diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c
index 55311058e59..4c076722def 100644
--- a/src/backend/optimizer/plan/planmain.c
+++ b/src/backend/optimizer/plan/planmain.c
@@ -176,7 +176,7 @@ query_planner(PlannerInfo *root, List *tlist,
*/
build_base_rel_tlists(root, tlist);
- find_placeholders_in_jointree(root);
+ find_placeholders_in_query(root);
joinlist = deconstruct_jointree(root);
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index aeaae8c8d87..8bb011b7116 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -784,22 +784,15 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext);
/*
- * Replace references in the translated_vars lists of appendrels. When
- * pulling up an appendrel member, we do not need PHVs in the list of the
- * parent appendrel --- there isn't any outer join between. Elsewhere, use
- * PHVs for safety. (This analysis could be made tighter but it seems
- * unlikely to be worth much trouble.)
+ * Replace references in the translated_vars lists of appendrels, too.
+ * We do it this way because we must preserve the AppendRelInfo structs.
*/
foreach(lc, root->append_rel_list)
{
AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(lc);
- bool save_need_phvs = rvcontext.need_phvs;
- if (appinfo == containing_appendrel)
- rvcontext.need_phvs = false;
appinfo->translated_vars = (List *)
pullup_replace_vars((Node *) appinfo->translated_vars, &rvcontext);
- rvcontext.need_phvs = save_need_phvs;
}
/*
@@ -1407,14 +1400,31 @@ pullup_replace_vars_callback(Var *var,
if (newnode && IsA(newnode, Var) &&
((Var *) newnode)->varlevelsup == 0)
{
- /* Simple Vars always escape being wrapped */
- wrap = false;
+ /*
+ * Simple Vars normally escape being wrapped. However, in
+ * wrap_non_vars mode (ie, we are dealing with an appendrel
+ * member), we must ensure that each tlist entry expands to a
+ * distinct expression, else we may have problems with
+ * improperly placing identical entries into different
+ * EquivalenceClasses. Therefore, we wrap a Var in a
+ * PlaceHolderVar if it duplicates any earlier entry in the
+ * tlist (ie, we've got "SELECT x, x, ..."). Since each PHV
+ * is distinct, this fixes the ambiguity. We can use
+ * tlist_member to detect whether there's an earlier
+ * duplicate.
+ */
+ wrap = (rcon->wrap_non_vars &&
+ tlist_member(newnode, rcon->targetlist) != tle);
}
else if (newnode && IsA(newnode, PlaceHolderVar) &&
((PlaceHolderVar *) newnode)->phlevelsup == 0)
{
- /* No need to wrap a PlaceHolderVar with another one, either */
- wrap = false;
+ /*
+ * No need to directly wrap a PlaceHolderVar with another one,
+ * either, unless we need to prevent duplication.
+ */
+ wrap = (rcon->wrap_non_vars &&
+ tlist_member(newnode, rcon->targetlist) != tle);
}
else if (rcon->wrap_non_vars)
{
diff --git a/src/backend/optimizer/util/placeholder.c b/src/backend/optimizer/util/placeholder.c
index 8b65245b510..3ae5154684d 100644
--- a/src/backend/optimizer/util/placeholder.c
+++ b/src/backend/optimizer/util/placeholder.c
@@ -104,28 +104,41 @@ find_placeholder_info(PlannerInfo *root, PlaceHolderVar *phv,
}
/*
- * find_placeholders_in_jointree
- * Search the jointree for PlaceHolderVars, and build PlaceHolderInfos
+ * find_placeholders_in_query
+ * Search the query for PlaceHolderVars, and build PlaceHolderInfos
*
- * We don't need to look at the targetlist because build_base_rel_tlists()
- * will already have made entries for any PHVs in the tlist.
+ * We need to examine the jointree, but not the targetlist, because
+ * build_base_rel_tlists() will already have made entries for any PHVs
+ * in the targetlist.
+ *
+ * We also need to search for PHVs in AppendRelInfo translated_vars
+ * lists. In most cases, translated_vars entries aren't directly referenced
+ * elsewhere, but we need to create PlaceHolderInfo entries for them to
+ * support set_rel_width() calculations for the appendrel child relations.
*/
void
-find_placeholders_in_jointree(PlannerInfo *root)
+find_placeholders_in_query(PlannerInfo *root)
{
/* We need do nothing if the query contains no PlaceHolderVars */
if (root->glob->lastPHId != 0)
{
- /* Start recursion at top of jointree */
+ /* Recursively search the jointree */
Assert(root->parse->jointree != NULL &&
IsA(root->parse->jointree, FromExpr));
(void) find_placeholders_recurse(root, (Node *) root->parse->jointree);
+
+ /*
+ * Also search the append_rel_list for translated vars that are PHVs.
+ * Barring finding them elsewhere in the query, they do not need any
+ * ph_may_need bits, only to be present in the PlaceHolderInfo list.
+ */
+ mark_placeholders_in_expr(root, (Node *) root->append_rel_list, NULL);
}
}
/*
* find_placeholders_recurse
- * One recursion level of find_placeholders_in_jointree.
+ * One recursion level of jointree search for find_placeholders_in_query.
*
* jtnode is the current jointree node to examine.
*
diff --git a/src/include/optimizer/placeholder.h b/src/include/optimizer/placeholder.h
index f112419fd58..5fbebfcb0c8 100644
--- a/src/include/optimizer/placeholder.h
+++ b/src/include/optimizer/placeholder.h
@@ -21,7 +21,7 @@ extern PlaceHolderVar *make_placeholder_expr(PlannerInfo *root, Expr *expr,
Relids phrels);
extern PlaceHolderInfo *find_placeholder_info(PlannerInfo *root,
PlaceHolderVar *phv, bool create_new_ph);
-extern void find_placeholders_in_jointree(PlannerInfo *root);
+extern void find_placeholders_in_query(PlannerInfo *root);
extern void mark_placeholder_maybe_needed(PlannerInfo *root,
PlaceHolderInfo *phinfo, Relids relids);
extern void update_placeholder_eval_levels(PlannerInfo *root,
diff --git a/src/test/regress/expected/inherit.out b/src/test/regress/expected/inherit.out
index 0948974d9ad..3e2ab9ac5b8 100644
--- a/src/test/regress/expected/inherit.out
+++ b/src/test/regress/expected/inherit.out
@@ -1242,3 +1242,61 @@ NOTICE: drop cascades to 3 other objects
DETAIL: drop cascades to table matest1
drop cascades to table matest2
drop cascades to table matest3
+--
+-- Test merge-append for UNION ALL append relations
+-- Check handling of duplicated, constant, or volatile targetlist items
+--
+set enable_seqscan = off;
+set enable_indexscan = on;
+set enable_bitmapscan = off;
+explain (costs off)
+SELECT thousand, tenthous FROM tenk1
+UNION ALL
+SELECT thousand, thousand FROM tenk1
+ORDER BY thousand, tenthous;
+ QUERY PLAN
+-----------------------------------------------------------------------
+ Result
+ -> Merge Append
+ Sort Key: public.tenk1.thousand, public.tenk1.tenthous
+ -> Index Only Scan using tenk1_thous_tenthous on tenk1
+ -> Sort
+ Sort Key: public.tenk1.thousand, public.tenk1.thousand
+ -> Index Only Scan using tenk1_thous_tenthous on tenk1
+(7 rows)
+
+explain (costs off)
+SELECT thousand, tenthous FROM tenk1
+UNION ALL
+SELECT 42, 42 FROM tenk1
+ORDER BY thousand, tenthous;
+ QUERY PLAN
+-----------------------------------------------------------------------
+ Result
+ -> Merge Append
+ Sort Key: public.tenk1.thousand, public.tenk1.tenthous
+ -> Index Only Scan using tenk1_thous_tenthous on tenk1
+ -> Sort
+ Sort Key: (42), (42)
+ -> Index Only Scan using tenk1_thous_tenthous on tenk1
+(7 rows)
+
+explain (costs off)
+SELECT thousand, tenthous FROM tenk1
+UNION ALL
+SELECT thousand, random()::integer FROM tenk1
+ORDER BY thousand, tenthous;
+ QUERY PLAN
+-----------------------------------------------------------------------
+ Result
+ -> Merge Append
+ Sort Key: public.tenk1.thousand, public.tenk1.tenthous
+ -> Index Only Scan using tenk1_thous_tenthous on tenk1
+ -> Sort
+ Sort Key: public.tenk1.thousand, ((random())::integer)
+ -> Index Only Scan using tenk1_thous_tenthous on tenk1
+(7 rows)
+
+reset enable_seqscan;
+reset enable_indexscan;
+reset enable_bitmapscan;
diff --git a/src/test/regress/sql/inherit.sql b/src/test/regress/sql/inherit.sql
index 3087a14b729..6e5a1d1c8ee 100644
--- a/src/test/regress/sql/inherit.sql
+++ b/src/test/regress/sql/inherit.sql
@@ -406,3 +406,34 @@ select * from matest0 order by 1-id;
reset enable_seqscan;
drop table matest0 cascade;
+
+--
+-- Test merge-append for UNION ALL append relations
+-- Check handling of duplicated, constant, or volatile targetlist items
+--
+
+set enable_seqscan = off;
+set enable_indexscan = on;
+set enable_bitmapscan = off;
+
+explain (costs off)
+SELECT thousand, tenthous FROM tenk1
+UNION ALL
+SELECT thousand, thousand FROM tenk1
+ORDER BY thousand, tenthous;
+
+explain (costs off)
+SELECT thousand, tenthous FROM tenk1
+UNION ALL
+SELECT 42, 42 FROM tenk1
+ORDER BY thousand, tenthous;
+
+explain (costs off)
+SELECT thousand, tenthous FROM tenk1
+UNION ALL
+SELECT thousand, random()::integer FROM tenk1
+ORDER BY thousand, tenthous;
+
+reset enable_seqscan;
+reset enable_indexscan;
+reset enable_bitmapscan;