/*------------------------------------------------------------------------- * * subselect.c * Planning routines for subselects and parameters. * * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION * src/backend/optimizer/plan/subselect.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/htup_details.h" #include "catalog/pg_operator.h" #include "catalog/pg_type.h" #include "executor/executor.h" #include "miscadmin.h" #include "nodes/makefuncs.h" #include "nodes/nodeFuncs.h" #include "optimizer/clauses.h" #include "optimizer/cost.h" #include "optimizer/pathnode.h" #include "optimizer/planmain.h" #include "optimizer/planner.h" #include "optimizer/prep.h" #include "optimizer/subselect.h" #include "optimizer/var.h" #include "parser/parse_relation.h" #include "rewrite/rewriteManip.h" #include "utils/builtins.h" #include "utils/lsyscache.h" #include "utils/syscache.h" typedef struct convert_testexpr_context { PlannerInfo *root; List *subst_nodes; /* Nodes to substitute for Params */ } convert_testexpr_context; typedef struct process_sublinks_context { PlannerInfo *root; bool isTopQual; } process_sublinks_context; typedef struct finalize_primnode_context { PlannerInfo *root; Bitmapset *paramids; /* Non-local PARAM_EXEC paramids found */ } finalize_primnode_context; static Node *build_subplan(PlannerInfo *root, Plan *plan, PlannerInfo *subroot, List *plan_params, SubLinkType subLinkType, int subLinkId, Node *testexpr, bool adjust_testexpr, bool unknownEqFalse); static List *generate_subquery_params(PlannerInfo *root, List *tlist, List **paramIds); static List *generate_subquery_vars(PlannerInfo *root, List *tlist, Index varno); static Node *convert_testexpr(PlannerInfo *root, Node *testexpr, List *subst_nodes); static Node *convert_testexpr_mutator(Node *node, convert_testexpr_context *context); static bool subplan_is_hashable(Plan *plan); static bool testexpr_is_hashable(Node *testexpr); static bool hash_ok_operator(OpExpr *expr); static bool simplify_EXISTS_query(PlannerInfo *root, Query *query); static Query *convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect, Node **testexpr, List **paramIds); static Node *replace_correlation_vars_mutator(Node *node, PlannerInfo *root); static Node *process_sublinks_mutator(Node *node, process_sublinks_context *context); static Bitmapset *finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params, Bitmapset *scan_params); static bool finalize_primnode(Node *node, finalize_primnode_context *context); /* * Select a PARAM_EXEC number to identify the given Var as a parameter for * the current subquery, or for a nestloop's inner scan. * If the Var already has a param in the current context, return that one. */ static int assign_param_for_var(PlannerInfo *root, Var *var) { ListCell *ppl; PlannerParamItem *pitem; Index levelsup; /* Find the query level the Var belongs to */ for (levelsup = var->varlevelsup; levelsup > 0; levelsup--) root = root->parent_root; /* If there's already a matching PlannerParamItem there, just use it */ foreach(ppl, root->plan_params) { pitem = (PlannerParamItem *) lfirst(ppl); if (IsA(pitem->item, Var)) { Var *pvar = (Var *) pitem->item; /* * This comparison must match _equalVar(), except for ignoring * varlevelsup. Note that _equalVar() ignores the location. */ if (pvar->varno == var->varno && pvar->varattno == var->varattno && pvar->vartype == var->vartype && pvar->vartypmod == var->vartypmod && pvar->varcollid == var->varcollid && pvar->varnoold == var->varnoold && pvar->varoattno == var->varoattno) return pitem->paramId; } } /* Nope, so make a new one */ var = (Var *) copyObject(var); var->varlevelsup = 0; pitem = makeNode(PlannerParamItem); pitem->item = (Node *) var; pitem->paramId = root->glob->nParamExec++; root->plan_params = lappend(root->plan_params, pitem); return pitem->paramId; } /* * Generate a Param node to replace the given Var, * which is expected to have varlevelsup > 0 (ie, it is not local). */ static Param * replace_outer_var(PlannerInfo *root, Var *var) { Param *retval; int i; Assert(var->varlevelsup > 0 && var->varlevelsup < root->query_level); /* Find the Var in the appropriate plan_params, or add it if not present */ i = assign_param_for_var(root, var); retval = makeNode(Param); retval->paramkind = PARAM_EXEC; retval->paramid = i; retval->paramtype = var->vartype; retval->paramtypmod = var->vartypmod; retval->paramcollid = var->varcollid; retval->location = var->location; return retval; } /* * Generate a Param node to replace the given Var, which will be supplied * from an upper NestLoop join node. * * This is effectively the same as replace_outer_var, except that we expect * the Var to be local to the current query level. */ Param * assign_nestloop_param_var(PlannerInfo *root, Var *var) { Param *retval; int i; Assert(var->varlevelsup == 0); i = assign_param_for_var(root, var); retval = makeNode(Param); retval->paramkind = PARAM_EXEC; retval->paramid = i; retval->paramtype = var->vartype; retval->paramtypmod = var->vartypmod; retval->paramcollid = var->varcollid; retval->location = var->location; return retval; } /* * Select a PARAM_EXEC number to identify the given PlaceHolderVar as a * parameter for the current subquery, or for a nestloop's inner scan. * If the PHV already has a param in the current context, return that one. * * This is just like assign_param_for_var, except for PlaceHolderVars. */ static int assign_param_for_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv) { ListCell *ppl; PlannerParamItem *pitem; Index levelsup; /* Find the query level the PHV belongs to */ for (levelsup = phv->phlevelsup; levelsup > 0; levelsup--) root = root->parent_root; /* If there's already a matching PlannerParamItem there, just use it */ foreach(ppl, root->plan_params) { pitem = (PlannerParamItem *) lfirst(ppl); if (IsA(pitem->item, PlaceHolderVar)) { PlaceHolderVar *pphv = (PlaceHolderVar *) pitem->item; /* We assume comparing the PHIDs is sufficient */ if (pphv->phid == phv->phid) return pitem->paramId; } } /* Nope, so make a new one */ phv = (PlaceHolderVar *) copyObject(phv); if (phv->phlevelsup != 0) { IncrementVarSublevelsUp((Node *) phv, -((int) phv->phlevelsup), 0); Assert(phv->phlevelsup == 0); } pitem = makeNode(PlannerParamItem); pitem->item = (Node *) phv; pitem->paramId = root->glob->nParamExec++; root->plan_params = lappend(root->plan_params, pitem); return pitem->paramId; } /* * Generate a Param node to replace the given PlaceHolderVar, * which is expected to have phlevelsup > 0 (ie, it is not local). * * This is just like replace_outer_var, except for PlaceHolderVars. */ static Param * replace_outer_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv) { Param *retval; int i; Assert(phv->phlevelsup > 0 && phv->phlevelsup < root->query_level); /* Find the PHV in the appropriate plan_params, or add it if not present */ i = assign_param_for_placeholdervar(root, phv); retval = makeNode(Param); retval->paramkind = PARAM_EXEC; retval->paramid = i; retval->paramtype = exprType((Node *) phv->phexpr); retval->paramtypmod = exprTypmod((Node *) phv->phexpr); retval->paramcollid = exprCollation((Node *) phv->phexpr); retval->location = -1; return retval; } /* * Generate a Param node to replace the given PlaceHolderVar, which will be * supplied from an upper NestLoop join node. * * This is just like assign_nestloop_param_var, except for PlaceHolderVars. */ Param * assign_nestloop_param_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv) { Param *retval; int i; Assert(phv->phlevelsup == 0); i = assign_param_for_placeholdervar(root, phv); retval = makeNode(Param); retval->paramkind = PARAM_EXEC; retval->paramid = i; retval->paramtype = exprType((Node *) phv->phexpr); retval->paramtypmod = exprTypmod((Node *) phv->phexpr); retval->paramcollid = exprCollation((Node *) phv->phexpr); retval->location = -1; return retval; } /* * Generate a Param node to replace the given Aggref * which is expected to have agglevelsup > 0 (ie, it is not local). */ static Param * replace_outer_agg(PlannerInfo *root, Aggref *agg) { Param *retval; PlannerParamItem *pitem; Index levelsup; Assert(agg->agglevelsup > 0 && agg->agglevelsup < root->query_level); /* Find the query level the Aggref belongs to */ for (levelsup = agg->agglevelsup; levelsup > 0; levelsup--) root = root->parent_root; /* * It does not seem worthwhile to try to match duplicate outer aggs. Just * make a new slot every time. */ agg = (Aggref *) copyObject(agg); IncrementVarSublevelsUp((Node *) agg, -((int) agg->agglevelsup), 0); Assert(agg->agglevelsup == 0); pitem = makeNode(PlannerParamItem); pitem->item = (Node *) agg; pitem->paramId = root->glob->nParamExec++; root->plan_params = lappend(root->plan_params, pitem); retval = makeNode(Param); retval->paramkind = PARAM_EXEC; retval->paramid = pitem->paramId; retval->paramtype = agg->aggtype; retval->paramtypmod = -1; retval->paramcollid = agg->aggcollid; retval->location = agg->location; return retval; } /* * Generate a Param node to replace the given GroupingFunc expression which is * expected to have agglevelsup > 0 (ie, it is not local). */ static Param * replace_outer_grouping(PlannerInfo *root, GroupingFunc *grp) { Param *retval; PlannerParamItem *pitem; Index levelsup; Assert(grp->agglevelsup > 0 && grp->agglevelsup < root->query_level); /* Find the query level the GroupingFunc belongs to */ for (levelsup = grp->agglevelsup; levelsup > 0; levelsup--) root = root->parent_root; /* * It does not seem worthwhile to try to match duplicate outer aggs. Just * make a new slot every time. */ grp = (GroupingFunc *) copyObject(grp); IncrementVarSublevelsUp((Node *) grp, -((int) grp->agglevelsup), 0); Assert(grp->agglevelsup == 0); pitem = makeNode(PlannerParamItem); pitem->item = (Node *) grp; pitem->paramId = root->glob->nParamExec++; root->plan_params = lappend(root->plan_params, pitem); retval = makeNode(Param); retval->paramkind = PARAM_EXEC; retval->paramid = pitem->paramId; retval->paramtype = exprType((Node *) grp); retval->paramtypmod = -1; retval->paramcollid = InvalidOid; retval->location = grp->location; return retval; } /* * Generate a new Param node that will not conflict with any other. * * This is used to create Params representing subplan outputs. * We don't need to build a PlannerParamItem for such a Param, but we do * need to record the PARAM_EXEC slot number as being allocated. */ static Param * generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod, Oid paramcollation) { Param *retval; retval = makeNode(Param); retval->paramkind = PARAM_EXEC; retval->paramid = root->glob->nParamExec++; retval->paramtype = paramtype; retval->paramtypmod = paramtypmod; retval->paramcollid = paramcollation; retval->location = -1; return retval; } /* * Assign a (nonnegative) PARAM_EXEC ID for a special parameter (one that * is not actually used to carry a value at runtime). Such parameters are * used for special runtime signaling purposes, such as connecting a * recursive union node to its worktable scan node or forcing plan * re-evaluation within the EvalPlanQual mechanism. No actual Param node * exists with this ID, however. */ int SS_assign_special_param(PlannerInfo *root) { return root->glob->nParamExec++; } /* * Get the datatype/typmod/collation of the first column of the plan's output. * * This information is stored for ARRAY_SUBLINK execution and for * exprType()/exprTypmod()/exprCollation(), which have no way to get at the * plan associated with a SubPlan node. We really only need the info for * EXPR_SUBLINK and ARRAY_SUBLINK subplans, but for consistency we save it * always. */ static void get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod, Oid *colcollation) { /* In cases such as EXISTS, tlist might be empty; arbitrarily use VOID */ if (plan->targetlist) { TargetEntry *tent = (TargetEntry *) linitial(plan->targetlist); Assert(IsA(tent, TargetEntry)); if (!tent->resjunk) { *coltype = exprType((Node *) tent->expr); *coltypmod = exprTypmod((Node *) tent->expr); *colcollation = exprCollation((Node *) tent->expr); return; } } *coltype = VOIDOID; *coltypmod = -1; *colcollation = InvalidOid; } /* * Convert a SubLink (as created by the parser) into a SubPlan. * * We are given the SubLink's contained query, type, ID, and testexpr. We are * also told if this expression appears at top level of a WHERE/HAVING qual. * * Note: we assume that the testexpr has been AND/OR flattened (actually, * it's been through eval_const_expressions), but not converted to * implicit-AND form; and any SubLinks in it should already have been * converted to SubPlans. The subquery is as yet untouched, however. * * The result is whatever we need to substitute in place of the SubLink node * in the executable expression. If we're going to do the subplan as a * regular subplan, this will be the constructed SubPlan node. If we're going * to do the subplan as an InitPlan, the SubPlan node instead goes into * root->init_plans, and what we return here is an expression tree * representing the InitPlan's result: usually just a Param node representing * a single scalar result, but possibly a row comparison tree containing * multiple Param nodes, or for a MULTIEXPR subquery a simple NULL constant * (since the real output Params are elsewhere in the tree, and the MULTIEXPR * subquery itself is in a resjunk tlist entry whose value is uninteresting). */ static Node * make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType, int subLinkId, Node *testexpr, bool isTopQual) { Query *subquery; bool simple_exists = false; double tuple_fraction; Plan *plan; PlannerInfo *subroot; List *plan_params; Node *result; /* * Copy the source Query node. This is a quick and dirty kluge to resolve * the fact that the parser can generate trees with multiple links to the * same sub-Query node, but the planner wants to scribble on the Query. * Try to clean this up when we do querytree redesign... */ subquery = (Query *) copyObject(orig_subquery); /* * If it's an EXISTS subplan, we might be able to simplify it. */ if (subLinkType == EXISTS_SUBLINK) simple_exists = simplify_EXISTS_query(root, subquery); /* * For an EXISTS subplan, tell lower-level planner to expect that only the * first tuple will be retrieved. For ALL and ANY subplans, we will be * able to stop evaluating if the test condition fails or matches, so very * often not all the tuples will be retrieved; for lack of a better idea, * specify 50% retrieval. For EXPR, MULTIEXPR, and ROWCOMPARE subplans, * use default behavior (we're only expecting one row out, anyway). * * NOTE: if you change these numbers, also change cost_subplan() in * path/costsize.c. * * XXX If an ANY subplan is uncorrelated, build_subplan may decide to hash * its output. In that case it would've been better to specify full * retrieval. At present, however, we can only check hashability after * we've made the subplan :-(. (Determining whether it'll fit in work_mem * is the really hard part.) Therefore, we don't want to be too * optimistic about the percentage of tuples retrieved, for fear of * selecting a plan that's bad for the materialization case. */ if (subLinkType == EXISTS_SUBLINK) tuple_fraction = 1.0; /* just like a LIMIT 1 */ else if (subLinkType == ALL_SUBLINK || subLinkType == ANY_SUBLINK) tuple_fraction = 0.5; /* 50% */ else tuple_fraction = 0.0; /* default behavior */ /* plan_params should not be in use in current query level */ Assert(root->plan_params == NIL); /* * Generate the plan for the subquery. */ plan = subquery_planner(root->glob, subquery, root, false, tuple_fraction, &subroot); /* Isolate the params needed by this specific subplan */ plan_params = root->plan_params; root->plan_params = NIL; /* And convert to SubPlan or InitPlan format. */ result = build_subplan(root, plan, subroot, plan_params, subLinkType, subLinkId, testexpr, true, isTopQual); /* * If it's a correlated EXISTS with an unimportant targetlist, we might be * able to transform it to the equivalent of an IN and then implement it * by hashing. We don't have enough information yet to tell which way is * likely to be better (it depends on the expected number of executions of * the EXISTS qual, and we are much too early in planning the outer query * to be able to guess that). So we generate both plans, if possible, and * leave it to the executor to decide which to use. */ if (simple_exists && IsA(result, SubPlan)) { Node *newtestexpr; List *paramIds; /* Make a second copy of the original subquery */ subquery = (Query *) copyObject(orig_subquery); /* and re-simplify */ simple_exists = simplify_EXISTS_query(root, subquery); Assert(simple_exists); /* See if it can be converted to an ANY query */ subquery = convert_EXISTS_to_ANY(root, subquery, &newtestexpr, ¶mIds); if (subquery) { /* Generate the plan for the ANY subquery; we'll need all rows */ plan = subquery_planner(root->glob, subquery, root, false, 0.0, &subroot); /* Isolate the params needed by this specific subplan */ plan_params = root->plan_params; root->plan_params = NIL; /* Now we can check if it'll fit in work_mem */ if (subplan_is_hashable(plan)) { SubPlan *hashplan; AlternativeSubPlan *asplan; /* OK, convert to SubPlan format. */ hashplan = (SubPlan *) build_subplan(root, plan, subroot, plan_params, ANY_SUBLINK, 0, newtestexpr, false, true); /* Check we got what we expected */ Assert(IsA(hashplan, SubPlan)); Assert(hashplan->parParam == NIL); Assert(hashplan->useHashTable); /* build_subplan won't have filled in paramIds */ hashplan->paramIds = paramIds; /* Leave it to the executor to decide which plan to use */ asplan = makeNode(AlternativeSubPlan); asplan->subplans = list_make2(result, hashplan); result = (Node *) asplan; } } } return result; } /* * Build a SubPlan node given the raw inputs --- subroutine for make_subplan * * Returns either the SubPlan, or a replacement expression if we decide to * make it an InitPlan, as explained in the comments for make_subplan. */ static Node * build_subplan(PlannerInfo *root, Plan *plan, PlannerInfo *subroot, List *plan_params, SubLinkType subLinkType, int subLinkId, Node *testexpr, bool adjust_testexpr, bool unknownEqFalse) { Node *result; SubPlan *splan; bool isInitPlan; ListCell *lc; /* * Initialize the SubPlan node. Note plan_id, plan_name, and cost fields * are set further down. */ splan = makeNode(SubPlan); splan->subLinkType = subLinkType; splan->testexpr = NULL; splan->paramIds = NIL; get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod, &splan->firstColCollation); splan->useHashTable = false; splan->unknownEqFalse = unknownEqFalse; splan->setParam = NIL; splan->parParam = NIL; splan->args = NIL; /* * Make parParam and args lists of param IDs and expressions that current * query level will pass to this child plan. */ foreach(lc, plan_params) { PlannerParamItem *pitem = (PlannerParamItem *) lfirst(lc); Node *arg = pitem->item; /* * The Var, PlaceHolderVar, or Aggref has already been adjusted to * have the correct varlevelsup, phlevelsup, or agglevelsup. * * If it's a PlaceHolderVar or Aggref, its arguments might contain * SubLinks, which have not yet been processed (see the comments for * SS_replace_correlation_vars). Do that now. */ if (IsA(arg, PlaceHolderVar) || IsA(arg, Aggref)) arg = SS_process_sublinks(root, arg, false); splan->parParam = lappend_int(splan->parParam, pitem->paramId); splan->args = lappend(splan->args, arg); } /* * Un-correlated or undirect correlated plans of EXISTS, EXPR, ARRAY, * ROWCOMPARE, or MULTIEXPR types can be used as initPlans. For EXISTS, * EXPR, or ARRAY, we return a Param referring to the result of evaluating * the initPlan. For ROWCOMPARE, we must modify the testexpr tree to * contain PARAM_EXEC Params instead of the PARAM_SUBLINK Params emitted * by the parser, and then return that tree. For MULTIEXPR, we return a * null constant: the resjunk targetlist item containing the SubLink does * not need to return anything useful, since the referencing Params are * elsewhere. */ if (splan->parParam == NIL && subLinkType == EXISTS_SUBLINK) { Param *prm; Assert(testexpr == NULL); prm = generate_new_param(root, BOOLOID, -1, InvalidOid); splan->setParam = list_make1_int(prm->paramid); isInitPlan = true; result = (Node *) prm; } else if (splan->parParam == NIL && subLinkType == EXPR_SUBLINK) { TargetEntry *te = linitial(plan->targetlist); Param *prm; Assert(!te->resjunk); Assert(testexpr == NULL); prm = generate_new_param(root, exprType((Node *) te->expr), exprTypmod((Node *) te->expr), exprCollation((Node *) te->expr)); splan->setParam = list_make1_int(prm->paramid); isInitPlan = true; result = (Node *) prm; } else if (splan->parParam == NIL && subLinkType == ARRAY_SUBLINK) { TargetEntry *te = linitial(plan->targetlist); Oid arraytype; Param *prm; Assert(!te->resjunk); Assert(testexpr == NULL); arraytype = get_promoted_array_type(exprType((Node *) te->expr)); if (!OidIsValid(arraytype)) elog(ERROR, "could not find array type for datatype %s", format_type_be(exprType((Node *) te->expr))); prm = generate_new_param(root, arraytype, exprTypmod((Node *) te->expr), exprCollation((Node *) te->expr)); splan->setParam = list_make1_int(prm->paramid); isInitPlan = true; result = (Node *) prm; } else if (splan->parParam == NIL && subLinkType == ROWCOMPARE_SUBLINK) { /* Adjust the Params */ List *params; Assert(testexpr != NULL); params = generate_subquery_params(root, plan->targetlist, &splan->paramIds); result = convert_testexpr(root, testexpr, params); splan->setParam = list_copy(splan->paramIds); isInitPlan = true; /* * The executable expression is returned to become part of the outer * plan's expression tree; it is not kept in the initplan node. */ } else if (subLinkType == MULTIEXPR_SUBLINK) { /* * Whether it's an initplan or not, it needs to set a PARAM_EXEC Param * for each output column. */ List *params; Assert(testexpr == NULL); params = generate_subquery_params(root, plan->targetlist, &splan->setParam); /* * Save the list of replacement Params in the n'th cell of * root->multiexpr_params; setrefs.c will use it to replace * PARAM_MULTIEXPR Params. */ while (list_length(root->multiexpr_params) < subLinkId) root->multiexpr_params = lappend(root->multiexpr_params, NIL); lc = list_nth_cell(root->multiexpr_params, subLinkId - 1); Assert(lfirst(lc) == NIL); lfirst(lc) = params; /* It can be an initplan if there are no parParams. */ if (splan->parParam == NIL) { isInitPlan = true; result = (Node *) makeNullConst(RECORDOID, -1, InvalidOid); } else { isInitPlan = false; result = (Node *) splan; } } else { /* * Adjust the Params in the testexpr, unless caller said it's not * needed. */ if (testexpr && adjust_testexpr) { List *params; params = generate_subquery_params(root, plan->targetlist, &splan->paramIds); splan->testexpr = convert_testexpr(root, testexpr, params); } else splan->testexpr = testexpr; /* * We can't convert subplans of ALL_SUBLINK or ANY_SUBLINK types to * initPlans, even when they are uncorrelated or undirect correlated, * because we need to scan the output of the subplan for each outer * tuple. But if it's a not-direct-correlated IN (= ANY) test, we * might be able to use a hashtable to avoid comparing all the tuples. */ if (subLinkType == ANY_SUBLINK && splan->parParam == NIL && subplan_is_hashable(plan) && testexpr_is_hashable(splan->testexpr)) splan->useHashTable = true; /* * Otherwise, we have the option to tack a Material node onto the top * of the subplan, to reduce the cost of reading it repeatedly. This * is pointless for a direct-correlated subplan, since we'd have to * recompute its results each time anyway. For uncorrelated/undirect * correlated subplans, we add Material unless the subplan's top plan * node would materialize its output anyway. Also, if enable_material * is false, then the user does not want us to materialize anything * unnecessarily, so we don't. */ else if (splan->parParam == NIL && enable_material && !ExecMaterializesOutput(nodeTag(plan))) plan = materialize_finished_plan(plan); result = (Node *) splan; isInitPlan = false; } /* * Add the subplan and its PlannerInfo to the global lists. */ root->glob->subplans = lappend(root->glob->subplans, plan); root->glob->subroots = lappend(root->glob->subroots, subroot); splan->plan_id = list_length(root->glob->subplans); if (isInitPlan) root->init_plans = lappend(root->init_plans, splan); /* * A parameterless subplan (not initplan) should be prepared to handle * REWIND efficiently. If it has direct parameters then there's no point * since it'll be reset on each scan anyway; and if it's an initplan then * there's no point since it won't get re-run without parameter changes * anyway. The input of a hashed subplan doesn't need REWIND either. */ if (splan->parParam == NIL && !isInitPlan && !splan->useHashTable) root->glob->rewindPlanIDs = bms_add_member(root->glob->rewindPlanIDs, splan->plan_id); /* Label the subplan for EXPLAIN purposes */ splan->plan_name = palloc(32 + 12 * list_length(splan->setParam)); sprintf(splan->plan_name, "%s %d", isInitPlan ? "InitPlan" : "SubPlan", splan->plan_id); if (splan->setParam) { char *ptr = splan->plan_name + strlen(splan->plan_name); ptr += sprintf(ptr, " (returns "); foreach(lc, splan->setParam) { ptr += sprintf(ptr, "$%d%s", lfirst_int(lc), lnext(lc) ? "," : ")"); } } /* Lastly, fill in the cost estimates for use later */ cost_subplan(root, splan, plan); return result; } /* * generate_subquery_params: build a list of Params representing the output * columns of a sublink's sub-select, given the sub-select's targetlist. * * We also return an integer list of the paramids of the Params. */ static List * generate_subquery_params(PlannerInfo *root, List *tlist, List **paramIds) { List *result; List *ids; ListCell *lc; result = ids = NIL; foreach(lc, tlist) { TargetEntry *tent = (TargetEntry *) lfirst(lc); Param *param; if (tent->resjunk) continue; param = generate_new_param(root, exprType((Node *) tent->expr), exprTypmod((Node *) tent->expr), exprCollation((Node *) tent->expr)); result = lappend(result, param); ids = lappend_int(ids, param->paramid); } *paramIds = ids; return result; } /* * generate_subquery_vars: build a list of Vars representing the output * columns of a sublink's sub-select, given the sub-select's targetlist. * The Vars have the specified varno (RTE index). */ static List * generate_subquery_vars(PlannerInfo *root, List *tlist, Index varno) { List *result; ListCell *lc; result = NIL; foreach(lc, tlist) { TargetEntry *tent = (TargetEntry *) lfirst(lc); Var *var; if (tent->resjunk) continue; var = makeVarFromTargetEntry(varno, tent); result = lappend(result, var); } return result; } /* * convert_testexpr: convert the testexpr given by the parser into * actually executable form. This entails replacing PARAM_SUBLINK Params * with Params or Vars representing the results of the sub-select. The * nodes to be substituted are passed in as the List result from * generate_subquery_params or generate_subquery_vars. */ static Node * convert_testexpr(PlannerInfo *root, Node *testexpr, List *subst_nodes) { convert_testexpr_context context; context.root = root; context.subst_nodes = subst_nodes; return convert_testexpr_mutator(testexpr, &context); } static Node * convert_testexpr_mutator(Node *node, convert_testexpr_context *context) { if (node == NULL) return NULL; if (IsA(node, Param)) { Param *param = (Param *) node; if (param->paramkind == PARAM_SUBLINK) { if (param->paramid <= 0 || param->paramid > list_length(context->subst_nodes)) elog(ERROR, "unexpected PARAM_SUBLINK ID: %d", param->paramid); /* * We copy the list item to avoid having doubly-linked * substructure in the modified parse tree. This is probably * unnecessary when it's a Param, but be safe. */ return (Node *) copyObject(list_nth(context->subst_nodes, param->paramid - 1)); } } if (IsA(node, SubLink)) { /* * If we come across a nested SubLink, it is neither necessary nor * correct to recurse into it: any PARAM_SUBLINKs we might find inside * belong to the inner SubLink not the outer. So just return it as-is. * * This reasoning depends on the assumption that nothing will pull * subexpressions into or out of the testexpr field of a SubLink, at * least not without replacing PARAM_SUBLINKs first. If we did want * to do that we'd need to rethink the parser-output representation * altogether, since currently PARAM_SUBLINKs are only unique per * SubLink not globally across the query. The whole point of * replacing them with Vars or PARAM_EXEC nodes is to make them * globally unique before they escape from the SubLink's testexpr. * * Note: this can't happen when called during SS_process_sublinks, * because that recursively processes inner SubLinks first. It can * happen when called from convert_ANY_sublink_to_join, though. */ return node; } return expression_tree_mutator(node, convert_testexpr_mutator, (void *) context); } /* * subplan_is_hashable: can we implement an ANY subplan by hashing? */ static bool subplan_is_hashable(Plan *plan) { double subquery_size; /* * The estimated size of the subquery result must fit in work_mem. (Note: * we use heap tuple overhead here even though the tuples will actually be * stored as MinimalTuples; this provides some fudge factor for hashtable * overhead.) */ subquery_size = plan->plan_rows * (MAXALIGN(plan->plan_width) + MAXALIGN(SizeofHeapTupleHeader)); if (subquery_size > work_mem * 1024L) return false; return true; } /* * testexpr_is_hashable: is an ANY SubLink's test expression hashable? */ static bool testexpr_is_hashable(Node *testexpr) { /* * The testexpr must be a single OpExpr, or an AND-clause containing only * OpExprs. * * The combining operators must be hashable and strict. The need for * hashability is obvious, since we want to use hashing. Without * strictness, behavior in the presence of nulls is too unpredictable. We * actually must assume even more than plain strictness: they can't yield * NULL for non-null inputs, either (see nodeSubplan.c). However, hash * indexes and hash joins assume that too. */ if (testexpr && IsA(testexpr, OpExpr)) { if (hash_ok_operator((OpExpr *) testexpr)) return true; } else if (and_clause(testexpr)) { ListCell *l; foreach(l, ((BoolExpr *) testexpr)->args) { Node *andarg = (Node *) lfirst(l); if (!IsA(andarg, OpExpr)) return false; if (!hash_ok_operator((OpExpr *) andarg)) return false; } return true; } return false; } /* * Check expression is hashable + strict * * We could use op_hashjoinable() and op_strict(), but do it like this to * avoid a redundant cache lookup. */ static bool hash_ok_operator(OpExpr *expr) { Oid opid = expr->opno; /* quick out if not a binary operator */ if (list_length(expr->args) != 2) return false; if (opid == ARRAY_EQ_OP) { /* array_eq is strict, but must check input type to ensure hashable */ /* XXX record_eq will need same treatment when it becomes hashable */ Node *leftarg = linitial(expr->args); return op_hashjoinable(opid, exprType(leftarg)); } else { /* else must look up the operator properties */ HeapTuple tup; Form_pg_operator optup; tup = SearchSysCache1(OPEROID, ObjectIdGetDatum(opid)); if (!HeapTupleIsValid(tup)) elog(ERROR, "cache lookup failed for operator %u", opid); optup = (Form_pg_operator) GETSTRUCT(tup); if (!optup->oprcanhash || !func_strict(optup->oprcode)) { ReleaseSysCache(tup); return false; } ReleaseSysCache(tup); return true; } } /* * SS_process_ctes: process a query's WITH list * * We plan each interesting WITH item and convert it to an initplan. * A side effect is to fill in root->cte_plan_ids with a list that * parallels root->parse->cteList and provides the subplan ID for * each CTE's initplan. */ void SS_process_ctes(PlannerInfo *root) { ListCell *lc; Assert(root->cte_plan_ids == NIL); foreach(lc, root->parse->cteList) { CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc); CmdType cmdType = ((Query *) cte->ctequery)->commandType; Query *subquery; Plan *plan; PlannerInfo *subroot; SubPlan *splan; int paramid; /* * Ignore SELECT CTEs that are not actually referenced anywhere. */ if (cte->cterefcount == 0 && cmdType == CMD_SELECT) { /* Make a dummy entry in cte_plan_ids */ root->cte_plan_ids = lappend_int(root->cte_plan_ids, -1); continue; } /* * Copy the source Query node. Probably not necessary, but let's keep * this similar to make_subplan. */ subquery = (Query *) copyObject(cte->ctequery); /* plan_params should not be in use in current query level */ Assert(root->plan_params == NIL); /* * Generate the plan for the CTE query. Always plan for full * retrieval --- we don't have enough info to predict otherwise. */ plan = subquery_planner(root->glob, subquery, root, cte->cterecursive, 0.0, &subroot); /* * Since the current query level doesn't yet contain any RTEs, it * should not be possible for the CTE to have requested parameters of * this level. */ if (root->plan_params) elog(ERROR, "unexpected outer reference in CTE query"); /* * Make a SubPlan node for it. This is just enough unlike * build_subplan that we can't share code. * * Note plan_id, plan_name, and cost fields are set further down. */ splan = makeNode(SubPlan); splan->subLinkType = CTE_SUBLINK; splan->testexpr = NULL; splan->paramIds = NIL; get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod, &splan->firstColCollation); splan->useHashTable = false; splan->unknownEqFalse = false; splan->setParam = NIL; splan->parParam = NIL; splan->args = NIL; /* * The node can't have any inputs (since it's an initplan), so the * parParam and args lists remain empty. (It could contain references * to earlier CTEs' output param IDs, but CTE outputs are not * propagated via the args list.) */ /* * Assign a param ID to represent the CTE's output. No ordinary * "evaluation" of this param slot ever happens, but we use the param * ID for setParam/chgParam signaling just as if the CTE plan were * returning a simple scalar output. (Also, the executor abuses the * ParamExecData slot for this param ID for communication among * multiple CteScan nodes that might be scanning this CTE.) */ paramid = SS_assign_special_param(root); splan->setParam = list_make1_int(paramid); /* * Add the subplan and its PlannerInfo to the global lists. */ root->glob->subplans = lappend(root->glob->subplans, plan); root->glob->subroots = lappend(root->glob->subroots, subroot); splan->plan_id = list_length(root->glob->subplans); root->init_plans = lappend(root->init_plans, splan); root->cte_plan_ids = lappend_int(root->cte_plan_ids, splan->plan_id); /* Label the subplan for EXPLAIN purposes */ splan->plan_name = psprintf("CTE %s", cte->ctename); /* Lastly, fill in the cost estimates for use later */ cost_subplan(root, splan, plan); } } /* * convert_ANY_sublink_to_join: try to convert an ANY SubLink to a join * * The caller has found an ANY SubLink at the top level of one of the query's * qual clauses, but has not checked the properties of the SubLink further. * Decide whether it is appropriate to process this SubLink in join style. * If so, form a JoinExpr and return it. Return NULL if the SubLink cannot * be converted to a join. * * The only non-obvious input parameter is available_rels: this is the set * of query rels that can safely be referenced in the sublink expression. * (We must restrict this to avoid changing the semantics when a sublink * is present in an outer join's ON qual.) The conversion must fail if * the converted qual would reference any but these parent-query relids. * * On success, the returned JoinExpr has larg = NULL and rarg = the jointree * item representing the pulled-up subquery. The caller must set larg to * represent the relation(s) on the lefthand side of the new join, and insert * the JoinExpr into the upper query's jointree at an appropriate place * (typically, where the lefthand relation(s) had been). Note that the * passed-in SubLink must also be removed from its original position in the * query quals, since the quals of the returned JoinExpr replace it. * (Notionally, we replace the SubLink with a constant TRUE, then elide the * redundant constant from the qual.) * * On success, the caller is also responsible for recursively applying * pull_up_sublinks processing to the rarg and quals of the returned JoinExpr. * (On failure, there is no need to do anything, since pull_up_sublinks will * be applied when we recursively plan the sub-select.) * * Side effects of a successful conversion include adding the SubLink's * subselect to the query's rangetable, so that it can be referenced in * the JoinExpr's rarg. */ JoinExpr * convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink, Relids available_rels) { JoinExpr *result; Query *parse = root->parse; Query *subselect = (Query *) sublink->subselect; Relids upper_varnos; int rtindex; RangeTblEntry *rte; RangeTblRef *rtr; List *subquery_vars; Node *quals; ParseState *pstate; Assert(sublink->subLinkType == ANY_SUBLINK); /* * The sub-select must not refer to any Vars of the parent query. (Vars of * higher levels should be okay, though.) */ if (contain_vars_of_level((Node *) subselect, 1)) return NULL; /* * The test expression must contain some Vars of the parent query, else * it's not gonna be a join. (Note that it won't have Vars referring to * the subquery, rather Params.) */ upper_varnos = pull_varnos(sublink->testexpr); if (bms_is_empty(upper_varnos)) return NULL; /* * However, it can't refer to anything outside available_rels. */ if (!bms_is_subset(upper_varnos, available_rels)) return NULL; /* * The combining operators and left-hand expressions mustn't be volatile. */ if (contain_volatile_functions(sublink->testexpr)) return NULL; /* Create a dummy ParseState for addRangeTableEntryForSubquery */ pstate = make_parsestate(NULL); /* * Okay, pull up the sub-select into upper range table. * * We rely here on the assumption that the outer query has no references * to the inner (necessarily true, other than the Vars that we build * below). Therefore this is a lot easier than what pull_up_subqueries has * to go through. */ rte = addRangeTableEntryForSubquery(pstate, subselect, makeAlias("ANY_subquery", NIL), false, false); parse->rtable = lappend(parse->rtable, rte); rtindex = list_length(parse->rtable); /* * Form a RangeTblRef for the pulled-up sub-select. */ rtr = makeNode(RangeTblRef); rtr->rtindex = rtindex; /* * Build a list of Vars representing the subselect outputs. */ subquery_vars = generate_subquery_vars(root, subselect->targetList, rtindex); /* * Build the new join's qual expression, replacing Params with these Vars. */ quals = convert_testexpr(root, sublink->testexpr, subquery_vars); /* * And finally, build the JoinExpr node. */ result = makeNode(JoinExpr); result->jointype = JOIN_SEMI; result->isNatural = false; result->larg = NULL; /* caller must fill this in */ result->rarg = (Node *) rtr; result->usingClause = NIL; result->quals = quals; result->alias = NULL; result->rtindex = 0; /* we don't need an RTE for it */ return result; } /* * convert_EXISTS_sublink_to_join: try to convert an EXISTS SubLink to a join * * The API of this function is identical to convert_ANY_sublink_to_join's, * except that we also support the case where the caller has found NOT EXISTS, * so we need an additional input parameter "under_not". */ JoinExpr * convert_EXISTS_sublink_to_join(PlannerInfo *root, SubLink *sublink, bool under_not, Relids available_rels) { JoinExpr *result; Query *parse = root->parse; Query *subselect = (Query *) sublink->subselect; Node *whereClause; int rtoffset; int varno; Relids clause_varnos; Relids upper_varnos; Assert(sublink->subLinkType == EXISTS_SUBLINK); /* * Can't flatten if it contains WITH. (We could arrange to pull up the * WITH into the parent query's cteList, but that risks changing the * semantics, since a WITH ought to be executed once per associated query * call.) Note that convert_ANY_sublink_to_join doesn't have to reject * this case, since it just produces a subquery RTE that doesn't have to * get flattened into the parent query. */ if (subselect->cteList) return NULL; /* * Copy the subquery so we can modify it safely (see comments in * make_subplan). */ subselect = (Query *) copyObject(subselect); /* * See if the subquery can be simplified based on the knowledge that it's * being used in EXISTS(). If we aren't able to get rid of its * targetlist, we have to fail, because the pullup operation leaves us * with noplace to evaluate the targetlist. */ if (!simplify_EXISTS_query(root, subselect)) return NULL; /* * The subquery must have a nonempty jointree, else we won't have a join. */ if (subselect->jointree->fromlist == NIL) return NULL; /* * Separate out the WHERE clause. (We could theoretically also remove * top-level plain JOIN/ON clauses, but it's probably not worth the * trouble.) */ whereClause = subselect->jointree->quals; subselect->jointree->quals = NULL; /* * The rest of the sub-select must not refer to any Vars of the parent * query. (Vars of higher levels should be okay, though.) */ if (contain_vars_of_level((Node *) subselect, 1)) return NULL; /* * On the other hand, the WHERE clause must contain some Vars of the * parent query, else it's not gonna be a join. */ if (!contain_vars_of_level(whereClause, 1)) return NULL; /* * We don't risk optimizing if the WHERE clause is volatile, either. */ if (contain_volatile_functions(whereClause)) return NULL; /* * Prepare to pull up the sub-select into top range table. * * We rely here on the assumption that the outer query has no references * to the inner (necessarily true). Therefore this is a lot easier than * what pull_up_subqueries has to go through. * * In fact, it's even easier than what convert_ANY_sublink_to_join has to * do. The machinations of simplify_EXISTS_query ensured that there is * nothing interesting in the subquery except an rtable and jointree, and * even the jointree FromExpr no longer has quals. So we can just append * the rtable to our own and use the FromExpr in our jointree. But first, * adjust all level-zero varnos in the subquery to account for the rtable * merger. */ rtoffset = list_length(parse->rtable); OffsetVarNodes((Node *) subselect, rtoffset, 0); OffsetVarNodes(whereClause, rtoffset, 0); /* * Upper-level vars in subquery will now be one level closer to their * parent than before; in particular, anything that had been level 1 * becomes level zero. */ IncrementVarSublevelsUp((Node *) subselect, -1, 1); IncrementVarSublevelsUp(whereClause, -1, 1); /* * Now that the WHERE clause is adjusted to match the parent query * environment, we can easily identify all the level-zero rels it uses. * The ones <= rtoffset belong to the upper query; the ones > rtoffset do * not. */ clause_varnos = pull_varnos(whereClause); upper_varnos = NULL; while ((varno = bms_first_member(clause_varnos)) >= 0) { if (varno <= rtoffset) upper_varnos = bms_add_member(upper_varnos, varno); } bms_free(clause_varnos); Assert(!bms_is_empty(upper_varnos)); /* * Now that we've got the set of upper-level varnos, we can make the last * check: only available_rels can be referenced. */ if (!bms_is_subset(upper_varnos, available_rels)) return NULL; /* Now we can attach the modified subquery rtable to the parent */ parse->rtable = list_concat(parse->rtable, subselect->rtable); /* * And finally, build the JoinExpr node. */ result = makeNode(JoinExpr); result->jointype = under_not ? JOIN_ANTI : JOIN_SEMI; result->isNatural = false; result->larg = NULL; /* caller must fill this in */ /* flatten out the FromExpr node if it's useless */ if (list_length(subselect->jointree->fromlist) == 1) result->rarg = (Node *) linitial(subselect->jointree->fromlist); else result->rarg = (Node *) subselect->jointree; result->usingClause = NIL; result->quals = whereClause; result->alias = NULL; result->rtindex = 0; /* we don't need an RTE for it */ return result; } /* * simplify_EXISTS_query: remove any useless stuff in an EXISTS's subquery * * The only thing that matters about an EXISTS query is whether it returns * zero or more than zero rows. Therefore, we can remove certain SQL features * that won't affect that. The only part that is really likely to matter in * typical usage is simplifying the targetlist: it's a common habit to write * "SELECT * FROM" even though there is no need to evaluate any columns. * * Note: by suppressing the targetlist we could cause an observable behavioral * change, namely that any errors that might occur in evaluating the tlist * won't occur, nor will other side-effects of volatile functions. This seems * unlikely to bother anyone in practice. * * Returns TRUE if was able to discard the targetlist, else FALSE. */ static bool simplify_EXISTS_query(PlannerInfo *root, Query *query) { /* * We don't try to simplify at all if the query uses set operations, * aggregates, grouping sets, modifying CTEs, HAVING, OFFSET, or FOR * UPDATE/SHARE; none of these seem likely in normal usage and their * possible effects are complex. (Note: we could ignore an "OFFSET 0" * clause, but that traditionally is used as an optimization fence, so we * don't.) */ if (query->commandType != CMD_SELECT || query->setOperations || query->hasAggs || query->groupingSets || query->hasWindowFuncs || query->hasModifyingCTE || query->havingQual || query->limitOffset || query->rowMarks) return false; /* * LIMIT with a constant positive (or NULL) value doesn't affect the * semantics of EXISTS, so let's ignore such clauses. This is worth doing * because people accustomed to certain other DBMSes may be in the habit * of writing EXISTS(SELECT ... LIMIT 1) as an optimization. If there's a * LIMIT with anything else as argument, though, we can't simplify. */ if (query->limitCount) { /* * The LIMIT clause has not yet been through eval_const_expressions, * so we have to apply that here. It might seem like this is a waste * of cycles, since the only case plausibly worth worrying about is * "LIMIT 1" ... but what we'll actually see is "LIMIT int8(1::int4)", * so we have to fold constants or we're not going to recognize it. */ Node *node = eval_const_expressions(root, query->limitCount); Const *limit; /* Might as well update the query if we simplified the clause. */ query->limitCount = node; if (!IsA(node, Const)) return false; limit = (Const *) node; Assert(limit->consttype == INT8OID); if (!limit->constisnull && DatumGetInt64(limit->constvalue) <= 0) return false; /* Whether or not the targetlist is safe, we can drop the LIMIT. */ query->limitCount = NULL; } /* * Mustn't throw away the targetlist if it contains set-returning * functions; those could affect whether zero rows are returned! */ if (expression_returns_set((Node *) query->targetList)) return false; /* * Otherwise, we can throw away the targetlist, as well as any GROUP, * WINDOW, DISTINCT, and ORDER BY clauses; none of those clauses will * change a nonzero-rows result to zero rows or vice versa. (Furthermore, * since our parsetree representation of these clauses depends on the * targetlist, we'd better throw them away if we drop the targetlist.) */ query->targetList = NIL; query->groupClause = NIL; query->windowClause = NIL; query->distinctClause = NIL; query->sortClause = NIL; query->hasDistinctOn = false; return true; } /* * convert_EXISTS_to_ANY: try to convert EXISTS to a hashable ANY sublink * * The subselect is expected to be a fresh copy that we can munge up, * and to have been successfully passed through simplify_EXISTS_query. * * On success, the modified subselect is returned, and we store a suitable * upper-level test expression at *testexpr, plus a list of the subselect's * output Params at *paramIds. (The test expression is already Param-ified * and hence need not go through convert_testexpr, which is why we have to * deal with the Param IDs specially.) * * On failure, returns NULL. */ static Query * convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect, Node **testexpr, List **paramIds) { Node *whereClause; List *leftargs, *rightargs, *opids, *opcollations, *newWhere, *tlist, *testlist, *paramids; ListCell *lc, *rc, *oc, *cc; AttrNumber resno; /* * Query must not require a targetlist, since we have to insert a new one. * Caller should have dealt with the case already. */ Assert(subselect->targetList == NIL); /* * Separate out the WHERE clause. (We could theoretically also remove * top-level plain JOIN/ON clauses, but it's probably not worth the * trouble.) */ whereClause = subselect->jointree->quals; subselect->jointree->quals = NULL; /* * The rest of the sub-select must not refer to any Vars of the parent * query. (Vars of higher levels should be okay, though.) * * Note: we need not check for Aggrefs separately because we know the * sub-select is as yet unoptimized; any uplevel Aggref must therefore * contain an uplevel Var reference. This is not the case below ... */ if (contain_vars_of_level((Node *) subselect, 1)) return NULL; /* * We don't risk optimizing if the WHERE clause is volatile, either. */ if (contain_volatile_functions(whereClause)) return NULL; /* * Clean up the WHERE clause by doing const-simplification etc on it. * Aside from simplifying the processing we're about to do, this is * important for being able to pull chunks of the WHERE clause up into the * parent query. Since we are invoked partway through the parent's * preprocess_expression() work, earlier steps of preprocess_expression() * wouldn't get applied to the pulled-up stuff unless we do them here. For * the parts of the WHERE clause that get put back into the child query, * this work is partially duplicative, but it shouldn't hurt. * * Note: we do not run flatten_join_alias_vars. This is OK because any * parent aliases were flattened already, and we're not going to pull any * child Vars (of any description) into the parent. * * Note: passing the parent's root to eval_const_expressions is * technically wrong, but we can get away with it since only the * boundParams (if any) are used, and those would be the same in a * subroot. */ whereClause = eval_const_expressions(root, whereClause); whereClause = (Node *) canonicalize_qual((Expr *) whereClause); whereClause = (Node *) make_ands_implicit((Expr *) whereClause); /* * We now have a flattened implicit-AND list of clauses, which we try to * break apart into "outervar = innervar" hash clauses. Anything that * can't be broken apart just goes back into the newWhere list. Note that * we aren't trying hard yet to ensure that we have only outer or only * inner on each side; we'll check that if we get to the end. */ leftargs = rightargs = opids = opcollations = newWhere = NIL; foreach(lc, (List *) whereClause) { OpExpr *expr = (OpExpr *) lfirst(lc); if (IsA(expr, OpExpr) && hash_ok_operator(expr)) { Node *leftarg = (Node *) linitial(expr->args); Node *rightarg = (Node *) lsecond(expr->args); if (contain_vars_of_level(leftarg, 1)) { leftargs = lappend(leftargs, leftarg); rightargs = lappend(rightargs, rightarg); opids = lappend_oid(opids, expr->opno); opcollations = lappend_oid(opcollations, expr->inputcollid); continue; } if (contain_vars_of_level(rightarg, 1)) { /* * We must commute the clause to put the outer var on the * left, because the hashing code in nodeSubplan.c expects * that. This probably shouldn't ever fail, since hashable * operators ought to have commutators, but be paranoid. */ expr->opno = get_commutator(expr->opno); if (OidIsValid(expr->opno) && hash_ok_operator(expr)) { leftargs = lappend(leftargs, rightarg); rightargs = lappend(rightargs, leftarg); opids = lappend_oid(opids, expr->opno); opcollations = lappend_oid(opcollations, expr->inputcollid); continue; } /* If no commutator, no chance to optimize the WHERE clause */ return NULL; } } /* Couldn't handle it as a hash clause */ newWhere = lappend(newWhere, expr); } /* * If we didn't find anything we could convert, fail. */ if (leftargs == NIL) return NULL; /* * There mustn't be any parent Vars or Aggs in the stuff that we intend to * put back into the child query. Note: you might think we don't need to * check for Aggs separately, because an uplevel Agg must contain an * uplevel Var in its argument. But it is possible that the uplevel Var * got optimized away by eval_const_expressions. Consider * * SUM(CASE WHEN false THEN uplevelvar ELSE 0 END) */ if (contain_vars_of_level((Node *) newWhere, 1) || contain_vars_of_level((Node *) rightargs, 1)) return NULL; if (root->parse->hasAggs && (contain_aggs_of_level((Node *) newWhere, 1) || contain_aggs_of_level((Node *) rightargs, 1))) return NULL; /* * And there can't be any child Vars in the stuff we intend to pull up. * (Note: we'd need to check for child Aggs too, except we know the child * has no aggs at all because of simplify_EXISTS_query's check. The same * goes for window functions.) */ if (contain_vars_of_level((Node *) leftargs, 0)) return NULL; /* * Also reject sublinks in the stuff we intend to pull up. (It might be * possible to support this, but doesn't seem worth the complication.) */ if (contain_subplans((Node *) leftargs)) return NULL; /* * Okay, adjust the sublevelsup in the stuff we're pulling up. */ IncrementVarSublevelsUp((Node *) leftargs, -1, 1); /* * Put back any child-level-only WHERE clauses. */ if (newWhere) subselect->jointree->quals = (Node *) make_ands_explicit(newWhere); /* * Build a new targetlist for the child that emits the expressions we * need. Concurrently, build a testexpr for the parent using Params to * reference the child outputs. (Since we generate Params directly here, * there will be no need to convert the testexpr in build_subplan.) */ tlist = testlist = paramids = NIL; resno = 1; /* there's no "forfour" so we have to chase one of the lists manually */ cc = list_head(opcollations); forthree(lc, leftargs, rc, rightargs, oc, opids) { Node *leftarg = (Node *) lfirst(lc); Node *rightarg = (Node *) lfirst(rc); Oid opid = lfirst_oid(oc); Oid opcollation = lfirst_oid(cc); Param *param; cc = lnext(cc); param = generate_new_param(root, exprType(rightarg), exprTypmod(rightarg), exprCollation(rightarg)); tlist = lappend(tlist, makeTargetEntry((Expr *) rightarg, resno++, NULL, false)); testlist = lappend(testlist, make_opclause(opid, BOOLOID, false, (Expr *) leftarg, (Expr *) param, InvalidOid, opcollation)); paramids = lappend_int(paramids, param->paramid); } /* Put everything where it should go, and we're done */ subselect->targetList = tlist; *testexpr = (Node *) make_ands_explicit(testlist); *paramIds = paramids; return subselect; } /* * Replace correlation vars (uplevel vars) with Params. * * Uplevel PlaceHolderVars and aggregates are replaced, too. * * Note: it is critical that this runs immediately after SS_process_sublinks. * Since we do not recurse into the arguments of uplevel PHVs and aggregates, * they will get copied to the appropriate subplan args list in the parent * query with uplevel vars not replaced by Params, but only adjusted in level * (see replace_outer_placeholdervar and replace_outer_agg). That's exactly * what we want for the vars of the parent level --- but if a PHV's or * aggregate's argument contains any further-up variables, they have to be * replaced with Params in their turn. That will happen when the parent level * runs SS_replace_correlation_vars. Therefore it must do so after expanding * its sublinks to subplans. And we don't want any steps in between, else * those steps would never get applied to the argument expressions, either in * the parent or the child level. * * Another fairly tricky thing going on here is the handling of SubLinks in * the arguments of uplevel PHVs/aggregates. Those are not touched inside the * intermediate query level, either. Instead, SS_process_sublinks recurses on * them after copying the PHV or Aggref expression into the parent plan level * (this is actually taken care of in build_subplan). */ Node * SS_replace_correlation_vars(PlannerInfo *root, Node *expr) { /* No setup needed for tree walk, so away we go */ return replace_correlation_vars_mutator(expr, root); } static Node * replace_correlation_vars_mutator(Node *node, PlannerInfo *root) { if (node == NULL) return NULL; if (IsA(node, Var)) { if (((Var *) node)->varlevelsup > 0) return (Node *) replace_outer_var(root, (Var *) node); } if (IsA(node, PlaceHolderVar)) { if (((PlaceHolderVar *) node)->phlevelsup > 0) return (Node *) replace_outer_placeholdervar(root, (PlaceHolderVar *) node); } if (IsA(node, Aggref)) { if (((Aggref *) node)->agglevelsup > 0) return (Node *) replace_outer_agg(root, (Aggref *) node); } if (IsA(node, GroupingFunc)) { if (((GroupingFunc *) node)->agglevelsup > 0) return (Node *) replace_outer_grouping(root, (GroupingFunc *) node); } return expression_tree_mutator(node, replace_correlation_vars_mutator, (void *) root); } /* * Expand SubLinks to SubPlans in the given expression. * * The isQual argument tells whether or not this expression is a WHERE/HAVING * qualifier expression. If it is, any sublinks appearing at top level need * not distinguish FALSE from UNKNOWN return values. */ Node * SS_process_sublinks(PlannerInfo *root, Node *expr, bool isQual) { process_sublinks_context context; context.root = root; context.isTopQual = isQual; return process_sublinks_mutator(expr, &context); } static Node * process_sublinks_mutator(Node *node, process_sublinks_context *context) { process_sublinks_context locContext; locContext.root = context->root; if (node == NULL) return NULL; if (IsA(node, SubLink)) { SubLink *sublink = (SubLink *) node; Node *testexpr; /* * First, recursively process the lefthand-side expressions, if any. * They're not top-level anymore. */ locContext.isTopQual = false; testexpr = process_sublinks_mutator(sublink->testexpr, &locContext); /* * Now build the SubPlan node and make the expr to return. */ return make_subplan(context->root, (Query *) sublink->subselect, sublink->subLinkType, sublink->subLinkId, testexpr, context->isTopQual); } /* * Don't recurse into the arguments of an outer PHV or aggregate here. Any * SubLinks in the arguments have to be dealt with at the outer query * level; they'll be handled when build_subplan collects the PHV or Aggref * into the arguments to be passed down to the current subplan. */ if (IsA(node, PlaceHolderVar)) { if (((PlaceHolderVar *) node)->phlevelsup > 0) return node; } else if (IsA(node, Aggref)) { if (((Aggref *) node)->agglevelsup > 0) return node; } /* * We should never see a SubPlan expression in the input (since this is * the very routine that creates 'em to begin with). We shouldn't find * ourselves invoked directly on a Query, either. */ Assert(!IsA(node, SubPlan)); Assert(!IsA(node, AlternativeSubPlan)); Assert(!IsA(node, Query)); /* * Because make_subplan() could return an AND or OR clause, we have to * take steps to preserve AND/OR flatness of a qual. We assume the input * has been AND/OR flattened and so we need no recursion here. * * (Due to the coding here, we will not get called on the List subnodes of * an AND; and the input is *not* yet in implicit-AND format. So no check * is needed for a bare List.) * * Anywhere within the top-level AND/OR clause structure, we can tell * make_subplan() that NULL and FALSE are interchangeable. So isTopQual * propagates down in both cases. (Note that this is unlike the meaning * of "top level qual" used in most other places in Postgres.) */ if (and_clause(node)) { List *newargs = NIL; ListCell *l; /* Still at qual top-level */ locContext.isTopQual = context->isTopQual; foreach(l, ((BoolExpr *) node)->args) { Node *newarg; newarg = process_sublinks_mutator(lfirst(l), &locContext); if (and_clause(newarg)) newargs = list_concat(newargs, ((BoolExpr *) newarg)->args); else newargs = lappend(newargs, newarg); } return (Node *) make_andclause(newargs); } if (or_clause(node)) { List *newargs = NIL; ListCell *l; /* Still at qual top-level */ locContext.isTopQual = context->isTopQual; foreach(l, ((BoolExpr *) node)->args) { Node *newarg; newarg = process_sublinks_mutator(lfirst(l), &locContext); if (or_clause(newarg)) newargs = list_concat(newargs, ((BoolExpr *) newarg)->args); else newargs = lappend(newargs, newarg); } return (Node *) make_orclause(newargs); } /* * If we recurse down through anything other than an AND or OR node, we * are definitely not at top qual level anymore. */ locContext.isTopQual = false; return expression_tree_mutator(node, process_sublinks_mutator, (void *) &locContext); } /* * SS_identify_outer_params - identify the Params available from outer levels * * This must be run after SS_replace_correlation_vars and SS_process_sublinks * processing is complete in a given query level as well as all of its * descendant levels (which means it's most practical to do it at the end of * processing the query level). We compute the set of paramIds that outer * levels will make available to this level+descendants, and record it in * root->outer_params for use while computing extParam/allParam sets in final * plan cleanup. (We can't just compute it then, because the upper levels' * plan_params lists are transient and will be gone by then.) */ void SS_identify_outer_params(PlannerInfo *root) { Bitmapset *outer_params; PlannerInfo *proot; ListCell *l; /* * If no parameters have been assigned anywhere in the tree, we certainly * don't need to do anything here. */ if (root->glob->nParamExec == 0) return; /* * Scan all query levels above this one to see which parameters are due to * be available from them, either because lower query levels have * requested them (via plan_params) or because they will be available from * initPlans of those levels. */ outer_params = NULL; for (proot = root->parent_root; proot != NULL; proot = proot->parent_root) { /* Include ordinary Var/PHV/Aggref params */ foreach(l, proot->plan_params) { PlannerParamItem *pitem = (PlannerParamItem *) lfirst(l); outer_params = bms_add_member(outer_params, pitem->paramId); } /* Include any outputs of outer-level initPlans */ foreach(l, proot->init_plans) { SubPlan *initsubplan = (SubPlan *) lfirst(l); ListCell *l2; foreach(l2, initsubplan->setParam) { outer_params = bms_add_member(outer_params, lfirst_int(l2)); } } /* Include worktable ID, if a recursive query is being planned */ if (proot->wt_param_id >= 0) outer_params = bms_add_member(outer_params, proot->wt_param_id); } root->outer_params = outer_params; } /* * SS_attach_initplans - attach initplans to topmost plan node * * Attach any initplans created in the current query level to the topmost plan * node for the query level, and increment that node's cost to account for * them. (The initPlans could actually go in any node at or above where * they're referenced, but there seems no reason to put them any lower than * the topmost node for the query level.) */ void SS_attach_initplans(PlannerInfo *root, Plan *plan) { ListCell *lc; plan->initPlan = root->init_plans; foreach(lc, plan->initPlan) { SubPlan *initsubplan = (SubPlan *) lfirst(lc); Cost initplan_cost; /* * Assume each initPlan gets run once during top plan startup. This * is a conservative overestimate, since in fact an initPlan might be * executed later than plan startup, or even not at all. */ initplan_cost = initsubplan->startup_cost + initsubplan->per_call_cost; plan->startup_cost += initplan_cost; plan->total_cost += initplan_cost; } } /* * SS_finalize_plan - do final parameter processing for a completed Plan. * * This recursively computes the extParam and allParam sets for every Plan * node in the given plan tree. (Oh, and RangeTblFunction.funcparams too.) * * We assume that SS_finalize_plan has already been run on any initplans or * subplans the plan tree could reference. */ void SS_finalize_plan(PlannerInfo *root, Plan *plan) { /* No setup needed, just recurse through plan tree. */ (void) finalize_plan(root, plan, root->outer_params, NULL); } /* * Recursive processing of all nodes in the plan tree * * valid_params is the set of param IDs supplied by outer plan levels * that are valid to reference in this plan node or its children. * * scan_params is a set of param IDs to force scan plan nodes to reference. * This is for EvalPlanQual support, and is always NULL at the top of the * recursion. * * The return value is the computed allParam set for the given Plan node. * This is just an internal notational convenience. * * Do not scribble on caller's values of valid_params or scan_params! */ static Bitmapset * finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params, Bitmapset *scan_params) { finalize_primnode_context context; int locally_added_param; Bitmapset *nestloop_params; Bitmapset *initExtParam; Bitmapset *initSetParam; Bitmapset *child_params; ListCell *l; if (plan == NULL) return NULL; context.root = root; context.paramids = NULL; /* initialize set to empty */ locally_added_param = -1; /* there isn't one */ nestloop_params = NULL; /* there aren't any */ /* * Examine any initPlans to determine the set of external params they * reference and the set of output params they supply. (We assume * SS_finalize_plan was run on them already.) */ initExtParam = initSetParam = NULL; foreach(l, plan->initPlan) { SubPlan *initsubplan = (SubPlan *) lfirst(l); Plan *initplan = planner_subplan_get_plan(root, initsubplan); ListCell *l2; initExtParam = bms_add_members(initExtParam, initplan->extParam); foreach(l2, initsubplan->setParam) { initSetParam = bms_add_member(initSetParam, lfirst_int(l2)); } } /* Any setParams are validly referenceable in this node and children */ if (initSetParam) valid_params = bms_union(valid_params, initSetParam); /* * When we call finalize_primnode, context.paramids sets are automatically * merged together. But when recursing to self, we have to do it the hard * way. We want the paramids set to include params in subplans as well as * at this level. */ /* Find params in targetlist and qual */ finalize_primnode((Node *) plan->targetlist, &context); finalize_primnode((Node *) plan->qual, &context); /* Check additional node-type-specific fields */ switch (nodeTag(plan)) { case T_Result: finalize_primnode(((Result *) plan)->resconstantqual, &context); break; case T_SeqScan: context.paramids = bms_add_members(context.paramids, scan_params); break; case T_SampleScan: finalize_primnode((Node *) ((SampleScan *) plan)->tablesample, &context); context.paramids = bms_add_members(context.paramids, scan_params); break; case T_IndexScan: finalize_primnode((Node *) ((IndexScan *) plan)->indexqual, &context); finalize_primnode((Node *) ((IndexScan *) plan)->indexorderby, &context); /* * we need not look at indexqualorig, since it will have the same * param references as indexqual. Likewise, we can ignore * indexorderbyorig. */ context.paramids = bms_add_members(context.paramids, scan_params); break; case T_IndexOnlyScan: finalize_primnode((Node *) ((IndexOnlyScan *) plan)->indexqual, &context); finalize_primnode((Node *) ((IndexOnlyScan *) plan)->indexorderby, &context); /* * we need not look at indextlist, since it cannot contain Params. */ context.paramids = bms_add_members(context.paramids, scan_params); break; case T_BitmapIndexScan: finalize_primnode((Node *) ((BitmapIndexScan *) plan)->indexqual, &context); /* * we need not look at indexqualorig, since it will have the same * param references as indexqual. */ break; case T_BitmapHeapScan: finalize_primnode((Node *) ((BitmapHeapScan *) plan)->bitmapqualorig, &context); context.paramids = bms_add_members(context.paramids, scan_params); break; case T_TidScan: finalize_primnode((Node *) ((TidScan *) plan)->tidquals, &context); context.paramids = bms_add_members(context.paramids, scan_params); break; case T_SubqueryScan: { SubqueryScan *sscan = (SubqueryScan *) plan; RelOptInfo *rel; /* We must run SS_finalize_plan on the subquery */ rel = find_base_rel(root, sscan->scan.scanrelid); Assert(rel->subplan == sscan->subplan); SS_finalize_plan(rel->subroot, sscan->subplan); /* Now we can add its extParams to the parent's params */ context.paramids = bms_add_members(context.paramids, sscan->subplan->extParam); /* We need scan_params too, though */ context.paramids = bms_add_members(context.paramids, scan_params); } break; case T_FunctionScan: { FunctionScan *fscan = (FunctionScan *) plan; ListCell *lc; /* * Call finalize_primnode independently on each function * expression, so that we can record which params are * referenced in each, in order to decide which need * re-evaluating during rescan. */ foreach(lc, fscan->functions) { RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc); finalize_primnode_context funccontext; funccontext = context; funccontext.paramids = NULL; finalize_primnode(rtfunc->funcexpr, &funccontext); /* remember results for execution */ rtfunc->funcparams = funccontext.paramids; /* add the function's params to the overall set */ context.paramids = bms_add_members(context.paramids, funccontext.paramids); } context.paramids = bms_add_members(context.paramids, scan_params); } break; case T_ValuesScan: finalize_primnode((Node *) ((ValuesScan *) plan)->values_lists, &context); context.paramids = bms_add_members(context.paramids, scan_params); break; case T_CteScan: { /* * You might think we should add the node's cteParam to * paramids, but we shouldn't because that param is just a * linkage mechanism for multiple CteScan nodes for the same * CTE; it is never used for changed-param signaling. What we * have to do instead is to find the referenced CTE plan and * incorporate its external paramids, so that the correct * things will happen if the CTE references outer-level * variables. See test cases for bug #4902. (We assume * SS_finalize_plan was run on the CTE plan already.) */ int plan_id = ((CteScan *) plan)->ctePlanId; Plan *cteplan; /* so, do this ... */ if (plan_id < 1 || plan_id > list_length(root->glob->subplans)) elog(ERROR, "could not find plan for CteScan referencing plan ID %d", plan_id); cteplan = (Plan *) list_nth(root->glob->subplans, plan_id - 1); context.paramids = bms_add_members(context.paramids, cteplan->extParam); #ifdef NOT_USED /* ... but not this */ context.paramids = bms_add_member(context.paramids, ((CteScan *) plan)->cteParam); #endif context.paramids = bms_add_members(context.paramids, scan_params); } break; case T_WorkTableScan: context.paramids = bms_add_member(context.paramids, ((WorkTableScan *) plan)->wtParam); context.paramids = bms_add_members(context.paramids, scan_params); break; case T_ForeignScan: finalize_primnode((Node *) ((ForeignScan *) plan)->fdw_exprs, &context); /* We assume fdw_scan_tlist cannot contain Params */ context.paramids = bms_add_members(context.paramids, scan_params); break; case T_CustomScan: { CustomScan *cscan = (CustomScan *) plan; ListCell *lc; finalize_primnode((Node *) cscan->custom_exprs, &context); /* We assume custom_scan_tlist cannot contain Params */ context.paramids = bms_add_members(context.paramids, scan_params); /* child nodes if any */ foreach(lc, cscan->custom_plans) { context.paramids = bms_add_members(context.paramids, finalize_plan(root, (Plan *) lfirst(lc), valid_params, scan_params)); } } break; case T_ModifyTable: { ModifyTable *mtplan = (ModifyTable *) plan; ListCell *l; /* Force descendant scan nodes to reference epqParam */ locally_added_param = mtplan->epqParam; valid_params = bms_add_member(bms_copy(valid_params), locally_added_param); scan_params = bms_add_member(bms_copy(scan_params), locally_added_param); finalize_primnode((Node *) mtplan->returningLists, &context); finalize_primnode((Node *) mtplan->onConflictSet, &context); finalize_primnode((Node *) mtplan->onConflictWhere, &context); foreach(l, mtplan->plans) { context.paramids = bms_add_members(context.paramids, finalize_plan(root, (Plan *) lfirst(l), valid_params, scan_params)); } } break; case T_Append: { ListCell *l; foreach(l, ((Append *) plan)->appendplans) { context.paramids = bms_add_members(context.paramids, finalize_plan(root, (Plan *) lfirst(l), valid_params, scan_params)); } } break; case T_MergeAppend: { ListCell *l; foreach(l, ((MergeAppend *) plan)->mergeplans) { context.paramids = bms_add_members(context.paramids, finalize_plan(root, (Plan *) lfirst(l), valid_params, scan_params)); } } break; case T_BitmapAnd: { ListCell *l; foreach(l, ((BitmapAnd *) plan)->bitmapplans) { context.paramids = bms_add_members(context.paramids, finalize_plan(root, (Plan *) lfirst(l), valid_params, scan_params)); } } break; case T_BitmapOr: { ListCell *l; foreach(l, ((BitmapOr *) plan)->bitmapplans) { context.paramids = bms_add_members(context.paramids, finalize_plan(root, (Plan *) lfirst(l), valid_params, scan_params)); } } break; case T_NestLoop: { ListCell *l; finalize_primnode((Node *) ((Join *) plan)->joinqual, &context); /* collect set of params that will be passed to right child */ foreach(l, ((NestLoop *) plan)->nestParams) { NestLoopParam *nlp = (NestLoopParam *) lfirst(l); nestloop_params = bms_add_member(nestloop_params, nlp->paramno); } } break; case T_MergeJoin: finalize_primnode((Node *) ((Join *) plan)->joinqual, &context); finalize_primnode((Node *) ((MergeJoin *) plan)->mergeclauses, &context); break; case T_HashJoin: finalize_primnode((Node *) ((Join *) plan)->joinqual, &context); finalize_primnode((Node *) ((HashJoin *) plan)->hashclauses, &context); break; case T_Limit: finalize_primnode(((Limit *) plan)->limitOffset, &context); finalize_primnode(((Limit *) plan)->limitCount, &context); break; case T_RecursiveUnion: /* child nodes are allowed to reference wtParam */ locally_added_param = ((RecursiveUnion *) plan)->wtParam; valid_params = bms_add_member(bms_copy(valid_params), locally_added_param); /* wtParam does *not* get added to scan_params */ break; case T_LockRows: /* Force descendant scan nodes to reference epqParam */ locally_added_param = ((LockRows *) plan)->epqParam; valid_params = bms_add_member(bms_copy(valid_params), locally_added_param); scan_params = bms_add_member(bms_copy(scan_params), locally_added_param); break; case T_WindowAgg: finalize_primnode(((WindowAgg *) plan)->startOffset, &context); finalize_primnode(((WindowAgg *) plan)->endOffset, &context); break; case T_Hash: case T_Agg: case T_Material: case T_Sort: case T_Unique: case T_Gather: case T_SetOp: case T_Group: break; default: elog(ERROR, "unrecognized node type: %d", (int) nodeTag(plan)); } /* Process left and right child plans, if any */ child_params = finalize_plan(root, plan->lefttree, valid_params, scan_params); context.paramids = bms_add_members(context.paramids, child_params); if (nestloop_params) { /* right child can reference nestloop_params as well as valid_params */ child_params = finalize_plan(root, plan->righttree, bms_union(nestloop_params, valid_params), scan_params); /* ... and they don't count as parameters used at my level */ child_params = bms_difference(child_params, nestloop_params); bms_free(nestloop_params); } else { /* easy case */ child_params = finalize_plan(root, plan->righttree, valid_params, scan_params); } context.paramids = bms_add_members(context.paramids, child_params); /* * Any locally generated parameter doesn't count towards its generating * plan node's external dependencies. (Note: if we changed valid_params * and/or scan_params, we leak those bitmapsets; not worth the notational * trouble to clean them up.) */ if (locally_added_param >= 0) { context.paramids = bms_del_member(context.paramids, locally_added_param); } /* Now we have all the paramids referenced in this node and children */ if (!bms_is_subset(context.paramids, valid_params)) elog(ERROR, "plan should not reference subplan's variable"); /* * The plan node's allParam and extParam fields should include all its * referenced paramids, plus contributions from any child initPlans. * However, any setParams of the initPlans should not be present in the * parent node's extParams, only in its allParams. (It's possible that * some initPlans have extParams that are setParams of other initPlans.) */ /* allParam must include initplans' extParams and setParams */ plan->allParam = bms_union(context.paramids, initExtParam); plan->allParam = bms_add_members(plan->allParam, initSetParam); /* extParam must include any initplan extParams */ plan->extParam = bms_union(context.paramids, initExtParam); /* but not any initplan setParams */ plan->extParam = bms_del_members(plan->extParam, initSetParam); /* * For speed at execution time, make sure extParam/allParam are actually * NULL if they are empty sets. */ if (bms_is_empty(plan->extParam)) plan->extParam = NULL; if (bms_is_empty(plan->allParam)) plan->allParam = NULL; return plan->allParam; } /* * finalize_primnode: add IDs of all PARAM_EXEC params appearing in the given * expression tree to the result set. */ static bool finalize_primnode(Node *node, finalize_primnode_context *context) { if (node == NULL) return false; if (IsA(node, Param)) { if (((Param *) node)->paramkind == PARAM_EXEC) { int paramid = ((Param *) node)->paramid; context->paramids = bms_add_member(context->paramids, paramid); } return false; /* no more to do here */ } if (IsA(node, SubPlan)) { SubPlan *subplan = (SubPlan *) node; Plan *plan = planner_subplan_get_plan(context->root, subplan); ListCell *lc; Bitmapset *subparamids; /* Recurse into the testexpr, but not into the Plan */ finalize_primnode(subplan->testexpr, context); /* * Remove any param IDs of output parameters of the subplan that were * referenced in the testexpr. These are not interesting for * parameter change signaling since we always re-evaluate the subplan. * Note that this wouldn't work too well if there might be uses of the * same param IDs elsewhere in the plan, but that can't happen because * generate_new_param never tries to merge params. */ foreach(lc, subplan->paramIds) { context->paramids = bms_del_member(context->paramids, lfirst_int(lc)); } /* Also examine args list */ finalize_primnode((Node *) subplan->args, context); /* * Add params needed by the subplan to paramids, but excluding those * we will pass down to it. (We assume SS_finalize_plan was run on * the subplan already.) */ subparamids = bms_copy(plan->extParam); foreach(lc, subplan->parParam) { subparamids = bms_del_member(subparamids, lfirst_int(lc)); } context->paramids = bms_join(context->paramids, subparamids); return false; /* no more to do here */ } return expression_tree_walker(node, finalize_primnode, (void *) context); } /* * SS_make_initplan_from_plan - given a plan tree, make it an InitPlan * * The plan is expected to return a scalar value of the given type/collation. * We build an EXPR_SUBLINK SubPlan node and put it into the initplan * list for the outer query level. A Param that represents the initplan's * output is returned. */ Param * SS_make_initplan_from_plan(PlannerInfo *root, PlannerInfo *subroot, Plan *plan, Oid resulttype, int32 resulttypmod, Oid resultcollation) { SubPlan *node; Param *prm; /* * Add the subplan and its PlannerInfo to the global lists. */ root->glob->subplans = lappend(root->glob->subplans, plan); root->glob->subroots = lappend(root->glob->subroots, subroot); /* * Create a SubPlan node and add it to the outer list of InitPlans. Note * it has to appear after any other InitPlans it might depend on (see * comments in ExecReScan). */ node = makeNode(SubPlan); node->subLinkType = EXPR_SUBLINK; get_first_col_type(plan, &node->firstColType, &node->firstColTypmod, &node->firstColCollation); node->plan_id = list_length(root->glob->subplans); root->init_plans = lappend(root->init_plans, node); /* * The node can't have any inputs (since it's an initplan), so the * parParam and args lists remain empty. */ cost_subplan(subroot, node, plan); /* * Make a Param that will be the subplan's output. */ prm = generate_new_param(root, resulttype, resulttypmod, resultcollation); node->setParam = list_make1_int(prm->paramid); /* Label the subplan for EXPLAIN purposes */ node->plan_name = psprintf("InitPlan %d (returns $%d)", node->plan_id, prm->paramid); return prm; }