnullable_rels(f->quals); pass_nonnullable_rels = bms_add_members(pass_nonnullable_rels, nonnullable_rels); /* NB: we rely on list_concat to not damage its second argument */ pass_nonnullable_vars = find_nonnullable_vars(f->quals); pass_nonnullable_vars = list_concat(pass_nonnullable_vars, nonnullable_vars); pass_forced_null_vars = find_forced_null_vars(f->quals); pass_forced_null_vars = list_concat(pass_forced_null_vars, forced_null_vars); /* And recurse --- but only into interesting subtrees */ Assert(list_length(f->fromlist) == list_length(state->sub_states)); forboth(l, f->fromlist, s, state->sub_states) { reduce_outer_joins_state *sub_state = lfirst(s); if (sub_state->contains_outer) reduce_outer_joins_pass2(lfirst(l), sub_state, root, pass_nonnullable_rels, pass_nonnullable_vars, pass_forced_null_vars); } bms_free(pass_nonnullable_rels); /* can't so easily clean up var lists, unfortunately */ } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; int rtindex = j->rtindex; JoinType jointype = j->jointype; reduce_outer_joins_state *left_state = linitial(state->sub_states); reduce_outer_joins_state *right_state = lsecond(state->sub_states); reduce_outer_joins_state *sub_state; List *local_nonnullable_vars = NIL; bool computed_local_nonnullable_vars = false; /* Can we simplify this join? */ switch (jointype) { case JOIN_INNER: break; case JOIN_LEFT: if (bms_overlap(nonnullable_rels, right_state->relids)) jointype = JOIN_INNER; break; case JOIN_RIGHT: if (bms_overlap(nonnullable_rels, left_state->relids)) jointype = JOIN_INNER; break; case JOIN_FULL: if (bms_overlap(nonnullable_rels, left_state->relids)) { if (bms_overlap(nonnullable_rels, right_state->relids)) jointype = JOIN_INNER; else jointype = JOIN_LEFT; } else { if (bms_overlap(nonnullable_rels, right_state->relids)) jointype = JOIN_RIGHT; } break; case JOIN_LASJ_NOTIN: case JOIN_SEMI: case JOIN_ANTI: /* * These could only have been introduced by pull_up_sublinks, * so there's no way that upper quals could refer to their * righthand sides, and no point in checking. */ break; default: elog(ERROR, "unrecognized join type: %d", (int) jointype); break; } /* * Convert JOIN_RIGHT to JOIN_LEFT. Note that in the case where we * reduced JOIN_FULL to JOIN_RIGHT, this will mean the JoinExpr no * longer matches the internal ordering of any CoalesceExpr's built to * represent merged join variables. We don't care about that at * present, but be wary of it ... */ if (jointype == JOIN_RIGHT) { Node *tmparg; tmparg = j->larg; j->larg = j->rarg; j->rarg = tmparg; jointype = JOIN_LEFT; right_state = linitial(state->sub_states); left_state = lsecond(state->sub_states); } /* * See if we can reduce JOIN_LEFT to JOIN_ANTI. This is the case * if the join's own quals are strict for any var that was forced * null by higher qual levels. NOTE: there are other ways that we * could detect an anti-join, in particular if we were to check * whether Vars coming from the RHS must be non-null because of * table constraints. That seems complicated and expensive though * (in particular, one would have to be wary of lower outer joins). * For the moment this seems sufficient. */ if (jointype == JOIN_LEFT) { List *overlap; local_nonnullable_vars = find_nonnullable_vars(j->quals); computed_local_nonnullable_vars = true; /* * It's not sufficient to check whether local_nonnullable_vars * and forced_null_vars overlap: we need to know if the overlap * includes any RHS variables. */ overlap = list_intersection(local_nonnullable_vars, forced_null_vars); if (overlap != NIL && bms_overlap(pull_varnos((Node *) overlap), right_state->relids)) jointype = JOIN_ANTI; } /* Apply the jointype change, if any, to both jointree node and RTE */ if (rtindex && jointype != j->jointype) { RangeTblEntry *rte = rt_fetch(rtindex, root->parse->rtable); Assert(rte->rtekind == RTE_JOIN); Assert(rte->jointype == j->jointype); rte->jointype = jointype; } j->jointype = jointype; if (left_state->contains_outer || right_state->contains_outer) { Relids local_nonnullable_rels; List *local_forced_null_vars; Relids pass_nonnullable_rels; List *pass_nonnullable_vars; List *pass_forced_null_vars; /* * If this join is (now) inner, we can add any constraints its * quals provide to those we got from above. But if it is outer, * we can pass down the local constraints only into the nullable * side, because an outer join never eliminates any rows from its * non-nullable side. Also, there is no point in passing upper * constraints into the nullable side, since if there were any * we'd have been able to reduce the join. (In the case of * upper forced-null constraints, we *must not* pass them into * the nullable side --- they either applied here, or not.) * The upshot is that we pass either the local or the upper * constraints, never both, to the children of an outer join. * * At a FULL join we just punt and pass nothing down --- is it * possible to be smarter? */ if (jointype != JOIN_FULL) { local_nonnullable_rels = find_nonnullable_rels(j->quals); if (!computed_local_nonnullable_vars) local_nonnullable_vars = find_nonnullable_vars(j->quals); local_forced_null_vars = find_forced_null_vars(j->quals); if (jointype == JOIN_INNER) { /* OK to merge upper and local constraints */ local_nonnullable_rels = bms_add_members(local_nonnullable_rels, nonnullable_rels); local_nonnullable_vars = list_concat(local_nonnullable_vars, nonnullable_vars); local_forced_null_vars = list_concat(local_forced_null_vars, forced_null_vars); } } else { /* no use in calculating these */ local_nonnullable_rels = NULL; local_forced_null_vars = NIL; } if (left_state->contains_outer) { if (jointype == JOIN_INNER || jointype == JOIN_SEMI) { /* pass union of local and upper constraints */ pass_nonnullable_rels = local_nonnullable_rels; pass_nonnullable_vars = local_nonnullable_vars; pass_forced_null_vars = local_forced_null_vars; } else if (jointype != JOIN_FULL) /* ie, LEFT/SEMI/ANTI */ { /* can't pass local constraints to non-nullable side */ pass_nonnullable_rels = nonnullable_rels; pass_nonnullable_vars = nonnullable_vars; pass_forced_null_vars = forced_null_vars; } else { /* no constraints pass through JOIN_FULL */ pass_nonnullable_rels = NULL; pass_nonnullable_vars = NIL; pass_forced_null_vars = NIL; } reduce_outer_joins_pass2(j->larg, left_state, root, pass_nonnullable_rels, pass_nonnullable_vars, pass_forced_null_vars); } if (right_state->contains_outer) { if (jointype != JOIN_FULL) /* ie, INNER/LEFT/SEMI/ANTI */ { /* pass appropriate constraints, per comment above */ pass_nonnullable_rels = local_nonnullable_rels; pass_nonnullable_vars = local_nonnullable_vars; pass_forced_null_vars = local_forced_null_vars; } else { /* no constraints pass through JOIN_FULL */ pass_nonnullable_rels = NULL; pass_nonnullable_vars = NIL; pass_forced_null_vars = NIL; } reduce_outer_joins_pass2(j->rarg, right_state, root, pass_nonnullable_rels, pass_nonnullable_vars, pass_forced_null_vars); } /* * CDB: Simplify outer joins pulled up from flattened subqueries. * For a left or right outer join, the subqfromlist items belong * to the null-augmented side; so we pass local_nonnullable down * regardless of the jointype. (For FULL JOIN, subqfromlist is * always empty.) */ s = lnext(lnext(list_head(state->sub_states))); foreach(l, j->subqfromlist) { sub_state = (reduce_outer_joins_state *)lfirst(s); if (sub_state->contains_outer) reduce_outer_joins_pass2(lfirst(l), sub_state, root, pass_nonnullable_rels, pass_nonnullable_vars, pass_forced_null_vars); s = lnext(s); } bms_free(local_nonnullable_rels); } } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); } /* * substitute_multiple_relids - adjust node relid sets after pulling up * a subquery * * Find any PlaceHolderVar nodes in the given tree that * reference the pulled-up relid, and change them to reference the replacement * relid(s). We do not need to recurse into subqueries, since no subquery of * the current top query could (yet) contain such a reference. * * NOTE: although this has the form of a walker, we cheat and modify the * nodes in-place. This should be OK since the tree was copied by pullup_replace_vars * earlier. Avoid scribbling on the original values of the bitmapsets, though, * because expression_tree_mutator doesn't copy those. */ typedef struct { int varno; Relids subrelids; } substitute_multiple_relids_context; static bool substitute_multiple_relids_walker(Node *node, substitute_multiple_relids_context *context) { if (node == NULL) return false; if (IsA(node, PlaceHolderVar)) { PlaceHolderVar *phv = (PlaceHolderVar *) node; if (bms_is_member(context->varno, phv->phrels)) { phv->phrels = bms_union(phv->phrels, context->subrelids); phv->phrels = bms_del_member(phv->phrels, context->varno); } /* fall through to examine children */ } /* Shouldn't need to handle planner auxiliary nodes here */ Assert(!IsA(node, SpecialJoinInfo)); Assert(!IsA(node, AppendRelInfo)); Assert(!IsA(node, PlaceHolderInfo)); return expression_tree_walker(node, substitute_multiple_relids_walker, (void *) context); } static void substitute_multiple_relids(Node *node, int varno, Relids subrelids) { substitute_multiple_relids_context context; context.varno = varno; context.subrelids = subrelids; /* * Must be prepared to start with a Query or a bare expression tree. */ query_or_expression_tree_walker(node, substitute_multiple_relids_walker, (void *) &context, 0); } /* * fix_append_rel_relids: update RT-index fields of AppendRelInfo nodes * * When we pull up a subquery, any AppendRelInfo references to the subquery's * RT index have to be replaced by the substituted relid (and there had better * be only one). * * We assume we may modify the AppendRelInfo nodes in-place. */ static void fix_append_rel_relids(List *append_rel_list, int varno, Relids subrelids) { ListCell *l; int subvarno = -1; /* * We only want to extract the member relid once, but we mustn't fail * immediately if there are multiple members; it could be that none of the * AppendRelInfo nodes refer to it. So compute it on first use. Note that * bms_singleton_member will complain if set is not singleton. */ foreach(l, append_rel_list) { AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l); /* The parent_relid shouldn't ever be a pullup target */ Assert(appinfo->parent_relid != varno); if (appinfo->child_relid == varno) { if (subvarno < 0) subvarno = bms_singleton_member(subrelids); appinfo->child_relid = subvarno; } } } /* * get_relids_in_jointree: get set of RT indexes present in a jointree * * If include_joins is true, join RT indexes are included; if false, * only base rels are included. */ Relids get_relids_in_jointree(Node *jtnode, bool include_joins) { Relids result = NULL; ListCell *l; if (jtnode == NULL) return result; if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; result = bms_make_singleton(varno); } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; foreach(l, f->fromlist) { result = bms_join(result, get_relids_in_jointree(lfirst(l), include_joins)); } } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; result = get_relids_in_jointree(j->larg, include_joins); result = bms_join(result, get_relids_in_jointree(j->rarg, include_joins)); if (include_joins && j->rtindex) result = bms_add_member(result, j->rtindex); /* GPDB_84_MERGE_FIXME: Not present upstream; is this really needed? */ foreach(l, j->subqfromlist) result = bms_join(result, get_relids_in_jointree((Node *)lfirst(l), include_joins)); } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return result; } /* * get_relids_for_join: get set of base RT indexes making up a join */ Relids get_relids_for_join(PlannerInfo *root, int joinrelid) { Node *jtnode; jtnode = find_jointree_node_for_rel((Node *) root->parse->jointree, joinrelid); if (!jtnode) elog(ERROR, "could not find join node %d", joinrelid); return get_relids_in_jointree(jtnode, false); } /* * find_jointree_node_for_rel: locate jointree node for a base or join RT index * * Returns NULL if not found */ static Node * find_jointree_node_for_rel(Node *jtnode, int relid) { ListCell *l; if (jtnode == NULL) return NULL; if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; if (relid == varno) return jtnode; } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; foreach(l, f->fromlist) { jtnode = find_jointree_node_for_rel(lfirst(l), relid); if (jtnode) return jtnode; } } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; if (relid == j->rtindex) return jtnode; jtnode = find_jointree_node_for_rel(j->larg, relid); if (jtnode) return jtnode; jtnode = find_jointree_node_for_rel(j->rarg, relid); if (jtnode) return jtnode; foreach(l, j->subqfromlist) { jtnode = find_jointree_node_for_rel(lfirst(l), relid); if (jtnode) return jtnode; } } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return NULL; } /* * init_list_cteplaninfo * Create a list of CtePlanInfos of size 'numCtes', and initialize each CtePlanInfo. */ List * init_list_cteplaninfo(int numCtes) { List *list_cteplaninfo = NULL; for (int cteNo = 0; cteNo < numCtes; cteNo++) { CtePlanInfo *ctePlanInfo = palloc0(sizeof(CtePlanInfo)); list_cteplaninfo = lappend(list_cteplaninfo, ctePlanInfo); } return list_cteplaninfo; }