summaryrefslogtreecommitdiff
path: root/src/backend/optimizer/plan/subselect.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/backend/optimizer/plan/subselect.c')
-rw-r--r--src/backend/optimizer/plan/subselect.c109
1 files changed, 73 insertions, 36 deletions
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 82eb2efceb9..7170d727ef0 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -1,20 +1,24 @@
/*-------------------------------------------------------------------------
*
* subselect.c
+ * Planning routines for subselects and parameters.
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.18 1999/06/21 01:20:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "catalog/pg_type.h"
-
#include "nodes/pg_list.h"
#include "nodes/plannodes.h"
#include "nodes/parsenodes.h"
#include "nodes/relation.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
-
#include "optimizer/subselect.h"
#include "optimizer/planner.h"
#include "optimizer/planmain.h"
@@ -27,12 +31,31 @@
#include "optimizer/cost.h"
int PlannerQueryLevel; /* level of current query */
-List *PlannerVarParam; /* correlation Vars to Param mapper */
-List *PlannerParamVar; /* to get Var from Param->paramid */
List *PlannerInitPlan; /* init subplans for current query */
-int PlannerPlanId;
+List *PlannerParamVar; /* to get Var from Param->paramid */
+int PlannerPlanId; /* to assign unique ID to subquery plans */
+
+/*--------------------
+ * PlannerParamVar is a list of Var nodes, wherein the n'th entry
+ * (n counts from 0) corresponds to Param->paramid = n. The Var nodes
+ * are ordinary except for one thing: their varlevelsup field does NOT
+ * have the usual interpretation of "subplan levels out from current".
+ * Instead, it contains the absolute plan level, with the outermost
+ * plan being level 1 and nested plans having higher level numbers.
+ * This nonstandardness is useful because we don't have to run around
+ * and update the list elements when we enter or exit a subplan
+ * recursion level. But we must pay attention not to confuse this
+ * meaning with the normal meaning of varlevelsup.
+ *--------------------
+ */
+/*
+ * Create a new entry in the PlannerParamVar list, and return its index.
+ *
+ * var contains the data to be copied, except for varlevelsup which
+ * is set from the absolute level value given by varlevel.
+ */
static int
_new_param(Var *var, int varlevel)
{
@@ -61,38 +84,49 @@ _new_param(Var *var, int varlevel)
return i;
}
+/*
+ * Generate a Param node to replace the given Var,
+ * which is expected to have varlevelsup > 0 (ie, it is not local).
+ */
static Param *
_replace_var(Var *var)
{
- List **rt = (List **) nth(var->varlevelsup, PlannerVarParam);
- List *vpe = rt[var->varno - 1];
+ List *ppv;
Param *retval;
+ int varlevel;
int i;
- if (vpe == NULL)
- {
- vpe = rt[var->varno - 1] = makeNode(List);
- lfirsti(vpe) = -1;
- lnext(vpe) = NULL;
- }
+ Assert(var->varlevelsup > 0 && var->varlevelsup < PlannerQueryLevel);
+ varlevel = PlannerQueryLevel - var->varlevelsup;
- for (i = ObjectIdAttributeNumber;; i++)
+ /*
+ * If there's already a PlannerParamVar entry for this same Var,
+ * just use it. NOTE: in situations involving UNION or inheritance,
+ * it is possible for the same varno/varlevel to refer to different RTEs
+ * in different parts of the parsetree, so that different fields might
+ * end up sharing the same Param number. As long as we check the vartype
+ * as well, I believe that this sort of aliasing will cause no trouble.
+ * The correct field should get stored into the Param slot at execution
+ * in each part of the tree.
+ */
+ i = 0;
+ foreach(ppv, PlannerParamVar)
{
- if (i == var->varattno)
+ Var *pvar = lfirst(ppv);
+
+ if (pvar->varno == var->varno &&
+ pvar->varattno == var->varattno &&
+ pvar->varlevelsup == varlevel &&
+ pvar->vartype == var->vartype)
break;
- if (lnext(vpe) == NULL)
- {
- lnext(vpe) = makeNode(List);
- vpe = lnext(vpe);
- lfirsti(vpe) = -1;
- lnext(vpe) = NULL;
- }
- else
- vpe = lnext(vpe);
+ i++;
}
- if ((i = lfirsti(vpe)) < 0) /* parameter is not assigned */
- i = _new_param(var, PlannerQueryLevel - var->varlevelsup);
+ if (! ppv)
+ {
+ /* Nope, so make a new one */
+ i = _new_param(var, varlevel);
+ }
retval = makeNode(Param);
retval->paramkind = PARAM_EXEC;
@@ -125,7 +159,7 @@ _make_subplan(SubLink *slink)
(void) SS_finalize_plan(plan);
plan->initPlan = PlannerInitPlan;
- /* Get extParam from InitPlan-s */
+ /* Create extParam list as union of InitPlan-s' lists */
foreach(lst, PlannerInitPlan)
{
List *lp;
@@ -146,11 +180,12 @@ _make_subplan(SubLink *slink)
node->sublink = slink;
slink->subselect = NULL; /* cool ?! */
- /* make parParam list */
+ /* make parParam list of params coming from current query level */
foreach(lst, plan->extParam)
{
Var *var = nth(lfirsti(lst), PlannerParamVar);
+ /* note varlevelsup is absolute level number */
if (var->varlevelsup == PlannerQueryLevel)
node->parParam = lappendi(node->parParam, lfirsti(lst));
}
@@ -170,7 +205,7 @@ _make_subplan(SubLink *slink)
TargetEntry *te = nth(i, plan->targetlist);
Var *var = makeVar(0, 0, te->resdom->restype,
te->resdom->restypmod,
- PlannerQueryLevel, 0, 0);
+ 0, 0, 0);
Param *prm = makeNode(Param);
prm->paramkind = PARAM_EXEC;
@@ -190,7 +225,7 @@ _make_subplan(SubLink *slink)
}
else if (node->parParam == NULL && slink->subLinkType == EXISTS_SUBLINK)
{
- Var *var = makeVar(0, 0, BOOLOID, -1, PlannerQueryLevel, 0, 0);
+ Var *var = makeVar(0, 0, BOOLOID, -1, 0, 0, 0);
Param *prm = makeNode(Param);
prm->paramkind = PARAM_EXEC;
@@ -202,10 +237,10 @@ _make_subplan(SubLink *slink)
result = (Node *) prm;
}
else
-/* make expression of SUBPLAN type */
{
+ /* make expression of SUBPLAN type */
Expr *expr = makeNode(Expr);
- List *args = NULL;
+ List *args = NIL;
int i = 0;
expr->typeOid = BOOLOID;
@@ -222,6 +257,10 @@ _make_subplan(SubLink *slink)
Var *var = nth(lfirsti(lst), PlannerParamVar);
var = (Var *) copyObject(var);
+ /* Must fix absolute-level varlevelsup from the
+ * PlannerParamVar entry. But since var is at current
+ * subplan level, this is easy:
+ */
var->varlevelsup = 0;
args = lappend(args, var);
}
@@ -240,7 +279,6 @@ _make_subplan(SubLink *slink)
}
return result;
-
}
static List *
@@ -305,6 +343,7 @@ _finalize_primnode(void *expr, List **subplan)
{
Var *var = nth(lfirsti(lst), PlannerParamVar);
+ /* note varlevelsup is absolute level number */
if (var->varlevelsup < PlannerQueryLevel &&
!intMember(lfirsti(lst), result))
result = lappendi(result, lfirsti(lst));
@@ -332,10 +371,7 @@ SS_replace_correlation_vars(Node *expr)
else if (IsA(expr, Var))
{
if (((Var *) expr)->varlevelsup > 0)
- {
- Assert(((Var *) expr)->varlevelsup < PlannerQueryLevel);
expr = (Node *) _replace_var((Var *) expr);
- }
}
else if (IsA(expr, Iter))
((Iter *) expr)->iterexpr = SS_replace_correlation_vars(((Iter *) expr)->iterexpr);
@@ -480,6 +516,7 @@ SS_finalize_plan(Plan *plan)
{
Var *var = nth(lfirsti(lst), PlannerParamVar);
+ /* note varlevelsup is absolute level number */
if (var->varlevelsup < PlannerQueryLevel)
extParam = lappendi(extParam, lfirsti(lst));
else if (var->varlevelsup > PlannerQueryLevel)
generated by cgit v1.2.3 (git 2.46.0) at 2025-09-29 07:46:55 +0000