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postgres/src/backend/optimizer/plan/subselect.c
Tom Lane e1a11d9311 Use FLEXIBLE_ARRAY_MEMBER for HeapTupleHeaderData.t_bits[]. 
This requires changing quite a few places that were depending on
sizeof(HeapTupleHeaderData), but it seems for the best.

Michael Paquier, some adjustments by me
2015-02-21 15:13:06 -05:00

2692 lines
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/*-------------------------------------------------------------------------
*
* 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/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 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, &paramIds);
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;
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;
/*
* 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(NULL,
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, 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->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);
}
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_finalize_plan - do final sublink and parameter processing for a
* completed Plan.
*
* This recursively computes the extParam and allParam sets for every Plan
* node in the given plan tree. It also optionally attaches any previously
* generated InitPlans to the top plan node. (Any InitPlans should already
* have been put through SS_finalize_plan.)
*/
void
SS_finalize_plan(PlannerInfo *root, Plan *plan, bool attach_initplans)
{
Bitmapset *valid_params,
*initExtParam,
*initSetParam;
Cost initplan_cost;
PlannerInfo *proot;
ListCell *l;
/*
* Examine any initPlans to determine the set of external params they
* reference, the set of output params they supply, and their total cost.
* We'll use at least some of this info below. (Note we are assuming that
* finalize_plan doesn't touch the initPlans.)
*
* In the case where attach_initplans is false, we are assuming that the
* existing initPlans are siblings that might supply params needed by the
* current plan.
*/
initExtParam = initSetParam = NULL;
initplan_cost = 0;
foreach(l, root->init_plans)
{
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));
}
initplan_cost += initsubplan->startup_cost + initsubplan->per_call_cost;
}
/*
* Now determine the set of params that are validly referenceable in this
* query level; to wit, those available from outer query levels plus the
* output parameters of any local initPlans. (We do not include output
* parameters of regular subplans. Those should only appear within the
* testexpr of SubPlan nodes, and are taken care of locally within
* finalize_primnode. Likewise, special parameters that are generated by
* nodes such as ModifyTable are handled within finalize_plan.)
*/
valid_params = bms_copy(initSetParam);
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);
valid_params = bms_add_member(valid_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)
{
valid_params = bms_add_member(valid_params, lfirst_int(l2));
}
}
/* Include worktable ID, if a recursive query is being planned */
if (proot->wt_param_id >= 0)
valid_params = bms_add_member(valid_params, proot->wt_param_id);
}
/*
* Now recurse through plan tree.
*/
(void) finalize_plan(root, plan, valid_params, NULL);
bms_free(valid_params);
/*
* Finally, attach any initPlans to the topmost plan node, and add their
* extParams to the topmost node's, too. However, any setParams of the
* initPlans should not be present in the topmost node's extParams, only
* in its allParams. (As of PG 8.1, it's possible that some initPlans
* have extParams that are setParams of other initPlans, so we have to
* take care of this situation explicitly.)
*
* We also add the eval cost of each initPlan to the startup cost of the
* top node. This is a conservative overestimate, since in fact each
* initPlan might be executed later than plan startup, or even not at all.
*/
if (attach_initplans)
{
plan->initPlan = root->init_plans;
root->init_plans = NIL; /* make sure they're not attached twice */
/* allParam must include all these params */
plan->allParam = bms_add_members(plan->allParam, initExtParam);
plan->allParam = bms_add_members(plan->allParam, initSetParam);
/* extParam must include any child extParam */
plan->extParam = bms_add_members(plan->extParam, initExtParam);
/* but extParam shouldn't include any setParams */
plan->extParam = bms_del_members(plan->extParam, initSetParam);
/* ensure extParam is exactly NULL if it's empty */
if (bms_is_empty(plan->extParam))
plan->extParam = NULL;
plan->startup_cost += initplan_cost;
plan->total_cost += initplan_cost;
}
}
/*
* Recursive processing of all nodes in the plan tree
*
* valid_params is the set of param IDs considered 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.
*/
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 *child_params;
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 */
/*
* 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_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:
/*
* In a SubqueryScan, SS_finalize_plan has already been run on the
* subplan by the inner invocation of subquery_planner, so there's
* no need to do it again. Instead, just pull out the subplan's
* extParams list, which represents the params it needs from my
* level and higher levels.
*/
context.paramids = bms_add_members(context.paramids,
((SubqueryScan *) plan)->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.
*/
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);
context.paramids = bms_add_members(context.paramids, scan_params);
break;
case T_CustomScan:
finalize_primnode((Node *) ((CustomScan *) plan)->custom_exprs,
&context);
context.paramids = bms_add_members(context.paramids, 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);
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_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 */
if (!bms_is_subset(context.paramids, valid_params))
elog(ERROR, "plan should not reference subplan's variable");
/*
* Note: by definition, extParam and allParam should have the same value
* in any plan node that doesn't have child initPlans. We set them equal
* here, and later SS_finalize_plan will update them properly in node(s)
* that it attaches initPlans to.
*
* For speed at execution time, make sure extParam/allParam are actually
* NULL if they are empty sets.
*/
if (bms_is_empty(context.paramids))
{
plan->extParam = NULL;
plan->allParam = NULL;
}
else
{
plan->extParam = context.paramids;
plan->allParam = bms_copy(context.paramids);
}
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.
*/
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 current query level. A Param that represents the initplan's
* output is returned.
*
* We assume the plan hasn't been put through SS_finalize_plan.
*/
Param *
SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan,
Oid resulttype, int32 resulttypmod,
Oid resultcollation)
{
SubPlan *node;
Param *prm;
/*
* We must run SS_finalize_plan(), since that's normally done before a
* subplan gets put into the initplan list. Tell it not to attach any
* pre-existing initplans to this one, since they are siblings not
* children of this initplan. (This is something else that could perhaps
* be cleaner if we did extParam/allParam processing in setrefs.c instead
* of here? See notes for materialize_finished_plan.)
*/
/*
* Build extParam/allParam sets for plan nodes.
*/
SS_finalize_plan(root, plan, 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, root);
/*
* 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(root, 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;
}
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