/* ------------------------------------------------------------------------- * * prepjointree.cpp * Planner preprocessing for subqueries and join tree manipulation. * * NOTE: the intended sequence for invoking these operations is * replace_empty_jointree * pull_up_sublinks * inline_set_returning_functions * pull_up_subqueries * flatten_simple_union_all * do expression preprocessing (including flattening JOIN alias vars) * reduce_outer_joins * remove_useless_result_rtes * * * Portions Copyright (c) 2020 Huawei Technologies Co.,Ltd. * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 2021, openGauss Contributors * * * IDENTIFICATION * src/gausskernel/optimizer/prep/prepjointree.cpp * * ------------------------------------------------------------------------- */ #include "postgres.h" #include "knl/knl_variable.h" #include "catalog/pg_type.h" #include "nodes/makefuncs.h" #include "nodes/nodeFuncs.h" #include "parser/parse_hint.h" #include "optimizer/clauses.h" #include "optimizer/nodegroups.h" #include "optimizer/placeholder.h" #include "optimizer/prep.h" #include "optimizer/subselect.h" #include "optimizer/tlist.h" #include "parser/parse_relation.h" #include "parser/parsetree.h" #include "rewrite/rewriteManip.h" #ifdef PGXC #include "access/sysattr.h" #include "pgxc/pgxc.h" #endif #include "optimizer/streamplan.h" #include "parser/parse_oper.h" #include "utils/lsyscache.h" #include "access/transam.h" #include "catalog/pg_operator.h" #include "nodes/pg_list.h" #include "optimizer/planner.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, Node* all_quals = NULL); static Node* pull_up_sublinks_qual_recurse(PlannerInfo* root, Node* node, Node** jtlink1, Relids *available_rels1, Node** jtlink2, Relids *available_rels2, Node* all_quals = NULL); static Node *pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode, JoinExpr *lowest_outer_join, JoinExpr *lowest_nulling_outer_join, AppendRelInfo *containing_appendrel); static Node* pull_up_simple_subquery(PlannerInfo* root, Node* jtnode, RangeTblEntry* rte, JoinExpr* lowest_outer_join, JoinExpr *lowest_nulling_outer_join, AppendRelInfo* containing_appendrel); static Node* pull_up_simple_union_all(PlannerInfo* root, Node* jtnode, RangeTblEntry* rte); static void pull_up_union_leaf_queries( Node* setOp, PlannerInfo* root, int parentRTindex, Query* setOpQuery, int childRToffset); static void make_setop_translation_list(Query* query, Index newvarno, List** translated_vars); static bool is_simple_lateral_subquery(Query* subquery, JoinExpr *lowest_outer_join); static bool is_simple_subquery(Query* subquery, RangeTblEntry *rte, JoinExpr *lowest_outer_join); static bool is_simple_union_all(Query* subquery); static bool is_simple_union_all_recurse(Node* setOp, Query* setOpQuery, List* colTypes); static bool is_safe_append_member(Query* subquery); static bool jointree_contains_lateral_outer_refs(Node *jtnode, bool restricted, Relids safe_upper_varnos); static void replace_vars_in_jointree(Node* jtnode, pullup_replace_vars_context* context, JoinExpr* lowest_nulling_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 Query *pullup_replace_vars_subquery(Query *query, pullup_replace_vars_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 Node* deleteRelatedNullTest(Node* node, PlannerInfo* root); static Node* reduce_inequality_fulljoins_jointree_recurse(PlannerInfo* root, Node* jtnode); static Node *pull_up_sublinks_targetlist(PlannerInfo *root, Node *node, Node *jtnode, Relids *relids, Node **newTargetList, Node *whereQuals); #ifndef ENABLE_MULTIPLE_NODES static bool find_rownum_in_quals(PlannerInfo *root); static bool contains_swctes(const PlannerInfo *root); #endif /* * replace_empty_jointree * If the Query's jointree is empty, replace it with a dummy RTE_RESULT * relation. * * By doing this, we can avoid a bunch of corner cases that formerly existed * for SELECTs with omitted FROM clauses. An example is that a subquery * with empty jointree previously could not be pulled up, because that would * have resulted in an empty relid set, making the subquery not uniquely * identifiable for join or PlaceHolderVar processing. * * Unlike most other functions in this file, this function doesn't recurse; * we rely on other processing to invoke it on sub-queries at suitable times. */ void replace_empty_jointree(Query *parse) { RangeTblEntry *rte; Index rti; RangeTblRef *rtr; /* Nothing to do if jointree is already nonempty */ if (parse->jointree->fromlist != NIL) return; /* We mustn't change it in the top level of a setop tree, either */ if (parse->setOperations) return; /* Create suitable RTE */ rte = makeNode(RangeTblEntry); rte->rtekind = RTE_RESULT; rte->eref = makeAlias("*RESULT*", NIL); /* Add it to rangetable */ parse->rtable = lappend(parse->rtable, rte); rti = list_length(parse->rtable); /* And jam a reference into the jointree */ rtr = makeNode(RangeTblRef); rtr->rtindex = rti; parse->jointree->fromlist = list_make1(rtr); } #ifndef ENABLE_MULTIPLE_NODES /* * helper function to check if SWCB ctes contaisn in current SubQuery, normally help us to * idenfity if it is OK to appy SWCB related optimization steps */ static bool contains_swctes(const PlannerInfo *root) { if (root->parse == NULL || root->parse->cteList == NIL) { return false; } List *cteList = root->parse->cteList; ListCell *lc = NULL; bool found = false; foreach(lc, cteList) { CommonTableExpr *cte = (CommonTableExpr *)lfirst(lc); /* check if cte from parse->ctelist is a swcb converted */ if (cte->swoptions != NULL) { found = true; break; } } return found; } #endif /* * 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 = NULL; Relids relids; #ifndef ENABLE_MULTIPLE_NODES /* if quals include rownum, forbid pulling up sublinks */ if (find_rownum_in_quals(root)) { return; } /* check existance of SWCB converted */ if (contains_swctes(root)) { return; } #endif /* 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); if ((u_sess->attr.attr_sql.rewrite_rule & SUBLINK_PULLUP_IN_TARGETLIST) && permit_from_rewrite_hint(root, SUBLINK_PULLUP_IN_TARGETLIST)) { /* Begin recursion through the targetlist */ Node *newTargetList = NULL; Node *whereQuals = root->parse->jointree->quals; jtnode = pull_up_sublinks_targetlist(root, (Node *)root->parse->targetList, (Node *)root->parse->jointree, &relids, &newTargetList, whereQuals); /* * 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 (newTargetList != NULL) root->parse->targetList = (List *)replace_node_clause((Node *)root->parse->targetList, (Node *)root->parse->targetList, newTargetList, RNC_REPLACE_FIRST_ONLY); if (IsA(jtnode, FromExpr)) root->parse->jointree = (FromExpr *) jtnode; else root->parse->jointree = makeFromExpr(list_make1(jtnode), NULL); } } /* * @Description: Put this qual to correct place. * @in new_node - New node sublink pull up after. * @in old_node - Old node sublink pull up before. * @in qual - Need set qual clause. * @in old_node_relids - old node available relids. * @return - new node. */ Node* assign_qual_clause(Node* new_node, Node* old_node, Node* qual, Relids old_node_relids) { if (qual == NULL) { return new_node; } Relids qual_varnos = pull_varnos(qual); /* * We need add this quals to new_node if old_node_relids can not include qual_varnos. * than can happend when or_clause pull up. */ if (!bms_is_subset(qual_varnos, old_node_relids)) { if (IsA(new_node, FromExpr)) { ((FromExpr*)new_node)->quals = qual; } else { new_node = (Node*)makeFromExpr(list_make1(new_node), qual); } } /* Only need put qual to old node, this qual can be original(pull up before) qual.*/ else { if (IsA(old_node, FromExpr)) { ((FromExpr*)old_node)->quals = qual; } else { ((JoinExpr*)old_node)->quals = qual; } } bms_free_ext(qual_varnos); return new_node; } /* * 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, Node* all_quals) { 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 = NULL; Node* jtlink = NULL; ListCell* l = NULL; Node* qual = NULL; Relids current_relids = NULL; /* First, recurse to process children and collect their relids */ foreach (l, f->fromlist) { Node* newchild = NULL; Relids childrelids; newchild = pull_up_sublinks_jointree_recurse(root, (Node*)lfirst(l), &childrelids, f->quals); newfromlist = lappend(newfromlist, newchild); /* Keep current available rtindex. */ current_relids = bms_union(current_relids, childrelids); 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 */ qual = pull_up_sublinks_qual_recurse(root, f->quals, &jtlink, &frelids, NULL, NULL, f->quals); /* * Put this qual to correct place. It is mean this qual only need put to * original FromExpr, also can put to new generate jtlink, e.g. or_clause pull up. * * For examlpe: * select * from t1 where exists (select a from t2 where t1.a = t2.a) or * exists (select b from t3 where t1.b = t3.b); * * This query be equivalent to: * * select t1.* from t1 left join (select t2.a from t2 group by t2.a) as tt1 on (t1.a = tt1.a) * left join (select t3.b from t3 group by t3.a) as tt2 on (tt2.b = t1.b) * where tt1.a is not null or tt2.b is not null; * * This case mean qual 'tt1.a is not null or tt2.b is not null' need put to behind all join * instead of behind table t1. */ jtlink = assign_qual_clause(jtlink, (Node*)newf, qual, current_relids); /* * 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 = NULL; Relids leftrelids; Relids rightrelids; Node* jtlink = NULL; Node* quals = NULL; /* * Make a modifiable copy of join node, but don't bother copying its * subnodes (yet). */ j = (JoinExpr*)palloc(sizeof(JoinExpr)); errno_t errorno = memcpy_s(j, sizeof(JoinExpr), jtnode, sizeof(JoinExpr)); securec_check(errorno, "", ""); jtlink = (Node*)j; /* 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); Relids union_relids = bms_union(leftrelids, rightrelids); /* * Now process qual, showing appropriate child relids as available, * and attach any pulled-up jointree items at the right place. In the * inner-join case we put new JoinExprs above the existing one (much * as for a FromExpr-style join). In outer-join cases the new * JoinExprs must go into the nullable side of the outer join. The * point of the available_rels machinations is to ensure that we only * pull up quals for which that's okay. * * We don't expect to see any pre-existing JOIN_SEMI or JOIN_ANTI * nodes here. */ switch (j->jointype) { case JOIN_INNER: quals = pull_up_sublinks_qual_recurse( root, j->quals, &jtlink, &union_relids, NULL, NULL, all_quals); /* * To inner join, we need special manage this quals, else can lead to error * when or_clause be pulled up. * For example: * select 1 from t1 inner join t2 on (exists (select * from t3 where t1.a = t3.a) * or exists (select * from t4 where t2.a = t4.a)); * * This query be equivalent to: * * select 1 from t1 inner join t2 on (1 = 1) * left join (select t3.a from t3 group by t3.a) as tt3 on (t1.a = t3.a) * left join (select t4.a from t4 group by t4.a) as tt4 on t2.a = t4.a) * where tt3.a is not null or tt4.a is not null; * * To this query, return quals is 'tt3.a is not null or tt4.a is not null', * this qual need put to behind all join, can not put to behind t1 join t2 that will lead * to error(JOIN qualification cannot refer to other relations) because can not find tt3.a and tt4.a. */ j->quals = NULL; jtlink = assign_qual_clause(jtlink, (Node*)j, quals, bms_union(leftrelids, rightrelids)); break; case JOIN_LEFT: case JOIN_LEFT_ANTI_FULL: j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->rarg, &rightrelids, NULL, NULL); break; case JOIN_FULL: case JOIN_SEMI: case JOIN_ANTI: if (u_sess->attr.attr_common.log_min_messages <= DEBUG2) { ereport(DEBUG2, (errmodule(MOD_OPT_REWRITE), errmsg("We record join type when semi_join=4 anti_join=5: %d", j->jointype))); } /* can't do anything with full-join quals */ break; case JOIN_RIGHT: case JOIN_RIGHT_ANTI_FULL: j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->larg, &leftrelids, NULL, NULL); break; default: { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized join type: %d", (int)j->jointype))); } break; } /* * 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 { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized node type: %d", (int)nodeTag(jtnode)))); } return jtnode; } /* * Recurse through top-level qual nodes for pull_up_sublinks() * * jtlink1 points to the link in the jointree where any new JoinExprs should * be inserted if they reference available_rels1 (i.e., available_rels1 * denotes the relations present underneath jtlink1). Optionally, jtlink2 can * point to a second link where new JoinExprs should be inserted if they * reference available_rels2 (pass NULL for both those arguments if not used). * Note that SubLinks referencing both sets of variables cannot be optimized. * If we find multiple pull-up-able SubLinks, they'll get stacked onto jtlink1 * and/or jtlink2 in the order we encounter them. We rely on subsequent * optimization to rearrange the stack if appropriate. * * Returns the replacement qual node, or NULL if the qual should be removed. */ static Node* pull_up_sublinks_qual_recurse(PlannerInfo* root, Node* node, Node** jtlink1, Relids *available_rels1, Node** jtlink2, Relids *available_rels2, Node* all_quals) { if (node == NULL) return NULL; if (IsA(node, SubLink)) { SubLink* sublink = (SubLink*)node; JoinExpr* j = NULL; Relids child_rels; if (has_no_expand_hint((Query*)sublink->subselect)) { return node; } /* Is it a convertible ANY or EXISTS clause? */ if (sublink->subLinkType == ANY_SUBLINK) { if ((j = convert_ANY_sublink_to_join(root, sublink, false, *available_rels1)) != NULL) { /* Yes; insert the new join node into the join tree */ j->larg = *jtlink1; *jtlink1 = (Node*)j; /* Recursively process pulled-up jointree nodes */ j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &child_rels); /* * Now recursively process the pulled-up quals. Any inserted * joins can get stacked onto either j->larg or j->rarg, * depending on which rels they reference. */ j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->larg, available_rels1, &j->rarg, &child_rels); /* Return NULL representing constant TRUE */ return NULL; } if (available_rels2 != NULL && (j = convert_ANY_sublink_to_join(root, sublink, false, *available_rels2)) != NULL) { /* Yes; insert the new join node into the join tree */ j->larg = *jtlink2; *jtlink2 = (Node*)j; /* Recursively process pulled-up jointree nodes */ j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &child_rels); /* * Now recursively process the pulled-up quals. Any inserted * joins can get stacked onto either j->larg or j->rarg, * depending on which rels they reference. */ j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->larg, available_rels2, &j->rarg, &child_rels); /* Return NULL representing constant TRUE */ return NULL; } } else if (sublink->subLinkType == EXISTS_SUBLINK) { if ((j = convert_EXISTS_sublink_to_join(root, sublink, false, *available_rels1)) != NULL) { /* Yes; insert the new join node into the join tree */ j->larg = *jtlink1; *jtlink1 = (Node*)j; /* Recursively process pulled-up jointree nodes */ j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &child_rels); /* * Now recursively process the pulled-up quals. Any inserted * joins can get stacked onto either j->larg or j->rarg, * depending on which rels they reference. */ j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->larg, available_rels1, &j->rarg, &child_rels); /* Return NULL representing constant TRUE */ return NULL; } if (available_rels2 != NULL && (j = convert_EXISTS_sublink_to_join(root, sublink, false, *available_rels2)) != NULL) { /* Yes; insert the new join node into the join tree */ j->larg = *jtlink2; *jtlink2 = (Node*)j; /* Recursively process pulled-up jointree nodes */ j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &child_rels); /* * Now recursively process the pulled-up quals. Any inserted * joins can get stacked onto either j->larg or j->rarg, * depending on which rels they reference. */ j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->larg, available_rels2, &j->rarg, &child_rels); /* Return NULL representing constant TRUE */ return NULL; } } return node; } if (not_clause(node)) { /* If the immediate argument of NOT is EXISTS, try to convert */ SubLink* sublink = (SubLink*)get_notclausearg((Expr*)node); JoinExpr* j = NULL; Relids child_rels; if (sublink && IsA(sublink, SubLink)) { if (sublink->subLinkType == EXISTS_SUBLINK) { if ((j = convert_EXISTS_sublink_to_join(root, sublink, true, *available_rels1)) != NULL) { /* Yes; insert the new join node into the join tree */ j->larg = *jtlink1; *jtlink1 = (Node*)j; /* Recursively process pulled-up jointree nodes */ j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &child_rels); /* * Now recursively process the pulled-up quals. Because * we are underneath a NOT, we can't pull up sublinks that * reference the left-hand stuff, but it's still okay to * pull up sublinks referencing j->rarg. */ j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->rarg, &child_rels, NULL, NULL); /* Return NULL representing constant TRUE */ return NULL; } if (available_rels2 != NULL && (j = convert_EXISTS_sublink_to_join(root, sublink, true, *available_rels2)) != NULL) { /* Yes; insert the new join node into the join tree */ j->larg = *jtlink2; *jtlink2 = (Node*)j; /* Recursively process pulled-up jointree nodes */ j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &child_rels); /* * Now recursively process the pulled-up quals. Because * we are underneath a NOT, we can't pull up sublinks that * reference the left-hand stuff, but it's still okay to * pull up sublinks referencing j->rarg. */ j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->rarg, &child_rels, NULL, NULL); /* Return NULL representing constant TRUE */ return NULL; } } else if (sublink->subLinkType == ANY_SUBLINK) { /*support convert not any/in to antijoin*/ if ((j = convert_ANY_sublink_to_join(root, sublink, true, *available_rels1)) != NULL) { /* Now insert the new join node into the join tree */ j->larg = *jtlink1; *jtlink1 = (Node*)j; /* Recursively process pulled-up jointree nodes */ j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &child_rels); /* * Now recursively process the pulled-up quals. Because * we are underneath a NOT, we can't pull up sublinks that * reference the left-hand stuff, but it's still okay to * pull up sublinks referencing j->rarg. */ j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->rarg, &child_rels, NULL, NULL); /* and return NULL representing constant TRUE */ return NULL; } if (available_rels2 != NULL && (j = convert_ANY_sublink_to_join(root, sublink, true, *available_rels2)) != NULL) { /* Yes; insert the new join node into the join tree */ j->larg = *jtlink2; *jtlink2 = (Node*)j; /* Recursively process pulled-up jointree nodes */ j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &child_rels); /* * Now recursively process the pulled-up quals. Because * we are underneath a NOT, we can't pull up sublinks that * reference the left-hand stuff, but it's still okay to * pull up sublinks referencing j->rarg. */ j->quals = pull_up_sublinks_qual_recurse(root, j->quals, &j->rarg, &child_rels, NULL, NULL); /* Return NULL representing constant TRUE */ return NULL; } } } return node; } if (and_clause(node)) { /* Recurse into AND clause */ List* newclauses = NIL; ListCell* l = NULL; foreach (l, ((BoolExpr*)node)->args) { Node* oldclause = (Node*)lfirst(l); Node* newclause = NULL; newclause = pull_up_sublinks_qual_recurse( root, oldclause, jtlink1, available_rels1, jtlink2, available_rels2, all_quals); if (newclause != NULL) newclauses = lappend(newclauses, newclause); } /* We might have got back fewer clauses than we started with */ if (newclauses == NIL) return NULL; else if (list_length(newclauses) == 1) return (Node*)linitial(newclauses); else return (Node*)make_andclause(newclauses); } /* convert or_clause to left join. */ if (or_clause(node)) { convert_ORCLAUSE_to_join(root, (BoolExpr*)node, jtlink1, available_rels1); if (available_rels2 != NULL) { convert_ORCLAUSE_to_join(root, (BoolExpr *)node, jtlink2, available_rels2); } return node; } if(IsA(node, OpExpr) || IsA(node, NullTest)) { List *sublinkList = pull_sublink(node, 0, false); /*Try to pull up these sublink*/ if(sublinkList != NULL) { ListCell *lc = NULL; foreach(lc, sublinkList) { Node *sublink = (Node*)lfirst(lc); if (unlikely(!(IsA(sublink, SubLink)))) ereport(ERROR, (errmodule(MOD_OPT_REWRITE), errcode(ERRCODE_DATATYPE_MISMATCH), errmsg("Node should be SubLink in pull_up_sublinks_qual_recurse"))); /*Return value is changed opexpr*/ node = convert_EXPR_sublink_to_join(root, jtlink1, node, (SubLink*)sublink, available_rels1, all_quals); if (available_rels2 != NULL) { node = convert_EXPR_sublink_to_join(root, jtlink2, node, (SubLink*)sublink, available_rels2, all_quals); } } } return node; } /* Stop if not an AND */ return node; } /* * pull_up_sublinks_targetlist * sublink pull up logic for sublinks in targetlist * * Parameters: * @in root: planner info of current query level * @in node: list of targetlist expression * @in jtnode: from table structure * @in relids: bitmap of relids that is visible to sublink * @in/out newTargetList: converted targetlist * @out: whereQuals: the where quals * * Returns: new formed from table structure */ static Node* pull_up_sublinks_targetlist(PlannerInfo *root, Node *node, Node *jtnode, Relids *relids, Node **newTargetList, Node *whereQuals) { List *sublinkName = pull_sublink(node, 0, true); List *sublinkList = pull_sublink(node, 0, false); ListCell *lc = NULL; ListCell *lc1 = NULL; /* Try to pull up all sublinks got from targetlist */ forboth(lc, sublinkList, lc1, sublinkName) { SubLink *sublink = (SubLink*) lfirst(lc); if (has_no_expand_hint((Query*)sublink->subselect)) { continue; } char *resname = (char*) lfirst(lc1); Assert(IsA(sublink, SubLink)); /* Currently we only support expr sublink */ if (sublink->subLinkType == EXPR_SUBLINK) { /* * Return value is changed opexpr. Since we only modify * the members of opExpr, so the return value can be ignored */ node = convert_EXPR_sublink_to_join(root, &jtnode, node, (SubLink*)sublink, relids, whereQuals, resname); } /* To do: handle of other sublink type */ } /* * The changed targetlist is returned to replace the original targetList. * In this way, the sublink is excluded. */ *newTargetList = node; return jtnode; } /* * 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_sublinks * so that we can inline any functions used in SubLink 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 = NULL; foreach (rt, root->parse->rtable) { RangeTblEntry* rte = (RangeTblEntry*)lfirst(rt); if (rte->rtekind == RTE_FUNCTION) { Query* funcquery = NULL; /* Check safety of expansion, and expand if possible */ funcquery = inline_set_returning_function(root, rte); if (funcquery != NULL) { /* Successful expansion, replace the rtable entry */ rte->rtekind = RTE_SUBQUERY; rte->subquery = funcquery; rte->funcexpr = NULL; rte->funccoltypes = NIL; rte->funccoltypmods = NIL; rte->funccolcollations = NIL; } } } } /* * This recursively processes the jointree and returns a modified jointree. */ Node * pull_up_subqueries(PlannerInfo *root, Node *jtnode) { /* Start off with no containing join nor appendrel */ return pull_up_subqueries_recurse(root, jtnode, NULL, NULL, NULL); } /* * pull_up_subqueries_recurse * Recursive guts of pull_up_subqueries. * * This recursively processes the jointree and returns a modified jointree. * * If this jointree node is within either side of an outer join, then * lowest_outer_join references the lowest such JoinExpr node; otherwise * it is NULL. We use this to constrain the effects of LATERAL subqueries. * * If this jointree node is within the nullable side of an outer join, then * lowest_nulling_outer_join references the lowest such JoinExpr node; * otherwise it is NULL. This forces use of the PlaceHolderVar mechanism for * references to non-nullable targetlist items, but only for references above * that join. * * If we are looking at a member subquery of an append relation, * containing_appendrel describes that relation; else it is NULL. * 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 to maintain * validity of the jointree structure while recursing, in the following sense: * whenever we recurse, all qual expressions in the tree must be reachable * from the top level, in case the recursive call needs to modify them. * * Notice also that we can't turn pullup_replace_vars loose on the whole * jointree, because it'd return a mutated copy of the tree; we have to * invoke it just on the quals, instead. This behavior is what makes it * reasonable to pass lowest_outer_join and lowest_nulling_outer_join as * pointers rather than some more-indirect way of identifying the lowest * OJs. Likewise, we don't replace append_rel_list members but only their * substructure, so the containing_appendrel reference is safe to use. */ Node* pull_up_subqueries_recurse( PlannerInfo* root, Node* jtnode, JoinExpr* lowest_outer_join, JoinExpr *lowest_nulling_outer_join, AppendRelInfo* containing_appendrel) { if (jtnode == NULL) return NULL; #ifndef ENABLE_MULTIPLE_NODES /* if quals include rownum, set hasRownumQual to true */ if(find_rownum_in_quals(root)) { root->hasRownumQual = true; } #endif if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef*)jtnode)->rtindex; RangeTblEntry* rte = rt_fetch(varno, root->parse->rtable); /* Init flag */ rte->subquery_pull_up = false; /* * 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 && is_simple_subquery(rte->subquery, rte, lowest_outer_join) && (containing_appendrel == NULL || is_safe_append_member(rte->subquery))) return pull_up_simple_subquery(root, jtnode, rte, lowest_outer_join, lowest_nulling_outer_join, containing_appendrel); /* * 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.) * * In multi-node group scenario, we should not pull up union all because * the branchs may be in different node group, we could not determine the * group for append path */ if (rte->rtekind == RTE_SUBQUERY && is_simple_union_all(rte->subquery) && #ifndef ENABLE_MULTIPLE_NODES !root->hasRownumQual && #endif (!ng_is_multiple_nodegroup_scenario())) return pull_up_simple_union_all(root, jtnode, rte); /* Otherwise, do nothing at this node. */ } else if (IsA(jtnode, FromExpr)) { FromExpr* f = (FromExpr*)jtnode; ListCell* l = NULL; Assert(containing_appendrel == NULL); foreach (l, f->fromlist) lfirst(l) = pull_up_subqueries_recurse(root, (Node*)lfirst(l), lowest_outer_join, lowest_nulling_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: j->larg = pull_up_subqueries_recurse(root, j->larg, lowest_outer_join, lowest_nulling_outer_join, NULL); j->rarg = pull_up_subqueries_recurse(root, j->rarg, lowest_outer_join, lowest_nulling_outer_join, NULL); break; case JOIN_LEFT: case JOIN_SEMI: case JOIN_ANTI: case JOIN_LEFT_ANTI_FULL: j->larg = pull_up_subqueries_recurse(root, j->larg, lowest_outer_join, lowest_nulling_outer_join, NULL); j->rarg = pull_up_subqueries_recurse(root, j->rarg, j, j, NULL); break; case JOIN_FULL: j->larg = pull_up_subqueries_recurse(root, j->larg, j, j, NULL); j->rarg = pull_up_subqueries_recurse(root, j->rarg, j, j, NULL); break; case JOIN_RIGHT: case JOIN_RIGHT_ANTI_FULL: j->larg = pull_up_subqueries_recurse(root, j->larg, j, j, NULL); j->rarg = pull_up_subqueries_recurse(root, j->rarg, lowest_outer_join, lowest_nulling_outer_join, NULL); break; default: { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized join type: %d", (int)j->jointype))); } break; } } else { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized node type: %d", (int)nodeTag(jtnode)))); } return jtnode; } /* * @Description: Pull up subquery's hint. * @in root: query level info. * @in parse: Parent query. * @in hint_state: Subquery's hint. */ void pull_up_subquery_hint(PlannerInfo* root, Query* parse, HintState* hint_state) { if (parse->hintState == NULL) { parse->hintState = HintStateCreate(); } parse->hintState->join_hint = list_concat(parse->hintState->join_hint, hint_state->join_hint); parse->hintState->leading_hint = list_concat(parse->hintState->leading_hint, hint_state->leading_hint); parse->hintState->row_hint = list_concat(parse->hintState->row_hint, hint_state->row_hint); parse->hintState->stream_hint = list_concat(parse->hintState->stream_hint, hint_state->stream_hint); parse->hintState->scan_hint = list_concat(parse->hintState->scan_hint, hint_state->scan_hint); parse->hintState->hint_warning = list_concat(parse->hintState->hint_warning, hint_state->hint_warning); parse->hintState->skew_hint = list_concat(parse->hintState->skew_hint, hint_state->skew_hint); parse->hintState->nall_hints = parse->hintState->nall_hints + hint_state->nall_hints; parse->hintState->multi_node_hint = hint_state->multi_node_hint; /* no_expand hint, set hint, no_gpc hint should not be pulled up */ if (hint_state->block_name_hint) { BlockNameHint* blockNameHint = (BlockNameHint*)linitial(hint_state->block_name_hint); append_warning_to_list( root, (Hint*)blockNameHint, "Hint%s will become invalid due to sub-query pulling up.", hint_string); hintDelete((Hint*)blockNameHint); list_free_ext(hint_state->block_name_hint); hint_state->block_name_hint = NIL; } } static bool is_subquery_partial_push(PlannerInfo* root, RangeTblEntry* rte) { /* parent cannot push and subquery can push */ if (IS_STREAM_PLAN && !root->parse->can_push && rte->subquery->can_push) { return true; } return false; } /* * 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_recurse. */ static Node* pull_up_simple_subquery(PlannerInfo* root, Node* jtnode, RangeTblEntry* rte, JoinExpr* lowest_outer_join, JoinExpr *lowest_nulling_outer_join, AppendRelInfo* containing_appendrel) { Query* parse = root->parse; int varno = ((RangeTblRef*)jtnode)->rtindex; Query* subquery = NULL; PlannerInfo* subroot = NULL; int rtoffset; pullup_replace_vars_context rvcontext; ListCell* lc = NULL; if (is_subquery_partial_push(root, rte)) { return jtnode; } /* * 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 = (Query*)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; /* * Set simple subquery as subquery of upper level query and change * to the same level after pullup */ subroot->query_level = root->query_level + 1; subroot->parent_root = root; subroot->plan_params = NIL; subroot->planner_cxt = CurrentMemoryContext; subroot->init_plans = NIL; subroot->cte_plan_ids = NIL; subroot->eq_classes = NIL; subroot->append_rel_list = NIL; subroot->rowMarks = NIL; subroot->hasRecursion = false; subroot->qualSecurityLevel = 0; subroot->wt_param_id = -1; subroot->non_recursive_plan = NULL; subroot->hasRownumQual = root->hasRownumQual; /* No CTEs to worry about */ Assert(subquery->cteList == NIL); /* * If the FROM clause is empty, replace it with a dummy RTE_RESULT RTE, so * that we don't need so many special cases to deal with that situation. */ replace_empty_jointree(subquery); /* * Pull up any SubLinks within the subquery's quals, 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 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_recurse(subroot, (Node*)subquery->jointree, NULL, NULL, NULL); /* restore the levels back */ subroot->query_level--; subroot->parent_root = root->parent_root; /* * 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_recurse. */ if (subquery->jointree == NULL) { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED), errmsg("jointree in subquery could not be NULL"))); } if (is_simple_subquery(subquery, rte, lowest_outer_join) && (containing_appendrel == NULL || is_safe_append_member(subquery)) && !has_no_expand_hint(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; } /* * 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); if (subquery->hintState) { /* pull up hint */ pull_up_subquery_hint(root, parse, subquery->hintState); } /* * 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. Set up appropriate context * data for pullup_replace_vars. */ rvcontext.root = root; rvcontext.targetlist = subquery->targetList; rvcontext.target_rte = rte; rvcontext.outer_hasSubLinks = &parse->hasSubLinks; rvcontext.varno = varno; rvcontext.need_phvs = (lowest_nulling_outer_join != NULL || containing_appendrel != NULL); rvcontext.wrap_non_vars = (containing_appendrel != NULL); /* initialize cache array with indexes 0 .. length(tlist) */ rvcontext.rv_cache = (Node**)palloc0((list_length(subquery->targetList) + 1) * sizeof(Node*)); /* * 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 = (List*)pullup_replace_vars((Node*)parse->targetList, &rvcontext); parse->returningList = (List*)pullup_replace_vars((Node*)parse->returningList, &rvcontext); if (parse->upsertClause != NULL) { parse->upsertClause->updateTlist = (List*) pullup_replace_vars((Node*)parse->upsertClause->updateTlist, &rvcontext); } replace_vars_in_jointree((Node*)parse->jointree, &rvcontext, lowest_nulling_outer_join); { ListCell* l = NULL; foreach (l, parse->mergeActionList) { MergeAction* action = (MergeAction*)lfirst(l); /* * We only replace targetlist and qual in pgxc and single node mode. For stream * plan, we don't replace the targetlist and qual, since during plan reference, it'll * referred to parse->mergeSourceTargetList, which is not replaced in this * procedure. * XXXX: Replace the mergeSourceTargetList and then targetlist and qual at the * same time. However, we need placeholder for this, since for sublink, we'll * generate different subplans (with different paramid) for different expression, * and it's also can't be referred. */ if (!IS_PGXC_DATANODE && !IS_STREAM_PLAN && !IS_SINGLE_NODE) { action->targetList = (List*)pullup_replace_vars((Node*)action->targetList, &rvcontext); action->qual = pullup_replace_vars((Node*)action->qual, &rvcontext); } else { action->pulluped_targetList = (List*)pullup_replace_vars((Node*)action->targetList, &rvcontext); } } } Assert(parse->setOperations == NULL); parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext); /* * 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 (lc, root->append_rel_list) { AppendRelInfo* appinfo = (AppendRelInfo*)lfirst(lc); 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 (lc, parse->rtable) { RangeTblEntry* otherrte = (RangeTblEntry*)lfirst(lc); if (otherrte->rtekind == RTE_JOIN) otherrte->joinaliasvars = (List*)pullup_replace_vars((Node*)otherrte->joinaliasvars, &rvcontext); } /* * If the subquery had a LATERAL marker, propagate that to any of its * child RTEs that could possibly now contain lateral cross-references. * The children might or might not contain any actual lateral * cross-references, but we have to mark the pulled-up child RTEs so that * later planner stages will check for such. * * NB: although the parser only sets the lateral flag in subquery and * function RTEs, after this step it can also be set in VALUES RTEs. */ if (rte->lateral) { foreach(lc, subquery->rtable) { RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(lc); switch (child_rte->rtekind) { case RTE_SUBQUERY: case RTE_FUNCTION: case RTE_VALUES: child_rte->lateral = true; break; case RTE_RELATION: case RTE_JOIN: case RTE_CTE: case RTE_RESULT: case RTE_REMOTE_DUMMY: /* these can't contain any lateral references */ break; } } } foreach(lc, subquery->rtable) { RangeTblEntry *rte = (RangeTblEntry *)lfirst(lc); rte->pulled_from_subquery = true; } /* * 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); /* Subquery can be pull, so set flag to true. */ rte->subquery_pull_up = true; /* * 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); /* * We also have to fix the relid sets of any 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 * PlaceHolderVar nodes just created by pullup_replace_vars() will be * adjusted, so having created them with the subquery's varno is correct. * * Likewise, relids appearing in AppendRelInfo nodes have to be fixed. 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->lateral_info_list == NIL); Assert(subroot->lateral_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 = parse->hasSubLinks || subquery->hasSubLinks; /* If subquery had any RLS conditions, now main query does too */ parse->hasRowSecurity = parse->hasRowSecurity || subquery->hasRowSecurity; /* * subquery won't be pulled up if it hasAggs or hasWindowFuncs, so no work * needed on those flags * * Return the adjusted subquery jointree to replace the RangeTblRef entry * in parent's jointree; or, if the FromExpr is degenerate, just return * its single member. */ Assert(IsA(subquery->jointree, FromExpr)); Assert(subquery->jointree->fromlist != NIL); if (subquery->jointree->quals == NULL && list_length(subquery->jointree->fromlist) == 1) return (Node *) linitial(subquery->jointree->fromlist); return (Node*)subquery->jointree; } /* * pull_up_simple_union_all * Pull up a single simple UNION ALL subquery. * * jtnode is a RangeTblRef that has been identified as a simple UNION ALL * subquery by pull_up_subqueries. We pull up the leaf subqueries and * build an "append relation" for the union set. The result value is just * jtnode, since we don't actually need to change the query jointree. */ static Node* pull_up_simple_union_all(PlannerInfo* root, Node* jtnode, RangeTblEntry* rte) { int varno = ((RangeTblRef*)jtnode)->rtindex; Query* subquery = rte->subquery; int rtoffset; List* rtable = NIL; UNIONALL_SHIPPING_TYPE shipping_type = SHIPPING_NONE; if (subquery->setOperations == NULL) { elog(ERROR, "subquery's setOperations tree should not be NULL in pull_up_simple_union_all"); } if (IS_STREAM_PLAN) { shipping_type = precheck_shipping_union_all(subquery, subquery->setOperations); if (shipping_type == SHIPPING_ALL && subquery->can_push == false) { shipping_type = SHIPPING_PARTIAL; } if (shipping_type == SHIPPING_ALL) { if (!root->parse->can_push) { return jtnode; } } else if (shipping_type == SHIPPING_PARTIAL) { return jtnode; } else { if (root->parse->can_push && check_base_rel_in_fromlist(root->parse, jtnode)) { return jtnode; } } } /* * Append child RTEs to parent rtable. * * Upper-level vars in subquery are now one level closer to their parent * than before. We don't have to worry about offsetting varnos, though, * because any such vars must refer to stuff above the level of the query * we are pulling into. */ rtoffset = list_length(root->parse->rtable); rtable = (List*)copyObject(subquery->rtable); IncrementVarSublevelsUp_rtable(rtable, -1, 1); root->parse->rtable = list_concat(root->parse->rtable, rtable); /* Subquery can be pull, so set flag to true. */ rte->subquery_pull_up = true; /* * Recursively scan the subquery's setOperations tree and add * AppendRelInfo nodes for leaf subqueries to the parent's * append_rel_list. Also apply pull_up_subqueries to the leaf subqueries. */ AssertEreport(subquery->setOperations != NULL, MOD_OPT_REWRITE, "subquery's setOperations tree should not be NULL in pull_up_simple_union_all"); pull_up_union_leaf_queries(subquery->setOperations, root, varno, subquery, rtoffset); /* * Mark the parent as an append relation. */ rte->inh = true; /* Mark can_push flag of parent's parse. */ if (IS_STREAM_PLAN && root->parse->can_push) { if (shipping_type == SHIPPING_NONE && check_base_rel_in_fromlist(root->parse, jtnode)) set_stream_off(); } return jtnode; } /* * pull_up_union_leaf_queries -- recursive guts of pull_up_simple_union_all * * Build an AppendRelInfo for each leaf query in the setop tree, and then * apply pull_up_subqueries to the leaf query. * * Note that setOpQuery is the Query containing the setOp node, whose tlist * contains references to all the setop output columns. When called from * pull_up_simple_union_all, this is *not* the same as root->parse, which is * the parent Query we are pulling up into. * * parentRTindex is the appendrel parent's index in root->parse->rtable. * * The child RTEs have already been copied to the parent. childRToffset * tells us where in the parent's range table they were copied. When called * from flatten_simple_union_all, childRToffset is 0 since the child RTEs * were already in root->parse->rtable and no RT index adjustment is needed. */ static void pull_up_union_leaf_queries( Node* setOp, PlannerInfo* root, int parentRTindex, Query* setOpQuery, int childRToffset) { if (IsA(setOp, RangeTblRef)) { RangeTblRef* rtr = (RangeTblRef*)setOp; int childRTindex; AppendRelInfo* appinfo = NULL; /* * Calculate the index in the parent's range table */ childRTindex = childRToffset + rtr->rtindex; /* * Build a suitable AppendRelInfo, and attach to parent's list. */ appinfo = makeNode(AppendRelInfo); appinfo->parent_relid = parentRTindex; appinfo->child_relid = childRTindex; appinfo->parent_reltype = InvalidOid; appinfo->child_reltype = InvalidOid; make_setop_translation_list(setOpQuery, childRTindex, &appinfo->translated_vars); appinfo->parent_reloid = InvalidOid; root->append_rel_list = lappend(root->append_rel_list, appinfo); /* * Recursively apply pull_up_subqueries to the new child RTE. (We * must build the AppendRelInfo first, because this will modify it.) * Note that we can pass NULL for containing-join info even if we're * actually under an outer join, because the child's expressions * aren't going to propagate up above the join. */ rtr = makeNode(RangeTblRef); rtr->rtindex = childRTindex; (void)pull_up_subqueries_recurse(root, (Node*)rtr, NULL, NULL, appinfo); } else if (IsA(setOp, SetOperationStmt)) { SetOperationStmt* op = (SetOperationStmt*)setOp; /* Recurse to reach leaf queries */ pull_up_union_leaf_queries(op->larg, root, parentRTindex, setOpQuery, childRToffset); pull_up_union_leaf_queries(op->rarg, root, parentRTindex, setOpQuery, childRToffset); } else { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized node type: %d", (int)nodeTag(setOp)))); } } /* * make_setop_translation_list * Build the list of translations from parent Vars to child Vars for * a UNION ALL member. (At this point it's just a simple list of * referencing Vars, but if we succeed in pulling up the member * subquery, the Vars will get replaced by pulled-up expressions.) */ static void make_setop_translation_list(Query* query, Index newvarno, List** translated_vars) { List* vars = NIL; ListCell* l = NULL; foreach (l, query->targetList) { TargetEntry* tle = (TargetEntry*)lfirst(l); if (tle->resjunk) continue; vars = lappend(vars, makeVarFromTargetEntry(newvarno, tle)); } *translated_vars = vars; } /* * is_simple_lateral_subquery * If the subquery is LATERAL, check for pullup restrictions from that. */ static bool is_simple_lateral_subquery(Query* subquery, JoinExpr *lowest_outer_join) { bool restricted = false; Relids safe_upper_varnos = NULL; /* * The subquery's WHERE and JOIN/ON quals mustn't contain any lateral * references to rels outside a higher outer join (including the case * where the outer join is within the subquery itself). In such a * case, pulling up would result in a situation where we need to * postpone quals from below an outer join to above it, which is * probably completely wrong and in any case is a complication that * doesn't seem worth addressing at the moment. */ if (lowest_outer_join != NULL) { restricted = true; safe_upper_varnos = get_relids_in_jointree((Node *) lowest_outer_join, true); } else { restricted = false; safe_upper_varnos = NULL; /* doesn't matter */ } if (jointree_contains_lateral_outer_refs((Node *) subquery->jointree, restricted, safe_upper_varnos)) return false; /* * If there's an outer join above the LATERAL subquery, also disallow * pullup if the subquery's targetlist has any references to rels * outside the outer join, since these might get pulled into quals * above the subquery (but in or below the outer join) and then lead * to qual-postponement issues similar to the case checked for above. * (We wouldn't need to prevent pullup if no such references appear in * outer-query quals, but we don't have enough info here to check * that. Also, maybe this restriction could be removed if we forced * such refs to be wrapped in PlaceHolderVars, even when they're below * the nearest outer join? But it's a pretty hokey usage, so not * clear this is worth sweating over.) */ if (lowest_outer_join != NULL) { Relids lvarnos = pull_varnos_of_level((Node *) subquery->targetList, 1); if (!bms_is_subset(lvarnos, safe_upper_varnos)) return false; } return true; } static bool is_grouping_subquery(Query* subquery) { /* * Can't pull up a subquery involving grouping, aggregation, sorting, * limiting, or WITH. (XXX WITH could possibly be allowed later) * * We also don't pull up a subquery that has explicit FOR UPDATE/SHARE * clauses, because pullup would cause the locking to occur semantically * higher than it should. Implicit FOR UPDATE/SHARE is okay because in * that case the locking was originally declared in the upper query * anyway. */ if (subquery->hasAggs || subquery->hasWindowFuncs || subquery->groupClause || subquery->groupingSets || subquery->havingQual || subquery->sortClause || subquery->distinctClause || subquery->limitOffset || subquery->limitCount || subquery->hasForUpdate || subquery->cteList) return false; return true; } /* * is_simple_subquery * Check a subquery in the range table to see if it's simple enough * to pull up into the parent query. * rte is the RTE_SUBQUERY RangeTblEntry that contained the subquery. * (Note subquery is not necessarily equal to rte->subquery; it could be a * processed copy of that.) * lowest_outer_join is the lowest outer join above the subquery, or NULL. */ static bool is_simple_subquery(Query* subquery, RangeTblEntry *rte, JoinExpr *lowest_outer_join) { /* * Let's just make sure it's a valid subselect ... */ if (!IsA(subquery, Query) || subquery->commandType != CMD_SELECT || subquery->utilityStmt != NULL) ereport( ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_OPTIMIZER_INCONSISTENT_STATE), (errmsg("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; /* simple subquery cannot related to any grouping info. */ if (!is_grouping_subquery(subquery)) return false; /* * Don't pull up if the RTE represents a security-barrier view; we couldn't * prevent information leakage once the RTE's Vars are scattered about in * the upper query. */ if (rte->security_barrier) return false; if (ContainRownumQual(subquery)) { return false; } if (subquery->hasAggs || subquery->hasWindowFuncs || subquery->groupClause || subquery->groupingSets || subquery->havingQual || subquery->sortClause || subquery->distinctClause || subquery->limitOffset || subquery->limitCount || subquery->hasForUpdate || subquery->cteList) return false; /* * If the subquery is LATERAL, check for pullup restrictions from that. */ if (rte->lateral && !is_simple_lateral_subquery(subquery, lowest_outer_join)) { return false; } #ifndef ENABLE_MULTIPLE_NODES if (ContainRownumQual(subquery)) { return false; } #endif /* * 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 is_simple_union_all(Query* subquery) { SetOperationStmt* topop = NULL; /* Let's just make sure it's a valid subselect ... */ if (!IsA(subquery, Query) || subquery->commandType != CMD_SELECT || subquery->utilityStmt != NULL) ereport( ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_OPTIMIZER_INCONSISTENT_STATE), (errmsg("subquery is bogus")))); /* Is it a set-operation query at all? */ topop = (SetOperationStmt*)subquery->setOperations; if (topop == NULL) return false; AssertEreport( IsA(topop, SetOperationStmt), MOD_OPT_REWRITE, "subquery's setOperations mismatch in is_simple_union_all"); #ifndef ENABLE_MULTIPLE_NODES if (ContainRownumQual(subquery)) { return false; } #endif /* 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; AssertEreport(subquery != NULL, MOD_OPT_REWRITE, "subquery should not be NULL in is_simple_union_all_recurse"); /* Leaf nodes are OK if they match the toplevel column types */ /* We don't have to compare typmods or collations 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 { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("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 = NULL; /* * 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 = (FromExpr*)linitial(jtnode->fromlist); } if (!IsA(jtnode, RangeTblRef)) return false; return true; } /* * jointree_contains_lateral_outer_refs * Check for disallowed lateral references in a jointree's quals * * If restricted is false, all level-1 Vars are allowed (but we still must * search the jointree, since it might contain outer joins below which there * will be restrictions). If restricted is true, return TRUE when any qual * in the jointree contains level-1 Vars coming from outside the rels listed * in safe_upper_varnos. */ static bool jointree_contains_lateral_outer_refs(Node *jtnode, bool restricted, Relids safe_upper_varnos) { if (jtnode == NULL) return false; if (IsA(jtnode, RangeTblRef)) return false; else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l = NULL; /* First, recurse to check child joins */ foreach(l, f->fromlist) { if (jointree_contains_lateral_outer_refs((Node *)lfirst(l), restricted, safe_upper_varnos)) return true; } /* Then check the top-level quals */ if (restricted && !bms_is_subset(pull_varnos_of_level(f->quals, 1), safe_upper_varnos)) return true; } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; /* * If this is an outer join, we mustn't allow any upper lateral * references in or below it. */ if (j->jointype != JOIN_INNER) { restricted = true; safe_upper_varnos = NULL; } /* Check the child joins */ if (jointree_contains_lateral_outer_refs(j->larg, restricted, safe_upper_varnos)) return true; if (jointree_contains_lateral_outer_refs(j->rarg, restricted, safe_upper_varnos)) return true; /* Check the JOIN's qual clauses */ if (restricted && !bms_is_subset(pull_varnos_of_level(j->quals, 1), safe_upper_varnos)) return true; } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return false; } /* * 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 at or below lowest_nulling_outer_join, we can suppress use of * PlaceHolderVars wrapped around the replacement expressions. */ static void replace_vars_in_jointree(Node* jtnode, pullup_replace_vars_context* context, JoinExpr* lowest_nulling_outer_join) { if (jtnode == NULL) return; if (IsA(jtnode, RangeTblRef)) { /* * If the RangeTblRef refers to a LATERAL subquery (that isn't the * same subquery we're pulling up), it might contain references to the * target subquery, which we must replace. We drive this from the * jointree scan, rather than a scan of the rtable, for a couple of * reasons: we can avoid processing no-longer-referenced RTEs, and we * can use the appropriate setting of need_phvs depending on whether * the RTE is above possibly-nulling outer joins or not. */ int varno = ((RangeTblRef *) jtnode)->rtindex; if (varno != context->varno) /* ignore target subquery itself */ { RangeTblEntry *rte = rt_fetch(varno, context->root->parse->rtable); Assert(rte != context->target_rte); if (rte->lateral) { switch (rte->rtekind) { case RTE_SUBQUERY: rte->subquery = pullup_replace_vars_subquery(rte->subquery, context); break; case RTE_FUNCTION: rte->funcexpr = pullup_replace_vars(rte->funcexpr, context); break; case RTE_VALUES: rte->values_lists = (List *) pullup_replace_vars((Node *) rte->values_lists, context); break; case RTE_RELATION: case RTE_JOIN: case RTE_CTE: case RTE_RESULT: /* these shouldn't be marked LATERAL */ Assert(false); break; #ifdef PGXC case RTE_REMOTE_DUMMY: break; #endif } } } } else if (IsA(jtnode, FromExpr)) { FromExpr* f = (FromExpr*)jtnode; ListCell* l = NULL; foreach (l, f->fromlist) replace_vars_in_jointree((Node*)lfirst(l), context, lowest_nulling_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_nulling_outer_join) { /* no more PHVs in or below this join */ context->need_phvs = false; lowest_nulling_outer_join = NULL; } replace_vars_in_jointree(j->larg, context, lowest_nulling_outer_join); replace_vars_in_jointree(j->rarg, context, lowest_nulling_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 { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("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 = NULL; /* * 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 = (Node*)copyObject(rcon->rv_cache[varattno]); } else if (varattno == InvalidAttrNumber) { /* Must expand whole-tuple reference into RowExpr */ RowExpr* rowexpr = NULL; List* colnames = NIL; List* fields = NIL; 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] = (Node*)copyObject(newnode); } } #ifdef PGXC else if (varattno == XC_NodeIdAttributeNumber) { /* We don't need to change the entry for xc_node_id */ newnode = NULL; } #endif else { /* Normal case referencing one targetlist element */ TargetEntry* tle = get_tle_by_resno(rcon->targetlist, varattno); if (tle == NULL) /* shouldn't happen */ ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED), (errmsg("could not find attribute %d in subquery targetlist", varattno)))); /* Make a copy of the tlist item to return */ newnode = (Node*)copyObject(tle->expr); /* Insert PlaceHolderVar if needed */ if (rcon->need_phvs) { bool wrap = false; if (newnode && IsA(newnode, Var) && ((Var*)newnode)->varlevelsup == 0) { /* Simple Vars always escape being wrapped */ wrap = false; } else if (newnode && IsA(newnode, PlaceHolderVar) && ((PlaceHolderVar*)newnode)->phlevelsup == 0) { /* No need to wrap a PlaceHolderVar with another one, either */ 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 so * we don't need to insert a PlaceHolderVar. * * This analysis could be tighter: in particular, a non-strict * construct hidden within a lower-level PlaceHolderVar is not * reason to add another PHV. But for now it doesn't seem * worth the code to be more exact. * * Note: in future maybe we should insert a PlaceHolderVar * anyway, if the 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] = (Node*)copyObject(newnode); } } /* Must adjust varlevelsup if tlist item is from higher query */ if (var->varlevelsup > 0) IncrementVarSublevelsUp(newnode, var->varlevelsup, 0); return newnode; } /* * Apply pullup variable replacement to a subquery * * This needs to be different from pullup_replace_vars() because * replace_rte_variables will think that it shouldn't increment sublevels_up * before entering the Query; so we need to call it with sublevels_up == 1. */ static Query * pullup_replace_vars_subquery(Query *query, pullup_replace_vars_context *context) { Assert(IsA(query, Query)); return (Query *) replace_rte_variables((Node *) query, context->varno, 1, pullup_replace_vars_callback, (void *) context, NULL); } /* * flatten_simple_union_all * Try to optimize top-level UNION ALL structure into an appendrel * * If a query's setOperations tree consists entirely of simple UNION ALL * operations, flatten it into an append relation, which we can process more * intelligently than the general setops case. Otherwise, do nothing. * * In most cases, this can succeed only for a top-level query, because for a * subquery in FROM, the parent query's invocation of pull_up_subqueries would * already have flattened the UNION via pull_up_simple_union_all. But there * are a few cases we can support here but not in that code path, for example * when the subquery also contains ORDER BY. */ void flatten_simple_union_all(PlannerInfo* root) { Query* parse = root->parse; SetOperationStmt* topop = NULL; Node* leftmostjtnode = NULL; int leftmostRTI = 0; RangeTblEntry* leftmostRTE = NULL; int childRTI; RangeTblEntry* childRTE = NULL; RangeTblRef* rtr = NULL; /* Shouldn't be called unless query has setops */ topop = (SetOperationStmt*)parse->setOperations; AssertEreport(topop != NULL && IsA(topop, SetOperationStmt), MOD_OPT_REWRITE, "SetOperationStmt shouldn't be NULL in flatten_simple_union_all"); /* Can't optimize away a recursive UNION */ if (root->hasRecursion) return; /* * Recursively check the tree of set operations. If not all UNION ALL * with identical column types, punt. * * In multi-node group scenario, we should not flatten union all because * the branchs may be in different node group, we could not determine the * group for append path */ if (!is_simple_union_all_recurse((Node*)topop, parse, topop->colTypes) || ng_is_multiple_nodegroup_scenario()) return; /* * Locate the leftmost leaf query in the setops tree. The upper query's * Vars all refer to this RTE (see transformSetOperationStmt). */ leftmostjtnode = topop->larg; while (leftmostjtnode && IsA(leftmostjtnode, SetOperationStmt)) leftmostjtnode = ((SetOperationStmt*)leftmostjtnode)->larg; if (leftmostjtnode && IsA(leftmostjtnode, RangeTblRef)) { leftmostRTI = ((RangeTblRef*)leftmostjtnode)->rtindex; leftmostRTE = rt_fetch(leftmostRTI, parse->rtable); AssertEreport(leftmostRTE->rtekind == RTE_SUBQUERY, MOD_OPT_REWRITE, "leftmostRTE should be SUBQUERY in flatten_simple_union_all"); } else { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_OPTIMIZER_INCONSISTENT_STATE), (errmsg("RangeTblRef not found.")))); } /* * Make a copy of the leftmost RTE and add it to the rtable. This copy * will represent the leftmost leaf query in its capacity as a member of * the appendrel. The original will represent the appendrel as a whole. * (We must do things this way because the upper query's Vars have to be * seen as referring to the whole appendrel.) */ childRTE = (RangeTblEntry*)copyObject(leftmostRTE); parse->rtable = lappend(parse->rtable, childRTE); childRTI = list_length(parse->rtable); /* Modify the setops tree to reference the child copy */ ((RangeTblRef*)leftmostjtnode)->rtindex = childRTI; /* Modify the formerly-leftmost RTE to mark it as an appendrel parent */ leftmostRTE->inh = true; /* * Form a RangeTblRef for the appendrel, and insert it into FROM. The top * Query of a setops tree should have had an empty FromClause initially. */ rtr = makeNode(RangeTblRef); rtr->rtindex = leftmostRTI; AssertEreport(parse->jointree->fromlist == NIL, MOD_OPT_REWRITE, "The top Query of a setops tree should have had an empty FromClause in flatten_simple_union_all"); parse->jointree->fromlist = list_make1(rtr); /* * Now pretend the query has no setops. We must do this before trying to * do subquery pullup, because of Assert in pull_up_simple_subquery. */ parse->setOperations = NULL; /* * Build AppendRelInfo information, and apply pull_up_subqueries to the * leaf queries of the UNION ALL. (We must do that now because they * weren't previously referenced by the jointree, and so were missed by * the main invocation of pull_up_subqueries.) */ pull_up_union_leaf_queries((Node*)topop, root, leftmostRTI, parse, 0); } /* * @Description: Delete not Null Test if var type have not null constraint. * @in node: Qual cluase. * @in qry: Query tree. * @return: return the remaining node. */ static Node* deleteRelatedNullTest(Node* node, PlannerInfo* root) { if (node == NULL) { return NULL; } if (or_clause(node)) { BoolExpr* bool_node = (BoolExpr*)node; ListCell* cell = NULL; foreach (cell, bool_node->args) { /* * If or clause exists 'not null test' can be deleted, then this or clause can all deleted. * That is bescuse 'not null test' is always true. */ Node* result = deleteRelatedNullTest((Node*)lfirst(cell), root); if (result == NULL) { return NULL; } } } else if (and_clause(node)) { BoolExpr* bool_node = (BoolExpr*)node; bool_node->args = (List*)deleteRelatedNullTest((Node*)bool_node->args, root); /* * If and clause exists 'not null test' BOTH can be deleted, then this and clause can be deleted. * That is bescuse BOTH 'not null test' are always true. */ if (bool_node->args == NULL) return NULL; } else if (IsA(node, List)) { List* args_list = NIL; List* l = (List*)node; ListCell* cell = NULL; foreach (cell, l) { Node* result = deleteRelatedNullTest((Node*)lfirst(cell), root); if (result != NULL) { args_list = lappend(args_list, result); } } return (Node*)args_list; } else if (IsA(node, NullTest)) { /* Check this not null test can be deleted. */ NullTest* NullExpr = (NullTest*)node; if (IS_NOT_NULL == NullExpr->nulltesttype && IsA(NullExpr->arg, Var)) { Var* var = (Var*)NullExpr->arg; /* If do not find primary key informatinal constraint, try not null constraint */ if (check_var_nonnullable(root->parse, (Node*)var)) { return NULL; } } } return node; } /* * @Description: Delete related NullTest. * @in parse: The Query Tree after parsing for SQL. */ void removeNotNullTest(PlannerInfo* root) { Query* parse = root->parse; /* Just now, we only support single table optimization */ if (list_length(parse->rtable) == 1) { RangeTblEntry* rte = (RangeTblEntry*)linitial(parse->rtable); if (rte->rtekind == RTE_RELATION) { parse->jointree->quals = deleteRelatedNullTest(parse->jointree->quals, root); } } } /* * 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 = NULL; /* * 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) ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_OPTIMIZER_INCONSISTENT_STATE), (errmsg("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 = NULL; 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; ListCell* l = NULL; foreach (l, f->fromlist) { reduce_outer_joins_state* sub_state = NULL; sub_state = reduce_outer_joins_pass1((Node*)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 = NULL; /* 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); } else { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("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) { /* * 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) ereport( ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED), (errmsg("reached empty jointree")))); if (IsA(jtnode, RangeTblRef)) ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), (errmsg("reached base rel")))); else if (IsA(jtnode, FromExpr)) { FromExpr* f = (FromExpr*)jtnode; ListCell* l = NULL; ListCell* s = NULL; Relids pass_nonnullable_rels; List* pass_nonnullable_vars = NIL; List* pass_forced_null_vars = NIL; /* 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 */ AssertEreport(list_length(f->fromlist) == list_length(state->sub_states), MOD_OPT_REWRITE, "list length mismatch in reduce_outer_joins_pass2"); forboth(l, f->fromlist, s, state->sub_states) { reduce_outer_joins_state* sub_state = (reduce_outer_joins_state*)lfirst(s); if (sub_state->contains_outer) reduce_outer_joins_pass2((Node*)lfirst(l), sub_state, root, pass_nonnullable_rels, pass_nonnullable_vars, pass_forced_null_vars); } bms_free_ext(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 = (reduce_outer_joins_state*)linitial(state->sub_states); reduce_outer_joins_state* right_state = (reduce_outer_joins_state*)lsecond(state->sub_states); 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_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. */ case JOIN_LEFT_ANTI_FULL: case JOIN_RIGHT_ANTI_FULL: /* * This should happened, since they are introduced by full join * conversion, and before that, reduce outer has already be done */ break; default: { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("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 || jointype == JOIN_RIGHT_ANTI_FULL) { Node* tmparg = NULL; tmparg = j->larg; j->larg = j->rarg; j->rarg = tmparg; if (jointype == JOIN_RIGHT) jointype = JOIN_LEFT; else jointype = JOIN_LEFT_ANTI_FULL; right_state = (reduce_outer_joins_state*)linitial(state->sub_states); left_state = (reduce_outer_joins_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 = NIL; 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); AssertEreport(rte->rtekind == RTE_JOIN, MOD_OPT_REWRITE, "RangeTblEntry should be kind of JOIN in reduce_outer_joins_pass2"); AssertEreport( rte->jointype == j->jointype, MOD_OPT_REWRITE, "jointype mismatch in reduce_outer_joins_pass2"); rte->jointype = jointype; } j->jointype = jointype; /* Only recurse if there's more to do below here */ if (left_state->contains_outer || right_state->contains_outer) { Relids local_nonnullable_rels; List* local_forced_null_vars = NIL; Relids pass_nonnullable_rels; List* pass_nonnullable_vars = NIL; List* pass_forced_null_vars = NIL; /* * 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. * * Note that a SEMI join works like an inner join here: it's okay * to pass down both local and upper constraints. (There can't be * any upper constraints affecting its inner side, but it's not * worth having a separate code path to avoid passing them.) * * 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 || jointype == JOIN_SEMI) { /* 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 or 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); } bms_free_ext(local_nonnullable_rels); } } else { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized node type: %d", (int)nodeTag(jtnode)))); } } /* * remove_useless_result_rtes * Attempt to remove RTE_RESULT RTEs from the join tree. * * We can remove RTE_RESULT entries from the join tree using the knowledge * that RTE_RESULT returns exactly one row and has no output columns. Hence, * if one is inner-joined to anything else, we can delete it. Optimizations * are also possible for some outer-join cases, as detailed below. * * Some of these optimizations depend on recognizing empty (constant-true) * quals for FromExprs and JoinExprs. That makes it useful to apply this * optimization pass after expression preprocessing, since that will have * eliminated constant-true quals, allowing more cases to be recognized as * optimizable. What's more, the usual reason for an RTE_RESULT to be present * is that we pulled up a subquery or VALUES clause, thus very possibly * replacing Vars with constants, making it more likely that a qual can be * reduced to constant true. Also, because some optimizations depend on * the outer-join type, it's best to have done reduce_outer_joins() first. * * A PlaceHolderVar referencing an RTE_RESULT RTE poses an obstacle to this * process: we must remove the RTE_RESULT's relid from the PHV's phrels, but * we must not reduce the phrels set to empty. If that would happen, and * the RTE_RESULT is an immediate child of an outer join, we have to give up * and not remove the RTE_RESULT: there is noplace else to evaluate the * PlaceHolderVar. (That is, in such cases the RTE_RESULT *does* have output * columns.) But if the RTE_RESULT is an immediate child of an inner join, * we can change the PlaceHolderVar's phrels so as to evaluate it at the * inner join instead. This is OK because we really only care that PHVs are * evaluated above or below the correct outer joins. * * We used to try to do this work as part of pull_up_subqueries() where the * potentially-optimizable cases get introduced; but it's way simpler, and * more effective, to do it separately. */ void remove_useless_result_rtes(PlannerInfo *root) { ListCell *cell; ListCell *prev; ListCell *next; /* Top level of jointree must always be a FromExpr */ Assert(IsA(root->parse->jointree, FromExpr)); /* Recurse ... */ root->parse->jointree = (FromExpr *) remove_useless_results_recurse(root, (Node *) root->parse->jointree); /* We should still have a FromExpr */ Assert(IsA(root->parse->jointree, FromExpr)); /* * Remove any PlanRowMark referencing an RTE_RESULT RTE. We obviously * must do that for any RTE_RESULT that we just removed. But one for a * RTE that we did not remove can be dropped anyway: since the RTE has * only one possible output row, there is no need for EPQ to mark and * restore that row. * * It's necessary, not optional, to remove the PlanRowMark for a surviving * RTE_RESULT RTE; otherwise we'll generate a whole-row Var for the * RTE_RESULT, which the executor has no support for. */ prev = NULL; for (cell = list_head(root->rowMarks); cell; cell = next) { PlanRowMark *rc = (PlanRowMark *) lfirst(cell); next = lnext(cell); if (rt_fetch(rc->rti, root->parse->rtable)->rtekind == RTE_RESULT) root->rowMarks = list_delete_cell(root->rowMarks, cell, prev); else prev = cell; } } /* * get_result_relid * If jtnode is a RangeTblRef for an RTE_RESULT RTE, return its relid; * otherwise return 0. */ int get_result_relid(PlannerInfo *root, Node *jtnode) { int varno; if (!IsA(jtnode, RangeTblRef)) return 0; varno = ((RangeTblRef *) jtnode)->rtindex; if (rt_fetch(varno, root->parse->rtable)->rtekind != RTE_RESULT) return 0; return varno; } /* * remove_result_refs * Helper routine for dropping an unneeded RTE_RESULT RTE. * * This doesn't physically remove the RTE from the jointree, because that's * more easily handled in remove_useless_results_recurse. What it does do * is the necessary cleanup in the rest of the tree: we must adjust any PHVs * that may reference the RTE. Be sure to call this at a point where the * jointree is valid (no disconnected nodes). * * Note that we don't need to process the append_rel_list, since RTEs * referenced directly in the jointree won't be appendrel members. * * varno is the RTE_RESULT's relid. * newjtloc is the jointree location at which any PHVs referencing the * RTE_RESULT should be evaluated instead. */ void remove_result_refs(PlannerInfo *root, int varno, Node *newjtloc) { /* Fix up PlaceHolderVars as needed */ /* If there are no PHVs anywhere, we can skip this bit */ if (root->glob->lastPHId != 0) { Relids subrelids; subrelids = get_relids_in_jointree(newjtloc, false); Assert(!bms_is_empty(subrelids)); substitute_multiple_relids((Node *) root->parse, varno, subrelids); } /* * We also need to remove any PlanRowMark referencing the RTE, but we * postpone that work until we return to remove_useless_result_rtes. */ } bool find_dependent_phvs_walker(Node *node, find_dependent_phvs_context *context) { if (node == NULL) return false; if (IsA(node, PlaceHolderVar)) { PlaceHolderVar *phv = (PlaceHolderVar *) node; if ((int)(phv->phlevelsup) == context->sublevels_up && bms_equal(context->relids, phv->phrels)) return true; /* fall through to examine children */ } if (IsA(node, Query)) { /* Recurse into subselects */ bool result; context->sublevels_up++; result = query_tree_walker((Query *) node, (bool (*)())find_dependent_phvs_walker, (void *) context, 0); context->sublevels_up--; return result; } /* Shouldn't need to handle planner auxiliary nodes here */ Assert(!IsA(node, SpecialJoinInfo)); Assert(!IsA(node, AppendRelInfo)); Assert(!IsA(node, PlaceHolderInfo)); Assert(!IsA(node, MinMaxAggInfo)); return expression_tree_walker(node, (bool (*)())find_dependent_phvs_walker, (void *) context); } bool find_dependent_phvs(Node *node, int varno) { find_dependent_phvs_context context; context.relids = bms_make_singleton(varno); context.sublevels_up = 0; /* * Must be prepared to start with a Query or a bare expression tree. */ return query_or_expression_tree_walker(node, (bool (*)())find_dependent_phvs_walker, (void *) &context, 0); } /* * 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). * * 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; int sublevels_up; 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 ((int)phv->phlevelsup == context->sublevels_up && 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 */ } if (IsA(node, Query)) { /* Recurse into subselects */ bool result = false; context->sublevels_up++; result = query_tree_walker((Query*)node, (bool (*)())substitute_multiple_relids_walker, (void*)context, 0); context->sublevels_up--; return result; } /* Shouldn't need to handle planner auxiliary nodes here */ AssertEreport(!IsA(node, SpecialJoinInfo), MOD_OPT_REWRITE, "Shouldn't need to handle planner auxiliary node SpecialJoinInfo in substitute_multiple_relids_walker"); Assert(!IsA(node, LateralJoinInfo)); AssertEreport(!IsA(node, AppendRelInfo), MOD_OPT_REWRITE, "Shouldn't need to handle planner auxiliary node AppendRelInfo in substitute_multiple_relids_walker"); AssertEreport(!IsA(node, PlaceHolderInfo), MOD_OPT_REWRITE, "Shouldn't need to handle planner auxiliary node PlaceHolderInfo in substitute_multiple_relids_walker"); AssertEreport(!IsA(node, MinMaxAggInfo), MOD_OPT_REWRITE, "Shouldn't need to handle planner auxiliary node MinMaxAggInfo in substitute_multiple_relids_walker"); return expression_tree_walker(node, (bool (*)())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.sublevels_up = 0; context.subrelids = subrelids; /* * Must be prepared to start with a Query or a bare expression tree. */ (void)query_or_expression_tree_walker(node, (bool (*)())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 also need to apply substitute_multiple_relids to their * translated_vars lists, since those might contain PlaceHolderVars. * * 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 = NULL; 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 */ AssertEreport(appinfo->parent_relid != (uint)varno, MOD_OPT_REWRITE, "The parent_relid shouldn't ever be a pullup target in fix_append_rel_relids"); if (appinfo->child_relid == (uint)varno) { if (subvarno < 0) subvarno = bms_singleton_member(subrelids); appinfo->child_relid = subvarno; } /* Also finish fixups for its translated vars */ substitute_multiple_relids((Node*)appinfo->translated_vars, varno, subrelids); } } /* * 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; 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; ListCell* l = NULL; foreach (l, f->fromlist) { result = bms_join(result, get_relids_in_jointree((Node*)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); } else { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("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 = NULL; jtnode = find_jointree_node_for_rel((Node*)root->parse->jointree, joinrelid); if (jtnode == NULL) ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED), (errmsg("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) { 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; ListCell* l = NULL; foreach (l, f->fromlist) { jtnode = find_jointree_node_for_rel((Node*)lfirst(l), relid); if (jtnode != NULL) 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 != NULL) return jtnode; jtnode = find_jointree_node_for_rel(j->rarg, relid); if (jtnode != NULL) return jtnode; } else { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized node type: %d", (int)nodeTag(jtnode)))); } return NULL; } /* * We use this function to determine whether we should rewrite a 'full join on P' query to * a 'left join on P union all right anti full join on P'. * If we can find a condition to redistribute two relations, we will not rewrite, otherwise, we will. */ bool equalAndRedistributable(Node* quals) { bool ret = false; if (quals == NULL) return false; switch (nodeTag(quals)) { case T_OpExpr: { OpExpr* op = (OpExpr*)quals; if (list_length(op->args) != 2) /* 2 is the length of arguments to the operator. */ break; /* We only consider system operators. */ if (op->opno >= FirstNormalObjectId) break; char* opname = get_opname(op->opno); if (opname == NULL) break; /* If it is a '=' and all of its operators are redistributale, * no need to rewrite. */ if (strcmp(opname, "=") == 0) { ret = true; ListCell* lc = NULL; foreach (lc, op->args) { Node* node = (Node*)lfirst(lc); if (!IsTypeDistributable(exprType(node))) { ret = false; break; } } } pfree_ext(opname); break; } case T_List: { ListCell* lc = NULL; /* * If it is a List, all ListCells must be AND-ed, if we find a * qual that is '=' and redistributable, then return true; */ foreach (lc, (List*)quals) { bool tmp = equalAndRedistributable((Node*)lfirst(lc)); if (tmp) { ret = true; break; } } break; } case T_BoolExpr: { BoolExpr* op = (BoolExpr*)quals; ListCell* lc = NULL; /* * If it is a List, all ListCells must be AND-ed, if we find a * qual that is '=' and redistributable, then return true; * All other cases must rewrite. */ if (op->boolop == AND_EXPR) { foreach (lc, op->args) { bool tmp = equalAndRedistributable((Node*)lfirst(lc)); if (tmp) { ret = true; break; } } } break; } default: /* Default: rewrite */ ret = false; break; } return ret; } /* * After rewritting a 'full join on 1=1' to a 'left join union all right anti full join' query, * some operations can not be done on subqueries, so we reset them to NULL. * These operations will be done on the parent query. */ static void reset_operations_need_done_on_parent(Query* query) { AssertEreport(IsA(query, Query), MOD_OPT_REWRITE, "query mismatch in reset_operations_need_done_on_parent"); query->hasAggs = false; query->groupClause = NIL; query->groupingSets = NIL; query->sortClause = NIL; query->distinctClause = NIL; query->hasDistinctOn = NIL; query->limitCount = NULL; query->limitOffset = NULL; query->hasWindowFuncs = false; query->windowClause = NULL; query->havingQual = NULL; query->mergeTarget_relation = 0; query->mergeSourceTargetList = NIL; query->mergeActionList = NIL; } /* * reduce_inequality_fulljoins * Entry function to implement 'full join on 1=1' rewriting. We will call * reduce_inequality_fulljoins_jointree_recurse recursively to implement it. */ void reduce_inequality_fulljoins(PlannerInfo* root) { Node* jtnode = NULL; /* Begin recursion through the jointree */ jtnode = reduce_inequality_fulljoins_jointree_recurse(root, (Node*)root->parse->jointree); /* * 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); } /* * reduce_inequality_fulljoins_jointree_recurse * * Rewrite a 'full join' to 'left join union all right anti full join'. * * Consider this query: select * from t1 full join t2 on 1=1 * * In stand-alone system, all data of t1 and t2 are on a same node, we can use * merge join to process this query. But, in a distribute system, data of t1 and * t2 are redistributed on multiple servers, we can not use merge join directly. * If we move all data of t1 and t2 to the same node, this node maybe can not * hold it, especially on a cluster which processes large amount of data. * * This function will rewrite this query to (select *from t1 left join t2 on 1=1) * union all (select *from t1 right anti full join t2 on 1=1) NOTE: This query * is a user-friendly expression of the internal query tree,and users can not * send this query to GaussDB directly. * * We can only user Nestloop join method to execute this query, because there is * no join key. * * If a query like this: select * from t1 full join t2 on P, and no expressions * on P is distributable, we will rewrite the query also. For example, t1.floata * = t2.floata, floata's type is float, which is not redistributable. In this * example, we can use nestloop, hashjoin or mergejoin after rewritting and * broadcast one of the two tables. * * If we find a JoinExpr which meets the rewritting condition, we begin to rewrite. * We copy the original query twice, one of them expresses left join and the other * one expresses right anti full join. We use another query which called * partial_query to express union query. * * Some operations, such as limit, agg, etc., can not be execute on the two * subqueries copied from the original query, so we should reset this operation * nodes to empty. * * If multiple JoinExpr on the same layer(in the same fromlist), we process them * one by one in one recursive invocation. * * If multiple JoinExpr on different layers, we only process the top layer in * one recursive invocation, lower layers will be processesed in deeper recursive * invocations. */ static Node* reduce_inequality_fulljoins_jointree_recurse(PlannerInfo* root, Node* jtnode) { Assert(IS_STREAM_PLAN); if (jtnode == NULL || IsA(jtnode, RangeTblRef)) { return jtnode; /* jtnode is returned unmodified */ } else if (IsA(jtnode, FromExpr)) { FromExpr* f = (FromExpr*)jtnode; List* newfromlist = NIL; ListCell* l = NULL; foreach (l, f->fromlist) { Node* newchild = NULL; newchild = reduce_inequality_fulljoins_jointree_recurse(root, (Node*)lfirst(l)); newfromlist = lappend(newfromlist, newchild); } /* QUALS SHOULD BE HERE. Build the replacement FromExpr; */ jtnode = (Node*)makeFromExpr(newfromlist, (Node*)copyObject(f->quals)); } else if (IsA(jtnode, JoinExpr)) { JoinExpr* j = (JoinExpr*)jtnode; if (j->jointype == JOIN_FULL && !equalAndRedistributable(j->quals)) { Query* partial_query = makeNode(Query); Query* setop1 = (Query*)copyObject(root->parse); Query* setop2 = (Query*)copyObject(root->parse); setop1->is_from_full_join_rewrite = true; setop2->is_from_full_join_rewrite = true; JoinExpr* j1 = (JoinExpr*)copyObject(j); JoinExpr* j2 = (JoinExpr*)copyObject(j); RangeTblEntry* joinrte = (RangeTblEntry*)list_nth(root->parse->rtable, j->rtindex - 1); RangeTblEntry* joinrte1 = (RangeTblEntry*)list_nth(setop1->rtable, j->rtindex - 1); RangeTblEntry* joinrte2 = (RangeTblEntry*)list_nth(setop2->rtable, j->rtindex - 1); j1->jointype = JOIN_LEFT; j2->jointype = JOIN_RIGHT_ANTI_FULL; joinrte1->jointype = JOIN_LEFT; joinrte2->jointype = JOIN_RIGHT_ANTI_FULL; /* Because the two subqueries are pushed down for 2 layers, fix * vars' levelsup in qulas. */ IncrementVarSublevelsUp(j1->quals, 2, 1); IncrementVarSublevelsUp(j2->quals, 2, 1); /* No quals in FromExpr. Search 'QUALS SHOULD BE HERE.' in this * source code file. */ setop1->jointree = makeFromExpr(list_make1(j1), NULL); setop2->jointree = makeFromExpr(list_make1(j2), NULL); setop1->commandType = CMD_SELECT; setop2->commandType = CMD_SELECT; setop1->resultRelation = 0; setop2->resultRelation = 0; int resno = 1; ListCell* lc = NULL; List* targetList = NIL; List* colnames = joinrte->eref->colnames; /* * Make targetlist for two subqueries. * All vars in joinaliasvars should be added to the subquery's targetlist. */ foreach (lc, joinrte->joinaliasvars) { TargetEntry* te = NULL; Expr* expr = NULL; Node* node = (Node*)lfirst(lc); char* varname = strVal(list_nth(colnames, resno - 1)); switch (nodeTag(node)) { case T_Var: expr = (Expr*)makeVar(j->rtindex, resno, exprType(node), exprTypmod(node), exprCollation(node), 0); break; default: expr = (Expr*)copyObject(node); break; } te = makeTargetEntry((Expr*)expr, resno, varname, false); targetList = lappend(targetList, te); resno++; } setop1->targetList = targetList; setop2->targetList = targetList; /* * Reset some members to NULL, such as members related to agg, limit, * window function. We will do these operations in the parent query, * not in subqueries, so reset them to NULL. */ reset_operations_need_done_on_parent(setop1); reset_operations_need_done_on_parent(setop2); /* Create RTEs for partial_query */ RangeTblEntry* rte1 = addRangeTableEntryForSubquery(NULL, setop1, makeAlias("setop1", NIL), false, true); RangeTblEntry* rte2 = addRangeTableEntryForSubquery(NULL, setop2, makeAlias("setop2", NIL), false, true); partial_query->commandType = CMD_SELECT; partial_query->canSetTag = true; partial_query->rtable = list_make2(rte1, rte2); partial_query->jointree = makeFromExpr(NIL, NULL); partial_query->can_push = root->parse->can_push; /* Generate setop struct for partial_query */ SetOperationStmt* op = makeNode(SetOperationStmt); op->op = SETOP_UNION; op->all = true; RangeTblRef* rtr1 = makeNode(RangeTblRef); RangeTblRef* rtr2 = makeNode(RangeTblRef); rtr1->rtindex = 1; rtr2->rtindex = 2; op->larg = (Node*)rtr1; op->rarg = (Node*)rtr2; partial_query->setOperations = (Node*)op; int newVarNo = list_length(root->parse->rtable) + 1; List* old_tlist = NIL; List* new_tlist = NIL; AttrNumber iterator_attno = 1; /* 1. Create targetList for partial_query * 2. Create old_tlist and new_tlist which mapped old vars to new vars. * We will use these two lists to replace old vars in the parent query to new vars. */ foreach (lc, joinrte->joinaliasvars) { Node* node = (Node*)lfirst(lc); char* varname = strVal(list_nth(colnames, iterator_attno - 1)); /* For partial_query's targetList */ Var* pvar = makeVar(1, iterator_attno, exprType(node), exprTypmod(node), exprCollation(node), 0); TargetEntry* te = makeTargetEntry((Expr*)pvar, /* expr */ list_length(partial_query->targetList) + 1, /* resno */ varname, false); partial_query->targetList = lappend(partial_query->targetList, te); Node* oldvar = NULL; Node* newvar = NULL; /* Gernerate old vars */ switch (node->type) { case T_Var: { Var* var = (Var*)node; Index varno = var->varno; AttrNumber varattno = var->varattno; Node* retnode = get_real_rte_varno_attno_or_node(root->parse, &varno, &varattno); if (retnode == NULL) { oldvar = (Node*)makeVar( varno, varattno, exprType(node), exprTypmod(node), exprCollation(node), 0); } else { oldvar = (Node*)copyObject(retnode); } } break; default: oldvar = (Node*)copyObject(node); break; } /* New vars that will be used to replace old vars */ newvar = (Node*)makeVar(newVarNo, iterator_attno, exprType(node), exprTypmod(node), exprCollation(node), 0); old_tlist = lappend(old_tlist, oldvar); new_tlist = lappend(new_tlist, newvar); op->colTypes = lappend_oid(op->colTypes, exprType(node)); op->colTypmods = lappend_int(op->colTypmods, exprTypmod(node)); op->colCollations = lappend_oid(op->colCollations, exprCollation(node)); iterator_attno++; } /* Generate subquery rte and add it to the range tables */ RangeTblEntry* rte = addRangeTableEntryForSubquery(NULL, partial_query, makeAlias("subquery", NIL), false, true); root->parse->rtable = lappend(root->parse->rtable, rte); root->parse->targetList = (List*)replace_node_clause( (Node*)root->parse->targetList, (Node*)old_tlist, (Node*)new_tlist, RNC_RECURSE_AGGREF); root->parse->jointree = (FromExpr*)replace_node_clause( (Node*)root->parse->jointree, (Node*)old_tlist, (Node*)new_tlist, RNC_RECURSE_AGGREF); root->parse->havingQual = (Node*)replace_node_clause( (Node*)root->parse->havingQual, (Node*)old_tlist, (Node*)new_tlist, RNC_RECURSE_AGGREF); root->parse->mergeSourceTargetList = (List*)replace_node_clause( (Node*)root->parse->mergeSourceTargetList, (Node*)old_tlist, (Node*)new_tlist, RNC_RECURSE_AGGREF); root->parse->mergeActionList = (List*)replace_node_clause( (Node*)root->parse->mergeActionList, (Node*)old_tlist, (Node*)new_tlist, RNC_RECURSE_AGGREF); /* Use this simple RangeTblRef to replace the JoinExpr that represents full join */ RangeTblRef* rtr = makeNode(RangeTblRef); rtr->rtindex = newVarNo; jtnode = (Node*)rtr; } else { /* Recurse to process children and collect their relids */ j->larg = reduce_inequality_fulljoins_jointree_recurse(root, j->larg); j->rarg = reduce_inequality_fulljoins_jointree_recurse(root, j->rarg); } } else ereport(ERROR, ((errmodule(MOD_OPT), errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("unrecognized node type: %d", (int)nodeTag(jtnode))))); return jtnode; } extern bool find_rownum_in_quals(PlannerInfo *root) { if (root->parse == NULL) { return false; } if(root->hasRownumQual) { return true; } bool hasRownum = false; ListCell *qualcell = NULL; List *quallist = get_quals_lists((Node *)root->parse->jointree); foreach (qualcell, quallist) { Node *clause = (Node *)lfirst(qualcell); if (contain_rownum_walker(clause, NULL)) { hasRownum = true; break; } } if (quallist) { list_free(quallist); } return hasRownum; } bool ContainRownumQual(const Query *parse) { if (!IsA(parse->jointree, FromExpr)) { return false; } return contain_rownum_walker(((FromExpr *)parse->jointree)->quals, NULL); }