From 1d97c19a0f748e94b9582dcbaec33ad74be062f9 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 19 Apr 2009 19:46:33 +0000
Subject: [PATCH] Fix estimate_num_groups() to not fail on PlaceHolderVars, per
report from Stefan Kaltenbrunner. The most reasonable behavior (at least for
the near term) seems to be to ignore the PlaceHolderVar and examine its
argument instead. In support of this, change the API of pull_var_clause() to
allow callers to request recursion into PlaceHolderVars. Currently
estimate_num_groups() is the only customer for that behavior, but where
there's one there may be others.
---
src/backend/catalog/heap.c | 6 ++--
src/backend/optimizer/path/allpaths.c | 4 +--
src/backend/optimizer/path/equivclass.c | 5 ++--
src/backend/optimizer/plan/createplan.c | 5 ++--
src/backend/optimizer/plan/initsplan.c | 7 +++--
src/backend/optimizer/plan/planner.c | 4 +--
src/backend/optimizer/prep/preptlist.c | 5 ++--
src/backend/optimizer/util/placeholder.c | 4 +--
src/backend/optimizer/util/tlist.c | 5 ++--
src/backend/optimizer/util/var.c | 38 +++++++++++++++---------
src/backend/utils/adt/selfuncs.c | 9 ++++--
src/include/optimizer/var.h | 10 +++++--
12 files changed, 63 insertions(+), 39 deletions(-)
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index f6b52109fe9..bc03ef60331 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.352 2009/03/31 17:59:56 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.353 2009/04/19 19:46:32 tgl Exp $
*
*
* INTERFACE ROUTINES
@@ -1621,7 +1621,7 @@ StoreRelCheck(Relation rel, char *ccname, Node *expr,
* in check constraints; it would fail to examine the contents of
* subselects.
*/
- varList = pull_var_clause(expr, false);
+ varList = pull_var_clause(expr, PVC_REJECT_PLACEHOLDERS);
keycount = list_length(varList);
if (keycount > 0)
@@ -1915,7 +1915,7 @@ AddRelationNewConstraints(Relation rel,
List *vars;
char *colname;
- vars = pull_var_clause(expr, false);
+ vars = pull_var_clause(expr, PVC_REJECT_PLACEHOLDERS);
/* eliminate duplicates */
vars = list_union(NIL, vars);
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index a172c5de7ab..fee9b8fac86 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.181 2009/03/10 20:58:26 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.182 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1122,7 +1122,7 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual,
* Examine all Vars used in clause; since it's a restriction clause, all
* such Vars must refer to subselect output columns.
*/
- vars = pull_var_clause(qual, true);
+ vars = pull_var_clause(qual, PVC_INCLUDE_PLACEHOLDERS);
foreach(vl, vars)
{
Var *var = (Var *) lfirst(vl);
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index bc4544e5e06..17c95396797 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -10,7 +10,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.17 2009/02/06 23:43:23 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.18 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -689,7 +689,8 @@ generate_base_implied_equalities_no_const(PlannerInfo *root,
foreach(lc, ec->ec_members)
{
EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
- List *vars = pull_var_clause((Node *) cur_em->em_expr, true);
+ List *vars = pull_var_clause((Node *) cur_em->em_expr,
+ PVC_INCLUDE_PLACEHOLDERS);
add_vars_to_targetlist(root, vars, ec->ec_relids);
list_free(vars);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index cff0424c6c7..1a957ac3969 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.257 2009/03/26 17:15:35 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.258 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -3022,7 +3022,8 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
if (em->em_is_const || em->em_is_child)
continue;
sortexpr = em->em_expr;
- exprvars = pull_var_clause((Node *) sortexpr, true);
+ exprvars = pull_var_clause((Node *) sortexpr,
+ PVC_INCLUDE_PLACEHOLDERS);
foreach(k, exprvars)
{
if (!tlist_member_ignore_relabel(lfirst(k), tlist))
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c
index 952fd7649fd..dd73beb759f 100644
--- a/src/backend/optimizer/plan/initsplan.c
+++ b/src/backend/optimizer/plan/initsplan.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.150 2009/04/16 20:42:16 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.151 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -130,7 +130,8 @@ add_base_rels_to_query(PlannerInfo *root, Node *jtnode)
void
build_base_rel_tlists(PlannerInfo *root, List *final_tlist)
{
- List *tlist_vars = pull_var_clause((Node *) final_tlist, true);
+ List *tlist_vars = pull_var_clause((Node *) final_tlist,
+ PVC_INCLUDE_PLACEHOLDERS);
if (tlist_vars != NIL)
{
@@ -981,7 +982,7 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
*/
if (bms_membership(relids) == BMS_MULTIPLE)
{
- List *vars = pull_var_clause(clause, true);
+ List *vars = pull_var_clause(clause, PVC_INCLUDE_PLACEHOLDERS);
add_vars_to_targetlist(root, vars, relids);
list_free(vars);
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index d7a793ba769..bf1142aec09 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.253 2009/03/30 17:30:44 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.254 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2236,7 +2236,7 @@ make_subplanTargetList(PlannerInfo *root,
* and window specifications.
*/
sub_tlist = flatten_tlist(tlist);
- extravars = pull_var_clause(parse->havingQual, true);
+ extravars = pull_var_clause(parse->havingQual, PVC_INCLUDE_PLACEHOLDERS);
sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
list_free(extravars);
*need_tlist_eval = false; /* only eval if not flat tlist */
diff --git a/src/backend/optimizer/prep/preptlist.c b/src/backend/optimizer/prep/preptlist.c
index e6bd43f7b3a..73a158e5d89 100644
--- a/src/backend/optimizer/prep/preptlist.c
+++ b/src/backend/optimizer/prep/preptlist.c
@@ -16,7 +16,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/prep/preptlist.c,v 1.95 2009/01/01 17:23:44 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/prep/preptlist.c,v 1.96 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -193,7 +193,8 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
List *vars;
ListCell *l;
- vars = pull_var_clause((Node *) parse->returningList, true);
+ vars = pull_var_clause((Node *) parse->returningList,
+ PVC_INCLUDE_PLACEHOLDERS);
foreach(l, vars)
{
Var *var = (Var *) lfirst(l);
diff --git a/src/backend/optimizer/util/placeholder.c b/src/backend/optimizer/util/placeholder.c
index c1834a12914..019352158d2 100644
--- a/src/backend/optimizer/util/placeholder.c
+++ b/src/backend/optimizer/util/placeholder.c
@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/util/placeholder.c,v 1.3 2009/01/01 17:23:45 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/util/placeholder.c,v 1.4 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -162,7 +162,7 @@ fix_placeholder_eval_levels(PlannerInfo *root)
if (bms_membership(eval_at) == BMS_MULTIPLE)
{
List *vars = pull_var_clause((Node *) phinfo->ph_var->phexpr,
- true);
+ PVC_INCLUDE_PLACEHOLDERS);
add_vars_to_targetlist(root, vars, eval_at);
list_free(vars);
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 5cf2839b37e..9526aefd9ac 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/util/tlist.c,v 1.85 2009/01/01 17:23:45 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/util/tlist.c,v 1.86 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -91,7 +91,8 @@ tlist_member_ignore_relabel(Node *node, List *targetlist)
List *
flatten_tlist(List *tlist)
{
- List *vlist = pull_var_clause((Node *) tlist, true);
+ List *vlist = pull_var_clause((Node *) tlist,
+ PVC_INCLUDE_PLACEHOLDERS);
List *new_tlist;
new_tlist = add_to_flat_tlist(NIL, vlist);
diff --git a/src/backend/optimizer/util/var.c b/src/backend/optimizer/util/var.c
index 7768712b569..cd88c337f1a 100644
--- a/src/backend/optimizer/util/var.c
+++ b/src/backend/optimizer/util/var.c
@@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.84 2009/02/25 03:30:37 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.85 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -56,7 +56,7 @@ typedef struct
typedef struct
{
List *varlist;
- bool includePlaceHolderVars;
+ PVCPlaceHolderBehavior behavior;
} pull_var_clause_context;
typedef struct
@@ -614,11 +614,13 @@ find_minimum_var_level_walker(Node *node,
* pull_var_clause
* Recursively pulls all Var nodes from an expression clause.
*
- * PlaceHolderVars are included too, if includePlaceHolderVars is true.
- * If it isn't true, an error is thrown if any are found.
- * Note that Vars within a PHV's expression are *not* included.
+ * PlaceHolderVars are handled according to 'behavior':
+ * PVC_REJECT_PLACEHOLDERS throw error if PlaceHolderVar found
+ * PVC_INCLUDE_PLACEHOLDERS include PlaceHolderVars in output list
+ * PVC_RECURSE_PLACEHOLDERS recurse into PlaceHolderVar argument
+ * Vars within a PHV's expression are included only in the last case.
*
- * CurrentOfExpr nodes are *not* included.
+ * CurrentOfExpr nodes are ignored in all cases.
*
* Upper-level vars (with varlevelsup > 0) are not included.
* (These probably represent errors too, but we don't complain.)
@@ -630,12 +632,12 @@ find_minimum_var_level_walker(Node *node,
* of sublinks to subplans!
*/
List *
-pull_var_clause(Node *node, bool includePlaceHolderVars)
+pull_var_clause(Node *node, PVCPlaceHolderBehavior behavior)
{
pull_var_clause_context context;
context.varlist = NIL;
- context.includePlaceHolderVars = includePlaceHolderVars;
+ context.behavior = behavior;
pull_var_clause_walker(node, &context);
return context.varlist;
@@ -654,12 +656,20 @@ pull_var_clause_walker(Node *node, pull_var_clause_context *context)
}
if (IsA(node, PlaceHolderVar))
{
- if (!context->includePlaceHolderVars)
- elog(ERROR, "PlaceHolderVar found where not expected");
- if (((PlaceHolderVar *) node)->phlevelsup == 0)
- context->varlist = lappend(context->varlist, node);
- /* we do NOT descend into the contained expression */
- return false;
+ switch (context->behavior)
+ {
+ case PVC_REJECT_PLACEHOLDERS:
+ elog(ERROR, "PlaceHolderVar found where not expected");
+ break;
+ case PVC_INCLUDE_PLACEHOLDERS:
+ if (((PlaceHolderVar *) node)->phlevelsup == 0)
+ context->varlist = lappend(context->varlist, node);
+ /* we do NOT descend into the contained expression */
+ return false;
+ case PVC_RECURSE_PLACEHOLDERS:
+ /* ignore the placeholder, look at its argument instead */
+ break;
+ }
}
return expression_tree_walker(node, pull_var_clause_walker,
(void *) context);
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index e4b1acb1f83..3f07db6857f 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.259 2009/02/15 20:16:21 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.260 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2984,9 +2984,12 @@ estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows)
ReleaseVariableStats(vardata);
/*
- * Else pull out the component Vars
+ * Else pull out the component Vars. Handle PlaceHolderVars by
+ * recursing into their arguments (effectively assuming that the
+ * PlaceHolderVar doesn't change the number of groups, which boils
+ * down to ignoring the possible addition of nulls to the result set).
*/
- varshere = pull_var_clause(groupexpr, true);
+ varshere = pull_var_clause(groupexpr, PVC_RECURSE_PLACEHOLDERS);
/*
* If we find any variable-free GROUP BY item, then either it is a
diff --git a/src/include/optimizer/var.h b/src/include/optimizer/var.h
index 83b181932e5..5d19572e0d9 100644
--- a/src/include/optimizer/var.h
+++ b/src/include/optimizer/var.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/optimizer/var.h,v 1.40 2009/01/01 17:24:00 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/var.h,v 1.41 2009/04/19 19:46:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -16,6 +16,12 @@
#include "nodes/relation.h"
+typedef enum
+{
+ PVC_REJECT_PLACEHOLDERS, /* throw error if PlaceHolderVar found */
+ PVC_INCLUDE_PLACEHOLDERS, /* include PlaceHolderVars in output list */
+ PVC_RECURSE_PLACEHOLDERS /* recurse into PlaceHolderVar argument */
+} PVCPlaceHolderBehavior;
extern Relids pull_varnos(Node *node);
extern void pull_varattnos(Node *node, Bitmapset **varattnos);
@@ -24,7 +30,7 @@ extern bool contain_vars_of_level(Node *node, int levelsup);
extern int locate_var_of_level(Node *node, int levelsup);
extern int locate_var_of_relation(Node *node, int relid, int levelsup);
extern int find_minimum_var_level(Node *node);
-extern List *pull_var_clause(Node *node, bool includePlaceHolderVars);
+extern List *pull_var_clause(Node *node, PVCPlaceHolderBehavior behavior);
extern Node *flatten_join_alias_vars(PlannerInfo *root, Node *node);
#endif /* VAR_H */
--
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