1
/*-------------------------------------------------------------------------
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* Planning routines for subselects and parameters.
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* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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* src/backend/optimizer/plan/subselect.c
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*-------------------------------------------------------------------------
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#include "catalog/pg_operator.h"
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#include "catalog/pg_type.h"
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#include "executor/executor.h"
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#include "miscadmin.h"
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#include "nodes/makefuncs.h"
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#include "nodes/nodeFuncs.h"
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#include "optimizer/clauses.h"
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#include "optimizer/cost.h"
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#include "optimizer/planmain.h"
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#include "optimizer/planner.h"
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#include "optimizer/prep.h"
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#include "optimizer/subselect.h"
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#include "optimizer/var.h"
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#include "parser/parse_relation.h"
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#include "parser/parsetree.h"
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#include "rewrite/rewriteManip.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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#include "utils/syscache.h"
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typedef struct convert_testexpr_context
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List *subst_nodes; /* Nodes to substitute for Params */
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} convert_testexpr_context;
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typedef struct process_sublinks_context
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} process_sublinks_context;
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typedef struct finalize_primnode_context
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Bitmapset *paramids; /* Non-local PARAM_EXEC paramids found */
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} finalize_primnode_context;
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static Node *build_subplan(PlannerInfo *root, Plan *plan,
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List *rtable, List *rowmarks,
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SubLinkType subLinkType, Node *testexpr,
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bool adjust_testexpr, bool unknownEqFalse);
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static List *generate_subquery_params(PlannerInfo *root, List *tlist,
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static List *generate_subquery_vars(PlannerInfo *root, List *tlist,
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static Node *convert_testexpr(PlannerInfo *root,
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static Node *convert_testexpr_mutator(Node *node,
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convert_testexpr_context *context);
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static bool subplan_is_hashable(Plan *plan);
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static bool testexpr_is_hashable(Node *testexpr);
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static bool hash_ok_operator(OpExpr *expr);
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static bool simplify_EXISTS_query(Query *query);
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static Query *convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect,
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Node **testexpr, List **paramIds);
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static Node *replace_correlation_vars_mutator(Node *node, PlannerInfo *root);
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static Node *process_sublinks_mutator(Node *node,
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process_sublinks_context *context);
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static Bitmapset *finalize_plan(PlannerInfo *root,
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Bitmapset *valid_params,
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Bitmapset *scan_params);
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static bool finalize_primnode(Node *node, finalize_primnode_context *context);
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* Select a PARAM_EXEC number to identify the given Var.
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* If the Var already has a param slot, return that one.
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assign_param_for_var(PlannerInfo *root, Var *var)
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PlannerParamItem *pitem;
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abslevel = root->query_level - var->varlevelsup;
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/* If there's already a paramlist entry for this same Var, just use it */
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foreach(ppl, root->glob->paramlist)
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pitem = (PlannerParamItem *) lfirst(ppl);
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if (pitem->abslevel == abslevel && IsA(pitem->item, Var))
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Var *pvar = (Var *) pitem->item;
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if (pvar->varno == var->varno &&
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pvar->varattno == var->varattno &&
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pvar->vartype == var->vartype &&
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pvar->vartypmod == var->vartypmod)
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/* Nope, so make a new one */
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var = (Var *) copyObject(var);
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var->varlevelsup = 0;
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pitem = makeNode(PlannerParamItem);
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pitem->item = (Node *) var;
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pitem->abslevel = abslevel;
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root->glob->paramlist = lappend(root->glob->paramlist, pitem);
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/* i is already the correct list index for the new item */
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* Generate a Param node to replace the given Var,
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* which is expected to have varlevelsup > 0 (ie, it is not local).
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replace_outer_var(PlannerInfo *root, Var *var)
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Assert(var->varlevelsup > 0 && var->varlevelsup < root->query_level);
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* Find the Var in root->glob->paramlist, or add it if not present.
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* NOTE: in sufficiently complex querytrees, it is possible for the same
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* varno/abslevel to refer to different RTEs in different parts of the
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* parsetree, so that different fields might end up sharing the same Param
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* number. As long as we check the vartype/typmod as well, I believe that
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* this sort of aliasing will cause no trouble. The correct field should
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* get stored into the Param slot at execution in each part of the tree.
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i = assign_param_for_var(root, var);
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retval = makeNode(Param);
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retval->paramkind = PARAM_EXEC;
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retval->paramtype = var->vartype;
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retval->paramtypmod = var->vartypmod;
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retval->paramcollid = var->varcollid;
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retval->location = -1;
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* Generate a Param node to replace the given Var, which will be supplied
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* from an upper NestLoop join node.
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* Because we allow nestloop and subquery Params to alias each other,
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* this is effectively the same as replace_outer_var, except that we expect
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* the Var to be local to the current query level.
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assign_nestloop_param(PlannerInfo *root, Var *var)
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Assert(var->varlevelsup == 0);
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i = assign_param_for_var(root, var);
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retval = makeNode(Param);
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retval->paramkind = PARAM_EXEC;
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retval->paramtype = var->vartype;
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retval->paramtypmod = var->vartypmod;
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retval->paramcollid = var->varcollid;
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retval->location = -1;
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* Generate a Param node to replace the given Aggref
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* which is expected to have agglevelsup > 0 (ie, it is not local).
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replace_outer_agg(PlannerInfo *root, Aggref *agg)
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PlannerParamItem *pitem;
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Assert(agg->agglevelsup > 0 && agg->agglevelsup < root->query_level);
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abslevel = root->query_level - agg->agglevelsup;
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* It does not seem worthwhile to try to match duplicate outer aggs. Just
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* make a new slot every time.
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agg = (Aggref *) copyObject(agg);
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IncrementVarSublevelsUp((Node *) agg, -((int) agg->agglevelsup), 0);
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Assert(agg->agglevelsup == 0);
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pitem = makeNode(PlannerParamItem);
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pitem->item = (Node *) agg;
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pitem->abslevel = abslevel;
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root->glob->paramlist = lappend(root->glob->paramlist, pitem);
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i = list_length(root->glob->paramlist) - 1;
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retval = makeNode(Param);
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retval->paramkind = PARAM_EXEC;
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retval->paramtype = agg->aggtype;
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retval->paramtypmod = -1;
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retval->paramcollid = agg->aggcollid;
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retval->location = -1;
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* Generate a new Param node that will not conflict with any other.
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* This is used to allocate PARAM_EXEC slots for subplan outputs.
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generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod,
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PlannerParamItem *pitem;
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retval = makeNode(Param);
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retval->paramkind = PARAM_EXEC;
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retval->paramid = list_length(root->glob->paramlist);
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retval->paramtype = paramtype;
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retval->paramtypmod = paramtypmod;
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retval->paramcollid = paramcollation;
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retval->location = -1;
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pitem = makeNode(PlannerParamItem);
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pitem->item = (Node *) retval;
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pitem->abslevel = root->query_level;
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root->glob->paramlist = lappend(root->glob->paramlist, pitem);
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* Assign a (nonnegative) PARAM_EXEC ID for a special parameter (one that
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* is not actually used to carry a value at runtime). Such parameters are
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* used for special runtime signaling purposes, such as connecting a
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* recursive union node to its worktable scan node or forcing plan
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* re-evaluation within the EvalPlanQual mechanism.
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SS_assign_special_param(PlannerInfo *root)
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/* We generate a Param of datatype INTERNAL */
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param = generate_new_param(root, INTERNALOID, -1, InvalidOid);
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/* ... but the caller only cares about its ID */
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return param->paramid;
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* Get the datatype/typmod/collation of the first column of the plan's output.
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* This information is stored for ARRAY_SUBLINK execution and for
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* exprType()/exprTypmod()/exprCollation(), which have no way to get at the
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* plan associated with a SubPlan node. We really only need the info for
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* EXPR_SUBLINK and ARRAY_SUBLINK subplans, but for consistency we save it
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get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod,
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/* In cases such as EXISTS, tlist might be empty; arbitrarily use VOID */
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if (plan->targetlist)
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TargetEntry *tent = (TargetEntry *) linitial(plan->targetlist);
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Assert(IsA(tent, TargetEntry));
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*coltype = exprType((Node *) tent->expr);
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*coltypmod = exprTypmod((Node *) tent->expr);
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*colcollation = exprCollation((Node *) tent->expr);
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*colcollation = InvalidOid;
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* Convert a SubLink (as created by the parser) into a SubPlan.
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* We are given the SubLink's contained query, type, and testexpr. We are
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* also told if this expression appears at top level of a WHERE/HAVING qual.
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* Note: we assume that the testexpr has been AND/OR flattened (actually,
322
* it's been through eval_const_expressions), but not converted to
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* implicit-AND form; and any SubLinks in it should already have been
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* converted to SubPlans. The subquery is as yet untouched, however.
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* The result is whatever we need to substitute in place of the SubLink
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* node in the executable expression. This will be either the SubPlan
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* node (if we have to do the subplan as a subplan), or a Param node
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* representing the result of an InitPlan, or a row comparison expression
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* tree containing InitPlan Param nodes.
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make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
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Node *testexpr, bool isTopQual)
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bool simple_exists = false;
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double tuple_fraction;
340
PlannerInfo *subroot;
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* Copy the source Query node. This is a quick and dirty kluge to resolve
345
* the fact that the parser can generate trees with multiple links to the
346
* same sub-Query node, but the planner wants to scribble on the Query.
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* Try to clean this up when we do querytree redesign...
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subquery = (Query *) copyObject(orig_subquery);
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* If it's an EXISTS subplan, we might be able to simplify it.
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if (subLinkType == EXISTS_SUBLINK)
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simple_exists = simplify_EXISTS_query(subquery);
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* For an EXISTS subplan, tell lower-level planner to expect that only the
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* first tuple will be retrieved. For ALL and ANY subplans, we will be
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* able to stop evaluating if the test condition fails or matches, so very
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* often not all the tuples will be retrieved; for lack of a better idea,
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* specify 50% retrieval. For EXPR and ROWCOMPARE subplans, use default
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* behavior (we're only expecting one row out, anyway).
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* NOTE: if you change these numbers, also change cost_subplan() in
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* XXX If an ANY subplan is uncorrelated, build_subplan may decide to hash
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* its output. In that case it would've been better to specify full
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* retrieval. At present, however, we can only check hashability after
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* we've made the subplan :-(. (Determining whether it'll fit in work_mem
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* is the really hard part.) Therefore, we don't want to be too
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* optimistic about the percentage of tuples retrieved, for fear of
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* selecting a plan that's bad for the materialization case.
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if (subLinkType == EXISTS_SUBLINK)
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tuple_fraction = 1.0; /* just like a LIMIT 1 */
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else if (subLinkType == ALL_SUBLINK ||
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subLinkType == ANY_SUBLINK)
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tuple_fraction = 0.5; /* 50% */
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tuple_fraction = 0.0; /* default behavior */
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* Generate the plan for the subquery.
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plan = subquery_planner(root->glob, subquery,
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false, tuple_fraction,
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/* And convert to SubPlan or InitPlan format. */
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result = build_subplan(root, plan,
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subroot->parse->rtable, subroot->rowMarks,
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subLinkType, testexpr, true, isTopQual);
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* If it's a correlated EXISTS with an unimportant targetlist, we might be
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* able to transform it to the equivalent of an IN and then implement it
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* by hashing. We don't have enough information yet to tell which way is
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* likely to be better (it depends on the expected number of executions of
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* the EXISTS qual, and we are much too early in planning the outer query
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* to be able to guess that). So we generate both plans, if possible, and
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* leave it to the executor to decide which to use.
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if (simple_exists && IsA(result, SubPlan))
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/* Make a second copy of the original subquery */
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subquery = (Query *) copyObject(orig_subquery);
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/* and re-simplify */
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simple_exists = simplify_EXISTS_query(subquery);
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Assert(simple_exists);
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/* See if it can be converted to an ANY query */
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subquery = convert_EXISTS_to_ANY(root, subquery,
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&newtestexpr, ¶mIds);
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/* Generate the plan for the ANY subquery; we'll need all rows */
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plan = subquery_planner(root->glob, subquery,
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/* Now we can check if it'll fit in work_mem */
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if (subplan_is_hashable(plan))
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AlternativeSubPlan *asplan;
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/* OK, convert to SubPlan format. */
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hashplan = (SubPlan *) build_subplan(root, plan,
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subroot->parse->rtable,
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ANY_SUBLINK, newtestexpr,
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/* Check we got what we expected */
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Assert(IsA(hashplan, SubPlan));
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Assert(hashplan->parParam == NIL);
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Assert(hashplan->useHashTable);
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/* build_subplan won't have filled in paramIds */
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hashplan->paramIds = paramIds;
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/* Leave it to the executor to decide which plan to use */
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asplan = makeNode(AlternativeSubPlan);
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asplan->subplans = list_make2(result, hashplan);
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result = (Node *) asplan;
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* Build a SubPlan node given the raw inputs --- subroutine for make_subplan
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* Returns either the SubPlan, or an expression using initplan output Params,
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* as explained in the comments for make_subplan.
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build_subplan(PlannerInfo *root, Plan *plan, List *rtable, List *rowmarks,
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SubLinkType subLinkType, Node *testexpr,
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bool adjust_testexpr, bool unknownEqFalse)
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* Initialize the SubPlan node. Note plan_id, plan_name, and cost fields
476
* are set further down.
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splan = makeNode(SubPlan);
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splan->subLinkType = subLinkType;
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splan->testexpr = NULL;
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splan->paramIds = NIL;
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get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod,
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&splan->firstColCollation);
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splan->useHashTable = false;
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splan->unknownEqFalse = unknownEqFalse;
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splan->setParam = NIL;
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splan->parParam = NIL;
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* Make parParam and args lists of param IDs and expressions that current
492
* query level will pass to this child plan.
494
tmpset = bms_copy(plan->extParam);
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while ((paramid = bms_first_member(tmpset)) >= 0)
497
PlannerParamItem *pitem = list_nth(root->glob->paramlist, paramid);
499
if (pitem->abslevel == root->query_level)
504
* The Var or Aggref has already been adjusted to have the correct
505
* varlevelsup or agglevelsup. We probably don't even need to
506
* copy it again, but be safe.
508
arg = copyObject(pitem->item);
511
* If it's an Aggref, its arguments might contain SubLinks, which
512
* have not yet been processed. Do that now.
514
if (IsA(arg, Aggref))
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arg = SS_process_sublinks(root, arg, false);
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splan->parParam = lappend_int(splan->parParam, paramid);
518
splan->args = lappend(splan->args, arg);
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* Un-correlated or undirect correlated plans of EXISTS, EXPR, ARRAY, or
525
* ROWCOMPARE types can be used as initPlans. For EXISTS, EXPR, or ARRAY,
526
* we just produce a Param referring to the result of evaluating the
527
* initPlan. For ROWCOMPARE, we must modify the testexpr tree to contain
528
* PARAM_EXEC Params instead of the PARAM_SUBLINK Params emitted by the
531
if (splan->parParam == NIL && subLinkType == EXISTS_SUBLINK)
535
Assert(testexpr == NULL);
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prm = generate_new_param(root, BOOLOID, -1, InvalidOid);
537
splan->setParam = list_make1_int(prm->paramid);
539
result = (Node *) prm;
541
else if (splan->parParam == NIL && subLinkType == EXPR_SUBLINK)
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TargetEntry *te = linitial(plan->targetlist);
546
Assert(!te->resjunk);
547
Assert(testexpr == NULL);
548
prm = generate_new_param(root,
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exprType((Node *) te->expr),
550
exprTypmod((Node *) te->expr),
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exprCollation((Node *) te->expr));
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splan->setParam = list_make1_int(prm->paramid);
554
result = (Node *) prm;
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else if (splan->parParam == NIL && subLinkType == ARRAY_SUBLINK)
558
TargetEntry *te = linitial(plan->targetlist);
562
Assert(!te->resjunk);
563
Assert(testexpr == NULL);
564
arraytype = get_array_type(exprType((Node *) te->expr));
565
if (!OidIsValid(arraytype))
566
elog(ERROR, "could not find array type for datatype %s",
567
format_type_be(exprType((Node *) te->expr)));
568
prm = generate_new_param(root,
570
exprTypmod((Node *) te->expr),
571
exprCollation((Node *) te->expr));
572
splan->setParam = list_make1_int(prm->paramid);
574
result = (Node *) prm;
576
else if (splan->parParam == NIL && subLinkType == ROWCOMPARE_SUBLINK)
578
/* Adjust the Params */
581
Assert(testexpr != NULL);
582
params = generate_subquery_params(root,
585
result = convert_testexpr(root,
588
splan->setParam = list_copy(splan->paramIds);
592
* The executable expression is returned to become part of the outer
593
* plan's expression tree; it is not kept in the initplan node.
599
* Adjust the Params in the testexpr, unless caller said it's not
602
if (testexpr && adjust_testexpr)
606
params = generate_subquery_params(root,
609
splan->testexpr = convert_testexpr(root,
614
splan->testexpr = testexpr;
617
* We can't convert subplans of ALL_SUBLINK or ANY_SUBLINK types to
618
* initPlans, even when they are uncorrelated or undirect correlated,
619
* because we need to scan the output of the subplan for each outer
620
* tuple. But if it's a not-direct-correlated IN (= ANY) test, we
621
* might be able to use a hashtable to avoid comparing all the tuples.
623
if (subLinkType == ANY_SUBLINK &&
624
splan->parParam == NIL &&
625
subplan_is_hashable(plan) &&
626
testexpr_is_hashable(splan->testexpr))
627
splan->useHashTable = true;
630
* Otherwise, we have the option to tack a Material node onto the top
631
* of the subplan, to reduce the cost of reading it repeatedly. This
632
* is pointless for a direct-correlated subplan, since we'd have to
633
* recompute its results each time anyway. For uncorrelated/undirect
634
* correlated subplans, we add Material unless the subplan's top plan
635
* node would materialize its output anyway. Also, if enable_material
636
* is false, then the user does not want us to materialize anything
637
* unnecessarily, so we don't.
639
else if (splan->parParam == NIL && enable_material &&
640
!ExecMaterializesOutput(nodeTag(plan)))
641
plan = materialize_finished_plan(plan);
643
result = (Node *) splan;
648
* Add the subplan and its rtable to the global lists.
650
root->glob->subplans = lappend(root->glob->subplans, plan);
651
root->glob->subrtables = lappend(root->glob->subrtables, rtable);
652
root->glob->subrowmarks = lappend(root->glob->subrowmarks, rowmarks);
653
splan->plan_id = list_length(root->glob->subplans);
656
root->init_plans = lappend(root->init_plans, splan);
659
* A parameterless subplan (not initplan) should be prepared to handle
660
* REWIND efficiently. If it has direct parameters then there's no point
661
* since it'll be reset on each scan anyway; and if it's an initplan then
662
* there's no point since it won't get re-run without parameter changes
663
* anyway. The input of a hashed subplan doesn't need REWIND either.
665
if (splan->parParam == NIL && !isInitPlan && !splan->useHashTable)
666
root->glob->rewindPlanIDs = bms_add_member(root->glob->rewindPlanIDs,
669
/* Label the subplan for EXPLAIN purposes */
675
splan->plan_name = palloc(32 + 12 * list_length(splan->setParam));
676
sprintf(splan->plan_name, "InitPlan %d (returns ", splan->plan_id);
677
offset = strlen(splan->plan_name);
678
foreach(lc, splan->setParam)
680
sprintf(splan->plan_name + offset, "$%d%s",
682
lnext(lc) ? "," : "");
683
offset += strlen(splan->plan_name + offset);
685
sprintf(splan->plan_name + offset, ")");
689
splan->plan_name = palloc(32);
690
sprintf(splan->plan_name, "SubPlan %d", splan->plan_id);
693
/* Lastly, fill in the cost estimates for use later */
694
cost_subplan(root, splan, plan);
700
* generate_subquery_params: build a list of Params representing the output
701
* columns of a sublink's sub-select, given the sub-select's targetlist.
703
* We also return an integer list of the paramids of the Params.
706
generate_subquery_params(PlannerInfo *root, List *tlist, List **paramIds)
715
TargetEntry *tent = (TargetEntry *) lfirst(lc);
721
param = generate_new_param(root,
722
exprType((Node *) tent->expr),
723
exprTypmod((Node *) tent->expr),
724
exprCollation((Node *) tent->expr));
725
result = lappend(result, param);
726
ids = lappend_int(ids, param->paramid);
734
* generate_subquery_vars: build a list of Vars representing the output
735
* columns of a sublink's sub-select, given the sub-select's targetlist.
736
* The Vars have the specified varno (RTE index).
739
generate_subquery_vars(PlannerInfo *root, List *tlist, Index varno)
747
TargetEntry *tent = (TargetEntry *) lfirst(lc);
753
var = makeVarFromTargetEntry(varno, tent);
754
result = lappend(result, var);
761
* convert_testexpr: convert the testexpr given by the parser into
762
* actually executable form. This entails replacing PARAM_SUBLINK Params
763
* with Params or Vars representing the results of the sub-select. The
764
* nodes to be substituted are passed in as the List result from
765
* generate_subquery_params or generate_subquery_vars.
767
* The given testexpr has already been recursively processed by
768
* process_sublinks_mutator. Hence it can no longer contain any
769
* PARAM_SUBLINK Params for lower SubLink nodes; we can safely assume that
770
* any we find are for our own level of SubLink.
773
convert_testexpr(PlannerInfo *root,
777
convert_testexpr_context context;
780
context.subst_nodes = subst_nodes;
781
return convert_testexpr_mutator(testexpr, &context);
785
convert_testexpr_mutator(Node *node,
786
convert_testexpr_context *context)
790
if (IsA(node, Param))
792
Param *param = (Param *) node;
794
if (param->paramkind == PARAM_SUBLINK)
796
if (param->paramid <= 0 ||
797
param->paramid > list_length(context->subst_nodes))
798
elog(ERROR, "unexpected PARAM_SUBLINK ID: %d", param->paramid);
801
* We copy the list item to avoid having doubly-linked
802
* substructure in the modified parse tree. This is probably
803
* unnecessary when it's a Param, but be safe.
805
return (Node *) copyObject(list_nth(context->subst_nodes,
806
param->paramid - 1));
809
return expression_tree_mutator(node,
810
convert_testexpr_mutator,
815
* subplan_is_hashable: can we implement an ANY subplan by hashing?
818
subplan_is_hashable(Plan *plan)
820
double subquery_size;
823
* The estimated size of the subquery result must fit in work_mem. (Note:
824
* we use sizeof(HeapTupleHeaderData) here even though the tuples will
825
* actually be stored as MinimalTuples; this provides some fudge factor
826
* for hashtable overhead.)
828
subquery_size = plan->plan_rows *
829
(MAXALIGN(plan->plan_width) + MAXALIGN(sizeof(HeapTupleHeaderData)));
830
if (subquery_size > work_mem * 1024L)
837
* testexpr_is_hashable: is an ANY SubLink's test expression hashable?
840
testexpr_is_hashable(Node *testexpr)
843
* The testexpr must be a single OpExpr, or an AND-clause containing only
846
* The combining operators must be hashable and strict. The need for
847
* hashability is obvious, since we want to use hashing. Without
848
* strictness, behavior in the presence of nulls is too unpredictable. We
849
* actually must assume even more than plain strictness: they can't yield
850
* NULL for non-null inputs, either (see nodeSubplan.c). However, hash
851
* indexes and hash joins assume that too.
853
if (testexpr && IsA(testexpr, OpExpr))
855
if (hash_ok_operator((OpExpr *) testexpr))
858
else if (and_clause(testexpr))
862
foreach(l, ((BoolExpr *) testexpr)->args)
864
Node *andarg = (Node *) lfirst(l);
866
if (!IsA(andarg, OpExpr))
868
if (!hash_ok_operator((OpExpr *) andarg))
878
* Check expression is hashable + strict
880
* We could use op_hashjoinable() and op_strict(), but do it like this to
881
* avoid a redundant cache lookup.
884
hash_ok_operator(OpExpr *expr)
886
Oid opid = expr->opno;
888
/* quick out if not a binary operator */
889
if (list_length(expr->args) != 2)
891
if (opid == ARRAY_EQ_OP)
893
/* array_eq is strict, but must check input type to ensure hashable */
894
Node *leftarg = linitial(expr->args);
896
return op_hashjoinable(opid, exprType(leftarg));
900
/* else must look up the operator properties */
902
Form_pg_operator optup;
904
tup = SearchSysCache1(OPEROID, ObjectIdGetDatum(opid));
905
if (!HeapTupleIsValid(tup))
906
elog(ERROR, "cache lookup failed for operator %u", opid);
907
optup = (Form_pg_operator) GETSTRUCT(tup);
908
if (!optup->oprcanhash || !func_strict(optup->oprcode))
910
ReleaseSysCache(tup);
913
ReleaseSysCache(tup);
920
* SS_process_ctes: process a query's WITH list
922
* We plan each interesting WITH item and convert it to an initplan.
923
* A side effect is to fill in root->cte_plan_ids with a list that
924
* parallels root->parse->cteList and provides the subplan ID for
925
* each CTE's initplan.
928
SS_process_ctes(PlannerInfo *root)
932
Assert(root->cte_plan_ids == NIL);
934
foreach(lc, root->parse->cteList)
936
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
937
CmdType cmdType = ((Query *) cte->ctequery)->commandType;
940
PlannerInfo *subroot;
947
* Ignore SELECT CTEs that are not actually referenced anywhere.
949
if (cte->cterefcount == 0 && cmdType == CMD_SELECT)
951
/* Make a dummy entry in cte_plan_ids */
952
root->cte_plan_ids = lappend_int(root->cte_plan_ids, -1);
957
* Copy the source Query node. Probably not necessary, but let's keep
958
* this similar to make_subplan.
960
subquery = (Query *) copyObject(cte->ctequery);
963
* Generate the plan for the CTE query. Always plan for full
964
* retrieval --- we don't have enough info to predict otherwise.
966
plan = subquery_planner(root->glob, subquery,
968
cte->cterecursive, 0.0,
972
* Make a SubPlan node for it. This is just enough unlike
973
* build_subplan that we can't share code.
975
* Note plan_id, plan_name, and cost fields are set further down.
977
splan = makeNode(SubPlan);
978
splan->subLinkType = CTE_SUBLINK;
979
splan->testexpr = NULL;
980
splan->paramIds = NIL;
981
get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod,
982
&splan->firstColCollation);
983
splan->useHashTable = false;
984
splan->unknownEqFalse = false;
985
splan->setParam = NIL;
986
splan->parParam = NIL;
990
* Make parParam and args lists of param IDs and expressions that
991
* current query level will pass to this child plan. Even though this
992
* is an initplan, there could be side-references to earlier
993
* initplan's outputs, specifically their CTE output parameters.
995
tmpset = bms_copy(plan->extParam);
996
while ((paramid = bms_first_member(tmpset)) >= 0)
998
PlannerParamItem *pitem = list_nth(root->glob->paramlist, paramid);
1000
if (pitem->abslevel == root->query_level)
1002
prm = (Param *) pitem->item;
1003
if (!IsA(prm, Param) ||
1004
prm->paramtype != INTERNALOID)
1005
elog(ERROR, "bogus local parameter passed to WITH query");
1007
splan->parParam = lappend_int(splan->parParam, paramid);
1008
splan->args = lappend(splan->args, copyObject(prm));
1014
* Assign a param to represent the query output. We only really care
1015
* about reserving a parameter ID number.
1017
prm = generate_new_param(root, INTERNALOID, -1, InvalidOid);
1018
splan->setParam = list_make1_int(prm->paramid);
1021
* Add the subplan and its rtable to the global lists.
1023
root->glob->subplans = lappend(root->glob->subplans, plan);
1024
root->glob->subrtables = lappend(root->glob->subrtables,
1025
subroot->parse->rtable);
1026
root->glob->subrowmarks = lappend(root->glob->subrowmarks,
1028
splan->plan_id = list_length(root->glob->subplans);
1030
root->init_plans = lappend(root->init_plans, splan);
1032
root->cte_plan_ids = lappend_int(root->cte_plan_ids, splan->plan_id);
1034
/* Label the subplan for EXPLAIN purposes */
1035
splan->plan_name = palloc(4 + strlen(cte->ctename) + 1);
1036
sprintf(splan->plan_name, "CTE %s", cte->ctename);
1038
/* Lastly, fill in the cost estimates for use later */
1039
cost_subplan(root, splan, plan);
1044
* convert_ANY_sublink_to_join: try to convert an ANY SubLink to a join
1046
* The caller has found an ANY SubLink at the top level of one of the query's
1047
* qual clauses, but has not checked the properties of the SubLink further.
1048
* Decide whether it is appropriate to process this SubLink in join style.
1049
* If so, form a JoinExpr and return it. Return NULL if the SubLink cannot
1050
* be converted to a join.
1052
* The only non-obvious input parameter is available_rels: this is the set
1053
* of query rels that can safely be referenced in the sublink expression.
1054
* (We must restrict this to avoid changing the semantics when a sublink
1055
* is present in an outer join's ON qual.) The conversion must fail if
1056
* the converted qual would reference any but these parent-query relids.
1058
* On success, the returned JoinExpr has larg = NULL and rarg = the jointree
1059
* item representing the pulled-up subquery. The caller must set larg to
1060
* represent the relation(s) on the lefthand side of the new join, and insert
1061
* the JoinExpr into the upper query's jointree at an appropriate place
1062
* (typically, where the lefthand relation(s) had been). Note that the
1063
* passed-in SubLink must also be removed from its original position in the
1064
* query quals, since the quals of the returned JoinExpr replace it.
1065
* (Notionally, we replace the SubLink with a constant TRUE, then elide the
1066
* redundant constant from the qual.)
1068
* Side effects of a successful conversion include adding the SubLink's
1069
* subselect to the query's rangetable, so that it can be referenced in
1070
* the JoinExpr's rarg.
1073
convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink,
1074
Relids available_rels)
1077
Query *parse = root->parse;
1078
Query *subselect = (Query *) sublink->subselect;
1079
Relids upper_varnos;
1083
List *subquery_vars;
1086
Assert(sublink->subLinkType == ANY_SUBLINK);
1089
* The sub-select must not refer to any Vars of the parent query. (Vars of
1090
* higher levels should be okay, though.)
1092
if (contain_vars_of_level((Node *) subselect, 1))
1096
* The test expression must contain some Vars of the parent query, else
1097
* it's not gonna be a join. (Note that it won't have Vars referring to
1098
* the subquery, rather Params.)
1100
upper_varnos = pull_varnos(sublink->testexpr);
1101
if (bms_is_empty(upper_varnos))
1105
* However, it can't refer to anything outside available_rels.
1107
if (!bms_is_subset(upper_varnos, available_rels))
1111
* The combining operators and left-hand expressions mustn't be volatile.
1113
if (contain_volatile_functions(sublink->testexpr))
1117
* Okay, pull up the sub-select into upper range table.
1119
* We rely here on the assumption that the outer query has no references
1120
* to the inner (necessarily true, other than the Vars that we build
1121
* below). Therefore this is a lot easier than what pull_up_subqueries has
1124
rte = addRangeTableEntryForSubquery(NULL,
1126
makeAlias("ANY_subquery", NIL),
1128
parse->rtable = lappend(parse->rtable, rte);
1129
rtindex = list_length(parse->rtable);
1132
* Form a RangeTblRef for the pulled-up sub-select.
1134
rtr = makeNode(RangeTblRef);
1135
rtr->rtindex = rtindex;
1138
* Build a list of Vars representing the subselect outputs.
1140
subquery_vars = generate_subquery_vars(root,
1141
subselect->targetList,
1145
* Build the new join's qual expression, replacing Params with these Vars.
1147
quals = convert_testexpr(root, sublink->testexpr, subquery_vars);
1150
* And finally, build the JoinExpr node.
1152
result = makeNode(JoinExpr);
1153
result->jointype = JOIN_SEMI;
1154
result->isNatural = false;
1155
result->larg = NULL; /* caller must fill this in */
1156
result->rarg = (Node *) rtr;
1157
result->usingClause = NIL;
1158
result->quals = quals;
1159
result->alias = NULL;
1160
result->rtindex = 0; /* we don't need an RTE for it */
1166
* convert_EXISTS_sublink_to_join: try to convert an EXISTS SubLink to a join
1168
* The API of this function is identical to convert_ANY_sublink_to_join's,
1169
* except that we also support the case where the caller has found NOT EXISTS,
1170
* so we need an additional input parameter "under_not".
1173
convert_EXISTS_sublink_to_join(PlannerInfo *root, SubLink *sublink,
1174
bool under_not, Relids available_rels)
1177
Query *parse = root->parse;
1178
Query *subselect = (Query *) sublink->subselect;
1182
Relids clause_varnos;
1183
Relids upper_varnos;
1185
Assert(sublink->subLinkType == EXISTS_SUBLINK);
1188
* Can't flatten if it contains WITH. (We could arrange to pull up the
1189
* WITH into the parent query's cteList, but that risks changing the
1190
* semantics, since a WITH ought to be executed once per associated query
1191
* call.) Note that convert_ANY_sublink_to_join doesn't have to reject
1192
* this case, since it just produces a subquery RTE that doesn't have to
1193
* get flattened into the parent query.
1195
if (subselect->cteList)
1199
* Copy the subquery so we can modify it safely (see comments in
1202
subselect = (Query *) copyObject(subselect);
1205
* See if the subquery can be simplified based on the knowledge that it's
1206
* being used in EXISTS(). If we aren't able to get rid of its
1207
* targetlist, we have to fail, because the pullup operation leaves us
1208
* with noplace to evaluate the targetlist.
1210
if (!simplify_EXISTS_query(subselect))
1214
* The subquery must have a nonempty jointree, else we won't have a join.
1216
if (subselect->jointree->fromlist == NIL)
1220
* Separate out the WHERE clause. (We could theoretically also remove
1221
* top-level plain JOIN/ON clauses, but it's probably not worth the
1224
whereClause = subselect->jointree->quals;
1225
subselect->jointree->quals = NULL;
1228
* The rest of the sub-select must not refer to any Vars of the parent
1229
* query. (Vars of higher levels should be okay, though.)
1231
if (contain_vars_of_level((Node *) subselect, 1))
1235
* On the other hand, the WHERE clause must contain some Vars of the
1236
* parent query, else it's not gonna be a join.
1238
if (!contain_vars_of_level(whereClause, 1))
1242
* We don't risk optimizing if the WHERE clause is volatile, either.
1244
if (contain_volatile_functions(whereClause))
1248
* Prepare to pull up the sub-select into top range table.
1250
* We rely here on the assumption that the outer query has no references
1251
* to the inner (necessarily true). Therefore this is a lot easier than
1252
* what pull_up_subqueries has to go through.
1254
* In fact, it's even easier than what convert_ANY_sublink_to_join has to
1255
* do. The machinations of simplify_EXISTS_query ensured that there is
1256
* nothing interesting in the subquery except an rtable and jointree, and
1257
* even the jointree FromExpr no longer has quals. So we can just append
1258
* the rtable to our own and use the FromExpr in our jointree. But first,
1259
* adjust all level-zero varnos in the subquery to account for the rtable
1262
rtoffset = list_length(parse->rtable);
1263
OffsetVarNodes((Node *) subselect, rtoffset, 0);
1264
OffsetVarNodes(whereClause, rtoffset, 0);
1267
* Upper-level vars in subquery will now be one level closer to their
1268
* parent than before; in particular, anything that had been level 1
1269
* becomes level zero.
1271
IncrementVarSublevelsUp((Node *) subselect, -1, 1);
1272
IncrementVarSublevelsUp(whereClause, -1, 1);
1275
* Now that the WHERE clause is adjusted to match the parent query
1276
* environment, we can easily identify all the level-zero rels it uses.
1277
* The ones <= rtoffset belong to the upper query; the ones > rtoffset do
1280
clause_varnos = pull_varnos(whereClause);
1281
upper_varnos = NULL;
1282
while ((varno = bms_first_member(clause_varnos)) >= 0)
1284
if (varno <= rtoffset)
1285
upper_varnos = bms_add_member(upper_varnos, varno);
1287
bms_free(clause_varnos);
1288
Assert(!bms_is_empty(upper_varnos));
1291
* Now that we've got the set of upper-level varnos, we can make the last
1292
* check: only available_rels can be referenced.
1294
if (!bms_is_subset(upper_varnos, available_rels))
1297
/* Now we can attach the modified subquery rtable to the parent */
1298
parse->rtable = list_concat(parse->rtable, subselect->rtable);
1301
* And finally, build the JoinExpr node.
1303
result = makeNode(JoinExpr);
1304
result->jointype = under_not ? JOIN_ANTI : JOIN_SEMI;
1305
result->isNatural = false;
1306
result->larg = NULL; /* caller must fill this in */
1307
/* flatten out the FromExpr node if it's useless */
1308
if (list_length(subselect->jointree->fromlist) == 1)
1309
result->rarg = (Node *) linitial(subselect->jointree->fromlist);
1311
result->rarg = (Node *) subselect->jointree;
1312
result->usingClause = NIL;
1313
result->quals = whereClause;
1314
result->alias = NULL;
1315
result->rtindex = 0; /* we don't need an RTE for it */
1321
* simplify_EXISTS_query: remove any useless stuff in an EXISTS's subquery
1323
* The only thing that matters about an EXISTS query is whether it returns
1324
* zero or more than zero rows. Therefore, we can remove certain SQL features
1325
* that won't affect that. The only part that is really likely to matter in
1326
* typical usage is simplifying the targetlist: it's a common habit to write
1327
* "SELECT * FROM" even though there is no need to evaluate any columns.
1329
* Note: by suppressing the targetlist we could cause an observable behavioral
1330
* change, namely that any errors that might occur in evaluating the tlist
1331
* won't occur, nor will other side-effects of volatile functions. This seems
1332
* unlikely to bother anyone in practice.
1334
* Returns TRUE if was able to discard the targetlist, else FALSE.
1337
simplify_EXISTS_query(Query *query)
1340
* We don't try to simplify at all if the query uses set operations,
1341
* aggregates, modifying CTEs, HAVING, LIMIT/OFFSET, or FOR UPDATE/SHARE;
1342
* none of these seem likely in normal usage and their possible effects
1345
if (query->commandType != CMD_SELECT ||
1346
query->intoClause ||
1347
query->setOperations ||
1349
query->hasWindowFuncs ||
1350
query->hasModifyingCTE ||
1351
query->havingQual ||
1352
query->limitOffset ||
1353
query->limitCount ||
1358
* Mustn't throw away the targetlist if it contains set-returning
1359
* functions; those could affect whether zero rows are returned!
1361
if (expression_returns_set((Node *) query->targetList))
1365
* Otherwise, we can throw away the targetlist, as well as any GROUP,
1366
* WINDOW, DISTINCT, and ORDER BY clauses; none of those clauses will
1367
* change a nonzero-rows result to zero rows or vice versa. (Furthermore,
1368
* since our parsetree representation of these clauses depends on the
1369
* targetlist, we'd better throw them away if we drop the targetlist.)
1371
query->targetList = NIL;
1372
query->groupClause = NIL;
1373
query->windowClause = NIL;
1374
query->distinctClause = NIL;
1375
query->sortClause = NIL;
1376
query->hasDistinctOn = false;
1382
* convert_EXISTS_to_ANY: try to convert EXISTS to a hashable ANY sublink
1384
* The subselect is expected to be a fresh copy that we can munge up,
1385
* and to have been successfully passed through simplify_EXISTS_query.
1387
* On success, the modified subselect is returned, and we store a suitable
1388
* upper-level test expression at *testexpr, plus a list of the subselect's
1389
* output Params at *paramIds. (The test expression is already Param-ified
1390
* and hence need not go through convert_testexpr, which is why we have to
1391
* deal with the Param IDs specially.)
1393
* On failure, returns NULL.
1396
convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect,
1397
Node **testexpr, List **paramIds)
1415
* Query must not require a targetlist, since we have to insert a new one.
1416
* Caller should have dealt with the case already.
1418
Assert(subselect->targetList == NIL);
1421
* Separate out the WHERE clause. (We could theoretically also remove
1422
* top-level plain JOIN/ON clauses, but it's probably not worth the
1425
whereClause = subselect->jointree->quals;
1426
subselect->jointree->quals = NULL;
1429
* The rest of the sub-select must not refer to any Vars of the parent
1430
* query. (Vars of higher levels should be okay, though.)
1432
* Note: we need not check for Aggrefs separately because we know the
1433
* sub-select is as yet unoptimized; any uplevel Aggref must therefore
1434
* contain an uplevel Var reference. This is not the case below ...
1436
if (contain_vars_of_level((Node *) subselect, 1))
1440
* We don't risk optimizing if the WHERE clause is volatile, either.
1442
if (contain_volatile_functions(whereClause))
1446
* Clean up the WHERE clause by doing const-simplification etc on it.
1447
* Aside from simplifying the processing we're about to do, this is
1448
* important for being able to pull chunks of the WHERE clause up into the
1449
* parent query. Since we are invoked partway through the parent's
1450
* preprocess_expression() work, earlier steps of preprocess_expression()
1451
* wouldn't get applied to the pulled-up stuff unless we do them here. For
1452
* the parts of the WHERE clause that get put back into the child query,
1453
* this work is partially duplicative, but it shouldn't hurt.
1455
* Note: we do not run flatten_join_alias_vars. This is OK because any
1456
* parent aliases were flattened already, and we're not going to pull any
1457
* child Vars (of any description) into the parent.
1459
* Note: passing the parent's root to eval_const_expressions is
1460
* technically wrong, but we can get away with it since only the
1461
* boundParams (if any) are used, and those would be the same in a
1464
whereClause = eval_const_expressions(root, whereClause);
1465
whereClause = (Node *) canonicalize_qual((Expr *) whereClause);
1466
whereClause = (Node *) make_ands_implicit((Expr *) whereClause);
1469
* We now have a flattened implicit-AND list of clauses, which we try to
1470
* break apart into "outervar = innervar" hash clauses. Anything that
1471
* can't be broken apart just goes back into the newWhere list. Note that
1472
* we aren't trying hard yet to ensure that we have only outer or only
1473
* inner on each side; we'll check that if we get to the end.
1475
leftargs = rightargs = opids = opcollations = newWhere = NIL;
1476
foreach(lc, (List *) whereClause)
1478
OpExpr *expr = (OpExpr *) lfirst(lc);
1480
if (IsA(expr, OpExpr) &&
1481
hash_ok_operator(expr))
1483
Node *leftarg = (Node *) linitial(expr->args);
1484
Node *rightarg = (Node *) lsecond(expr->args);
1486
if (contain_vars_of_level(leftarg, 1))
1488
leftargs = lappend(leftargs, leftarg);
1489
rightargs = lappend(rightargs, rightarg);
1490
opids = lappend_oid(opids, expr->opno);
1491
opcollations = lappend_oid(opcollations, expr->inputcollid);
1494
if (contain_vars_of_level(rightarg, 1))
1497
* We must commute the clause to put the outer var on the
1498
* left, because the hashing code in nodeSubplan.c expects
1499
* that. This probably shouldn't ever fail, since hashable
1500
* operators ought to have commutators, but be paranoid.
1502
expr->opno = get_commutator(expr->opno);
1503
if (OidIsValid(expr->opno) && hash_ok_operator(expr))
1505
leftargs = lappend(leftargs, rightarg);
1506
rightargs = lappend(rightargs, leftarg);
1507
opids = lappend_oid(opids, expr->opno);
1508
opcollations = lappend_oid(opcollations, expr->inputcollid);
1511
/* If no commutator, no chance to optimize the WHERE clause */
1515
/* Couldn't handle it as a hash clause */
1516
newWhere = lappend(newWhere, expr);
1520
* If we didn't find anything we could convert, fail.
1522
if (leftargs == NIL)
1526
* There mustn't be any parent Vars or Aggs in the stuff that we intend to
1527
* put back into the child query. Note: you might think we don't need to
1528
* check for Aggs separately, because an uplevel Agg must contain an
1529
* uplevel Var in its argument. But it is possible that the uplevel Var
1530
* got optimized away by eval_const_expressions. Consider
1532
* SUM(CASE WHEN false THEN uplevelvar ELSE 0 END)
1534
if (contain_vars_of_level((Node *) newWhere, 1) ||
1535
contain_vars_of_level((Node *) rightargs, 1))
1537
if (root->parse->hasAggs &&
1538
(contain_aggs_of_level((Node *) newWhere, 1) ||
1539
contain_aggs_of_level((Node *) rightargs, 1)))
1543
* And there can't be any child Vars in the stuff we intend to pull up.
1544
* (Note: we'd need to check for child Aggs too, except we know the child
1545
* has no aggs at all because of simplify_EXISTS_query's check. The same
1546
* goes for window functions.)
1548
if (contain_vars_of_level((Node *) leftargs, 0))
1552
* Also reject sublinks in the stuff we intend to pull up. (It might be
1553
* possible to support this, but doesn't seem worth the complication.)
1555
if (contain_subplans((Node *) leftargs))
1559
* Okay, adjust the sublevelsup in the stuff we're pulling up.
1561
IncrementVarSublevelsUp((Node *) leftargs, -1, 1);
1564
* Put back any child-level-only WHERE clauses.
1567
subselect->jointree->quals = (Node *) make_ands_explicit(newWhere);
1570
* Build a new targetlist for the child that emits the expressions we
1571
* need. Concurrently, build a testexpr for the parent using Params to
1572
* reference the child outputs. (Since we generate Params directly here,
1573
* there will be no need to convert the testexpr in build_subplan.)
1575
tlist = testlist = paramids = NIL;
1577
/* there's no "forfour" so we have to chase one of the lists manually */
1578
cc = list_head(opcollations);
1579
forthree(lc, leftargs, rc, rightargs, oc, opids)
1581
Node *leftarg = (Node *) lfirst(lc);
1582
Node *rightarg = (Node *) lfirst(rc);
1583
Oid opid = lfirst_oid(oc);
1584
Oid opcollation = lfirst_oid(cc);
1588
param = generate_new_param(root,
1590
exprTypmod(rightarg),
1591
exprCollation(rightarg));
1592
tlist = lappend(tlist,
1593
makeTargetEntry((Expr *) rightarg,
1597
testlist = lappend(testlist,
1598
make_opclause(opid, BOOLOID, false,
1599
(Expr *) leftarg, (Expr *) param,
1600
InvalidOid, opcollation));
1601
paramids = lappend_int(paramids, param->paramid);
1604
/* Put everything where it should go, and we're done */
1605
subselect->targetList = tlist;
1606
*testexpr = (Node *) make_ands_explicit(testlist);
1607
*paramIds = paramids;
1614
* Replace correlation vars (uplevel vars) with Params.
1616
* Uplevel aggregates are replaced, too.
1618
* Note: it is critical that this runs immediately after SS_process_sublinks.
1619
* Since we do not recurse into the arguments of uplevel aggregates, they will
1620
* get copied to the appropriate subplan args list in the parent query with
1621
* uplevel vars not replaced by Params, but only adjusted in level (see
1622
* replace_outer_agg). That's exactly what we want for the vars of the parent
1623
* level --- but if an aggregate's argument contains any further-up variables,
1624
* they have to be replaced with Params in their turn. That will happen when
1625
* the parent level runs SS_replace_correlation_vars. Therefore it must do
1626
* so after expanding its sublinks to subplans. And we don't want any steps
1627
* in between, else those steps would never get applied to the aggregate
1628
* argument expressions, either in the parent or the child level.
1630
* Another fairly tricky thing going on here is the handling of SubLinks in
1631
* the arguments of uplevel aggregates. Those are not touched inside the
1632
* intermediate query level, either. Instead, SS_process_sublinks recurses
1633
* on them after copying the Aggref expression into the parent plan level
1634
* (this is actually taken care of in build_subplan).
1637
SS_replace_correlation_vars(PlannerInfo *root, Node *expr)
1639
/* No setup needed for tree walk, so away we go */
1640
return replace_correlation_vars_mutator(expr, root);
1644
replace_correlation_vars_mutator(Node *node, PlannerInfo *root)
1650
if (((Var *) node)->varlevelsup > 0)
1651
return (Node *) replace_outer_var(root, (Var *) node);
1653
if (IsA(node, Aggref))
1655
if (((Aggref *) node)->agglevelsup > 0)
1656
return (Node *) replace_outer_agg(root, (Aggref *) node);
1658
return expression_tree_mutator(node,
1659
replace_correlation_vars_mutator,
1664
* Expand SubLinks to SubPlans in the given expression.
1666
* The isQual argument tells whether or not this expression is a WHERE/HAVING
1667
* qualifier expression. If it is, any sublinks appearing at top level need
1668
* not distinguish FALSE from UNKNOWN return values.
1671
SS_process_sublinks(PlannerInfo *root, Node *expr, bool isQual)
1673
process_sublinks_context context;
1675
context.root = root;
1676
context.isTopQual = isQual;
1677
return process_sublinks_mutator(expr, &context);
1681
process_sublinks_mutator(Node *node, process_sublinks_context *context)
1683
process_sublinks_context locContext;
1685
locContext.root = context->root;
1689
if (IsA(node, SubLink))
1691
SubLink *sublink = (SubLink *) node;
1695
* First, recursively process the lefthand-side expressions, if any.
1696
* They're not top-level anymore.
1698
locContext.isTopQual = false;
1699
testexpr = process_sublinks_mutator(sublink->testexpr, &locContext);
1702
* Now build the SubPlan node and make the expr to return.
1704
return make_subplan(context->root,
1705
(Query *) sublink->subselect,
1706
sublink->subLinkType,
1708
context->isTopQual);
1712
* Don't recurse into the arguments of an outer aggregate here. Any
1713
* SubLinks in the arguments have to be dealt with at the outer query
1714
* level; they'll be handled when build_subplan collects the Aggref into
1715
* the arguments to be passed down to the current subplan.
1717
if (IsA(node, Aggref))
1719
if (((Aggref *) node)->agglevelsup > 0)
1724
* We should never see a SubPlan expression in the input (since this is
1725
* the very routine that creates 'em to begin with). We shouldn't find
1726
* ourselves invoked directly on a Query, either.
1728
Assert(!IsA(node, SubPlan));
1729
Assert(!IsA(node, AlternativeSubPlan));
1730
Assert(!IsA(node, Query));
1733
* Because make_subplan() could return an AND or OR clause, we have to
1734
* take steps to preserve AND/OR flatness of a qual. We assume the input
1735
* has been AND/OR flattened and so we need no recursion here.
1737
* (Due to the coding here, we will not get called on the List subnodes of
1738
* an AND; and the input is *not* yet in implicit-AND format. So no check
1739
* is needed for a bare List.)
1741
* Anywhere within the top-level AND/OR clause structure, we can tell
1742
* make_subplan() that NULL and FALSE are interchangeable. So isTopQual
1743
* propagates down in both cases. (Note that this is unlike the meaning
1744
* of "top level qual" used in most other places in Postgres.)
1746
if (and_clause(node))
1748
List *newargs = NIL;
1751
/* Still at qual top-level */
1752
locContext.isTopQual = context->isTopQual;
1754
foreach(l, ((BoolExpr *) node)->args)
1758
newarg = process_sublinks_mutator(lfirst(l), &locContext);
1759
if (and_clause(newarg))
1760
newargs = list_concat(newargs, ((BoolExpr *) newarg)->args);
1762
newargs = lappend(newargs, newarg);
1764
return (Node *) make_andclause(newargs);
1767
if (or_clause(node))
1769
List *newargs = NIL;
1772
/* Still at qual top-level */
1773
locContext.isTopQual = context->isTopQual;
1775
foreach(l, ((BoolExpr *) node)->args)
1779
newarg = process_sublinks_mutator(lfirst(l), &locContext);
1780
if (or_clause(newarg))
1781
newargs = list_concat(newargs, ((BoolExpr *) newarg)->args);
1783
newargs = lappend(newargs, newarg);
1785
return (Node *) make_orclause(newargs);
1789
* If we recurse down through anything other than an AND or OR node, we
1790
* are definitely not at top qual level anymore.
1792
locContext.isTopQual = false;
1794
return expression_tree_mutator(node,
1795
process_sublinks_mutator,
1796
(void *) &locContext);
1800
* SS_finalize_plan - do final sublink and parameter processing for a
1803
* This recursively computes the extParam and allParam sets for every Plan
1804
* node in the given plan tree. It also optionally attaches any previously
1805
* generated InitPlans to the top plan node. (Any InitPlans should already
1806
* have been put through SS_finalize_plan.)
1809
SS_finalize_plan(PlannerInfo *root, Plan *plan, bool attach_initplans)
1811
Bitmapset *valid_params,
1819
* Examine any initPlans to determine the set of external params they
1820
* reference, the set of output params they supply, and their total cost.
1821
* We'll use at least some of this info below. (Note we are assuming that
1822
* finalize_plan doesn't touch the initPlans.)
1824
* In the case where attach_initplans is false, we are assuming that the
1825
* existing initPlans are siblings that might supply params needed by the
1828
initExtParam = initSetParam = NULL;
1830
foreach(l, root->init_plans)
1832
SubPlan *initsubplan = (SubPlan *) lfirst(l);
1833
Plan *initplan = planner_subplan_get_plan(root, initsubplan);
1836
initExtParam = bms_add_members(initExtParam, initplan->extParam);
1837
foreach(l2, initsubplan->setParam)
1839
initSetParam = bms_add_member(initSetParam, lfirst_int(l2));
1841
initplan_cost += initsubplan->startup_cost + initsubplan->per_call_cost;
1845
* Now determine the set of params that are validly referenceable in this
1846
* query level; to wit, those available from outer query levels plus the
1847
* output parameters of any initPlans. (We do not include output
1848
* parameters of regular subplans. Those should only appear within the
1849
* testexpr of SubPlan nodes, and are taken care of locally within
1850
* finalize_primnode. Likewise, special parameters that are generated by
1851
* nodes such as ModifyTable are handled within finalize_plan.)
1853
* Note: this is a bit overly generous since some parameters of upper
1854
* query levels might belong to query subtrees that don't include this
1855
* query, or might be nestloop params that won't be passed down at all.
1856
* However, valid_params is only a debugging crosscheck, so it doesn't
1857
* seem worth expending lots of cycles to try to be exact.
1859
valid_params = bms_copy(initSetParam);
1861
foreach(l, root->glob->paramlist)
1863
PlannerParamItem *pitem = (PlannerParamItem *) lfirst(l);
1865
if (pitem->abslevel < root->query_level)
1867
/* valid outer-level parameter */
1868
valid_params = bms_add_member(valid_params, paramid);
1875
* Now recurse through plan tree.
1877
(void) finalize_plan(root, plan, valid_params, NULL);
1879
bms_free(valid_params);
1882
* Finally, attach any initPlans to the topmost plan node, and add their
1883
* extParams to the topmost node's, too. However, any setParams of the
1884
* initPlans should not be present in the topmost node's extParams, only
1885
* in its allParams. (As of PG 8.1, it's possible that some initPlans
1886
* have extParams that are setParams of other initPlans, so we have to
1887
* take care of this situation explicitly.)
1889
* We also add the eval cost of each initPlan to the startup cost of the
1890
* top node. This is a conservative overestimate, since in fact each
1891
* initPlan might be executed later than plan startup, or even not at all.
1893
if (attach_initplans)
1895
plan->initPlan = root->init_plans;
1896
root->init_plans = NIL; /* make sure they're not attached twice */
1898
/* allParam must include all these params */
1899
plan->allParam = bms_add_members(plan->allParam, initExtParam);
1900
plan->allParam = bms_add_members(plan->allParam, initSetParam);
1901
/* extParam must include any child extParam */
1902
plan->extParam = bms_add_members(plan->extParam, initExtParam);
1903
/* but extParam shouldn't include any setParams */
1904
plan->extParam = bms_del_members(plan->extParam, initSetParam);
1905
/* ensure extParam is exactly NULL if it's empty */
1906
if (bms_is_empty(plan->extParam))
1907
plan->extParam = NULL;
1909
plan->startup_cost += initplan_cost;
1910
plan->total_cost += initplan_cost;
1915
* Recursive processing of all nodes in the plan tree
1917
* valid_params is the set of param IDs considered valid to reference in
1918
* this plan node or its children.
1919
* scan_params is a set of param IDs to force scan plan nodes to reference.
1920
* This is for EvalPlanQual support, and is always NULL at the top of the
1923
* The return value is the computed allParam set for the given Plan node.
1924
* This is just an internal notational convenience.
1927
finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params,
1928
Bitmapset *scan_params)
1930
finalize_primnode_context context;
1931
int locally_added_param;
1932
Bitmapset *nestloop_params;
1933
Bitmapset *child_params;
1938
context.root = root;
1939
context.paramids = NULL; /* initialize set to empty */
1940
locally_added_param = -1; /* there isn't one */
1941
nestloop_params = NULL; /* there aren't any */
1944
* When we call finalize_primnode, context.paramids sets are automatically
1945
* merged together. But when recursing to self, we have to do it the hard
1946
* way. We want the paramids set to include params in subplans as well as
1950
/* Find params in targetlist and qual */
1951
finalize_primnode((Node *) plan->targetlist, &context);
1952
finalize_primnode((Node *) plan->qual, &context);
1954
/* Check additional node-type-specific fields */
1955
switch (nodeTag(plan))
1958
finalize_primnode(((Result *) plan)->resconstantqual,
1963
context.paramids = bms_add_members(context.paramids, scan_params);
1967
finalize_primnode((Node *) ((IndexScan *) plan)->indexqual,
1969
finalize_primnode((Node *) ((IndexScan *) plan)->indexorderby,
1973
* we need not look at indexqualorig, since it will have the same
1974
* param references as indexqual. Likewise, we can ignore
1977
context.paramids = bms_add_members(context.paramids, scan_params);
1980
case T_BitmapIndexScan:
1981
finalize_primnode((Node *) ((BitmapIndexScan *) plan)->indexqual,
1985
* we need not look at indexqualorig, since it will have the same
1986
* param references as indexqual.
1990
case T_BitmapHeapScan:
1991
finalize_primnode((Node *) ((BitmapHeapScan *) plan)->bitmapqualorig,
1993
context.paramids = bms_add_members(context.paramids, scan_params);
1997
finalize_primnode((Node *) ((TidScan *) plan)->tidquals,
1999
context.paramids = bms_add_members(context.paramids, scan_params);
2002
case T_SubqueryScan:
2005
* In a SubqueryScan, SS_finalize_plan has already been run on the
2006
* subplan by the inner invocation of subquery_planner, so there's
2007
* no need to do it again. Instead, just pull out the subplan's
2008
* extParams list, which represents the params it needs from my
2009
* level and higher levels.
2011
context.paramids = bms_add_members(context.paramids,
2012
((SubqueryScan *) plan)->subplan->extParam);
2013
/* We need scan_params too, though */
2014
context.paramids = bms_add_members(context.paramids, scan_params);
2017
case T_FunctionScan:
2018
finalize_primnode(((FunctionScan *) plan)->funcexpr,
2020
context.paramids = bms_add_members(context.paramids, scan_params);
2024
finalize_primnode((Node *) ((ValuesScan *) plan)->values_lists,
2026
context.paramids = bms_add_members(context.paramids, scan_params);
2032
* You might think we should add the node's cteParam to
2033
* paramids, but we shouldn't because that param is just a
2034
* linkage mechanism for multiple CteScan nodes for the same
2035
* CTE; it is never used for changed-param signaling. What we
2036
* have to do instead is to find the referenced CTE plan and
2037
* incorporate its external paramids, so that the correct
2038
* things will happen if the CTE references outer-level
2039
* variables. See test cases for bug #4902.
2041
int plan_id = ((CteScan *) plan)->ctePlanId;
2044
/* so, do this ... */
2045
if (plan_id < 1 || plan_id > list_length(root->glob->subplans))
2046
elog(ERROR, "could not find plan for CteScan referencing plan ID %d",
2048
cteplan = (Plan *) list_nth(root->glob->subplans, plan_id - 1);
2050
bms_add_members(context.paramids, cteplan->extParam);
2053
/* ... but not this */
2055
bms_add_member(context.paramids,
2056
((CteScan *) plan)->cteParam);
2059
context.paramids = bms_add_members(context.paramids,
2064
case T_WorkTableScan:
2066
bms_add_member(context.paramids,
2067
((WorkTableScan *) plan)->wtParam);
2068
context.paramids = bms_add_members(context.paramids, scan_params);
2072
context.paramids = bms_add_members(context.paramids, scan_params);
2077
ModifyTable *mtplan = (ModifyTable *) plan;
2080
/* Force descendant scan nodes to reference epqParam */
2081
locally_added_param = mtplan->epqParam;
2082
valid_params = bms_add_member(bms_copy(valid_params),
2083
locally_added_param);
2084
scan_params = bms_add_member(bms_copy(scan_params),
2085
locally_added_param);
2086
finalize_primnode((Node *) mtplan->returningLists,
2088
foreach(l, mtplan->plans)
2091
bms_add_members(context.paramids,
2104
foreach(l, ((Append *) plan)->appendplans)
2107
bms_add_members(context.paramids,
2120
foreach(l, ((MergeAppend *) plan)->mergeplans)
2123
bms_add_members(context.paramids,
2136
foreach(l, ((BitmapAnd *) plan)->bitmapplans)
2139
bms_add_members(context.paramids,
2152
foreach(l, ((BitmapOr *) plan)->bitmapplans)
2155
bms_add_members(context.paramids,
2168
finalize_primnode((Node *) ((Join *) plan)->joinqual,
2170
/* collect set of params that will be passed to right child */
2171
foreach(l, ((NestLoop *) plan)->nestParams)
2173
NestLoopParam *nlp = (NestLoopParam *) lfirst(l);
2175
nestloop_params = bms_add_member(nestloop_params,
2182
finalize_primnode((Node *) ((Join *) plan)->joinqual,
2184
finalize_primnode((Node *) ((MergeJoin *) plan)->mergeclauses,
2189
finalize_primnode((Node *) ((Join *) plan)->joinqual,
2191
finalize_primnode((Node *) ((HashJoin *) plan)->hashclauses,
2196
finalize_primnode(((Limit *) plan)->limitOffset,
2198
finalize_primnode(((Limit *) plan)->limitCount,
2202
case T_RecursiveUnion:
2203
/* child nodes are allowed to reference wtParam */
2204
locally_added_param = ((RecursiveUnion *) plan)->wtParam;
2205
valid_params = bms_add_member(bms_copy(valid_params),
2206
locally_added_param);
2207
/* wtParam does *not* get added to scan_params */
2211
/* Force descendant scan nodes to reference epqParam */
2212
locally_added_param = ((LockRows *) plan)->epqParam;
2213
valid_params = bms_add_member(bms_copy(valid_params),
2214
locally_added_param);
2215
scan_params = bms_add_member(bms_copy(scan_params),
2216
locally_added_param);
2220
finalize_primnode(((WindowAgg *) plan)->startOffset,
2222
finalize_primnode(((WindowAgg *) plan)->endOffset,
2236
elog(ERROR, "unrecognized node type: %d",
2237
(int) nodeTag(plan));
2240
/* Process left and right child plans, if any */
2241
child_params = finalize_plan(root,
2245
context.paramids = bms_add_members(context.paramids, child_params);
2247
if (nestloop_params)
2249
/* right child can reference nestloop_params as well as valid_params */
2250
child_params = finalize_plan(root,
2252
bms_union(nestloop_params, valid_params),
2254
/* ... and they don't count as parameters used at my level */
2255
child_params = bms_difference(child_params, nestloop_params);
2256
bms_free(nestloop_params);
2261
child_params = finalize_plan(root,
2266
context.paramids = bms_add_members(context.paramids, child_params);
2269
* Any locally generated parameter doesn't count towards its generating
2270
* plan node's external dependencies. (Note: if we changed valid_params
2271
* and/or scan_params, we leak those bitmapsets; not worth the notational
2272
* trouble to clean them up.)
2274
if (locally_added_param >= 0)
2276
context.paramids = bms_del_member(context.paramids,
2277
locally_added_param);
2280
/* Now we have all the paramids */
2282
if (!bms_is_subset(context.paramids, valid_params))
2283
elog(ERROR, "plan should not reference subplan's variable");
2286
* Note: by definition, extParam and allParam should have the same value
2287
* in any plan node that doesn't have child initPlans. We set them equal
2288
* here, and later SS_finalize_plan will update them properly in node(s)
2289
* that it attaches initPlans to.
2291
* For speed at execution time, make sure extParam/allParam are actually
2292
* NULL if they are empty sets.
2294
if (bms_is_empty(context.paramids))
2296
plan->extParam = NULL;
2297
plan->allParam = NULL;
2301
plan->extParam = context.paramids;
2302
plan->allParam = bms_copy(context.paramids);
2305
return plan->allParam;
2309
* finalize_primnode: add IDs of all PARAM_EXEC params appearing in the given
2310
* expression tree to the result set.
2313
finalize_primnode(Node *node, finalize_primnode_context *context)
2317
if (IsA(node, Param))
2319
if (((Param *) node)->paramkind == PARAM_EXEC)
2321
int paramid = ((Param *) node)->paramid;
2323
context->paramids = bms_add_member(context->paramids, paramid);
2325
return false; /* no more to do here */
2327
if (IsA(node, SubPlan))
2329
SubPlan *subplan = (SubPlan *) node;
2330
Plan *plan = planner_subplan_get_plan(context->root, subplan);
2332
Bitmapset *subparamids;
2334
/* Recurse into the testexpr, but not into the Plan */
2335
finalize_primnode(subplan->testexpr, context);
2338
* Remove any param IDs of output parameters of the subplan that were
2339
* referenced in the testexpr. These are not interesting for
2340
* parameter change signaling since we always re-evaluate the subplan.
2341
* Note that this wouldn't work too well if there might be uses of the
2342
* same param IDs elsewhere in the plan, but that can't happen because
2343
* generate_new_param never tries to merge params.
2345
foreach(lc, subplan->paramIds)
2347
context->paramids = bms_del_member(context->paramids,
2351
/* Also examine args list */
2352
finalize_primnode((Node *) subplan->args, context);
2355
* Add params needed by the subplan to paramids, but excluding those
2356
* we will pass down to it.
2358
subparamids = bms_copy(plan->extParam);
2359
foreach(lc, subplan->parParam)
2361
subparamids = bms_del_member(subparamids, lfirst_int(lc));
2363
context->paramids = bms_join(context->paramids, subparamids);
2365
return false; /* no more to do here */
2367
return expression_tree_walker(node, finalize_primnode,
2372
* SS_make_initplan_from_plan - given a plan tree, make it an InitPlan
2374
* The plan is expected to return a scalar value of the given type/collation.
2375
* We build an EXPR_SUBLINK SubPlan node and put it into the initplan
2376
* list for the current query level. A Param that represents the initplan's
2377
* output is returned.
2379
* We assume the plan hasn't been put through SS_finalize_plan.
2382
SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan,
2383
Oid resulttype, int32 resulttypmod,
2384
Oid resultcollation)
2390
* We must run SS_finalize_plan(), since that's normally done before a
2391
* subplan gets put into the initplan list. Tell it not to attach any
2392
* pre-existing initplans to this one, since they are siblings not
2393
* children of this initplan. (This is something else that could perhaps
2394
* be cleaner if we did extParam/allParam processing in setrefs.c instead
2395
* of here? See notes for materialize_finished_plan.)
2399
* Build extParam/allParam sets for plan nodes.
2401
SS_finalize_plan(root, plan, false);
2404
* Add the subplan and its rtable to the global lists.
2406
root->glob->subplans = lappend(root->glob->subplans,
2408
root->glob->subrtables = lappend(root->glob->subrtables,
2409
root->parse->rtable);
2410
root->glob->subrowmarks = lappend(root->glob->subrowmarks,
2414
* Create a SubPlan node and add it to the outer list of InitPlans. Note
2415
* it has to appear after any other InitPlans it might depend on (see
2416
* comments in ExecReScan).
2418
node = makeNode(SubPlan);
2419
node->subLinkType = EXPR_SUBLINK;
2420
get_first_col_type(plan, &node->firstColType, &node->firstColTypmod,
2421
&node->firstColCollation);
2422
node->plan_id = list_length(root->glob->subplans);
2424
root->init_plans = lappend(root->init_plans, node);
2427
* The node can't have any inputs (since it's an initplan), so the
2428
* parParam and args lists remain empty.
2431
cost_subplan(root, node, plan);
2434
* Make a Param that will be the subplan's output.
2436
prm = generate_new_param(root, resulttype, resulttypmod, resultcollation);
2437
node->setParam = list_make1_int(prm->paramid);
2439
/* Label the subplan for EXPLAIN purposes */
2440
node->plan_name = palloc(64);
2441
sprintf(node->plan_name, "InitPlan %d (returns $%d)",
2442
node->plan_id, prm->paramid);
added
removed
src/backend/optimizer/plan/subselect.c
