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-rw-r--r--src/backend/optimizer/plan/planagg.c23
-rw-r--r--src/backend/optimizer/util/tlist.c37
-rw-r--r--src/include/optimizer/tlist.h3
-rw-r--r--src/test/regress/expected/inherit.out57
-rw-r--r--src/test/regress/sql/inherit.sql4
5 files changed, 123 insertions, 1 deletions
diff --git a/src/backend/optimizer/plan/planagg.c b/src/backend/optimizer/plan/planagg.c
index f7ce9b12a92..88a6c99ea50 100644
--- a/src/backend/optimizer/plan/planagg.c
+++ b/src/backend/optimizer/plan/planagg.c
@@ -37,6 +37,7 @@
#include "optimizer/paths.h"
#include "optimizer/planmain.h"
#include "optimizer/subselect.h"
+#include "optimizer/tlist.h"
#include "parser/parsetree.h"
#include "parser/parse_clause.h"
#include "utils/lsyscache.h"
@@ -521,7 +522,27 @@ make_agg_subplan(PlannerInfo *root, MinMaxAggInfo *mminfo)
*/
plan = create_plan(subroot, mminfo->path);
- plan->targetlist = subparse->targetList;
+ /*
+ * If the top-level plan node is one that cannot do expression evaluation
+ * and its existing target list isn't already what we need, we must insert
+ * a Result node to project the desired tlist.
+ */
+ if (!is_projection_capable_plan(plan) &&
+ !tlist_same_exprs(subparse->targetList, plan->targetlist))
+ {
+ plan = (Plan *) make_result(subroot,
+ subparse->targetList,
+ NULL,
+ plan);
+ }
+ else
+ {
+ /*
+ * Otherwise, just replace the subplan's flat tlist with the desired
+ * tlist.
+ */
+ plan->targetlist = subparse->targetList;
+ }
plan = (Plan *) make_limit(plan,
subparse->limitOffset,
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index b8149f7b461..c98c767f310 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -189,6 +189,43 @@ get_tlist_exprs(List *tlist, bool includeJunk)
/*
+ * tlist_same_exprs
+ * Check whether two target lists contain the same expressions
+ *
+ * Note: this function is used to decide whether it's safe to jam a new tlist
+ * into a non-projection-capable plan node. Obviously we can't do that unless
+ * the node's tlist shows it already returns the column values we want.
+ * However, we can ignore the TargetEntry attributes resname, ressortgroupref,
+ * resorigtbl, resorigcol, and resjunk, because those are only labelings that
+ * don't affect the row values computed by the node. (Moreover, if we didn't
+ * ignore them, we'd frequently fail to make the desired optimization, since
+ * the planner tends to not bother to make resname etc. valid in intermediate
+ * plan nodes.) Note that on success, the caller must still jam the desired
+ * tlist into the plan node, else it won't have the desired labeling fields.
+ */
+bool
+tlist_same_exprs(List *tlist1, List *tlist2)
+{
+ ListCell *lc1,
+ *lc2;
+
+ if (list_length(tlist1) != list_length(tlist2))
+ return false; /* not same length, so can't match */
+
+ forboth(lc1, tlist1, lc2, tlist2)
+ {
+ TargetEntry *tle1 = (TargetEntry *) lfirst(lc1);
+ TargetEntry *tle2 = (TargetEntry *) lfirst(lc2);
+
+ if (!equal(tle1->expr, tle2->expr))
+ return false;
+ }
+
+ return true;
+}
+
+
+/*
* Does tlist have same output datatypes as listed in colTypes?
*
* Resjunk columns are ignored if junkOK is true; otherwise presence of
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index 0edc8835fbd..d172549a332 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -26,6 +26,9 @@ extern List *flatten_tlist(List *tlist, PVCAggregateBehavior aggbehavior,
extern List *add_to_flat_tlist(List *tlist, List *exprs);
extern List *get_tlist_exprs(List *tlist, bool includeJunk);
+
+extern bool tlist_same_exprs(List *tlist1, List *tlist2);
+
extern bool tlist_same_datatypes(List *tlist, List *colTypes, bool junkOK);
extern bool tlist_same_collations(List *tlist, List *colCollations, bool junkOK);
diff --git a/src/test/regress/expected/inherit.out b/src/test/regress/expected/inherit.out
index 36d90f5bba1..c79b8f950f1 100644
--- a/src/test/regress/expected/inherit.out
+++ b/src/test/regress/expected/inherit.out
@@ -1203,6 +1203,28 @@ select * from matest0 order by 1-id;
1 | Test 1
(6 rows)
+explain (verbose, costs off) select min(1-id) from matest0;
+ QUERY PLAN
+------------------------------------------------
+ Aggregate
+ Output: min((1 - public.matest0.id))
+ -> Append
+ -> Seq Scan on public.matest0
+ Output: public.matest0.id
+ -> Seq Scan on public.matest1 matest0
+ Output: public.matest0.id
+ -> Seq Scan on public.matest2 matest0
+ Output: public.matest0.id
+ -> Seq Scan on public.matest3 matest0
+ Output: public.matest0.id
+(11 rows)
+
+select min(1-id) from matest0;
+ min
+-----
+ -5
+(1 row)
+
reset enable_indexscan;
set enable_seqscan = off; -- plan with fewest seqscans should be merge
explain (verbose, costs off) select * from matest0 order by 1-id;
@@ -1236,6 +1258,41 @@ select * from matest0 order by 1-id;
1 | Test 1
(6 rows)
+explain (verbose, costs off) select min(1-id) from matest0;
+ QUERY PLAN
+--------------------------------------------------------------------------------------
+ Result
+ Output: $0
+ InitPlan 1 (returns $0)
+ -> Limit
+ Output: ((1 - public.matest0.id))
+ -> Result
+ Output: ((1 - public.matest0.id))
+ -> Merge Append
+ Sort Key: ((1 - public.matest0.id))
+ -> Index Scan using matest0i on public.matest0
+ Output: public.matest0.id, (1 - public.matest0.id)
+ Index Cond: ((1 - public.matest0.id) IS NOT NULL)
+ -> Index Scan using matest1i on public.matest1 matest0
+ Output: public.matest0.id, (1 - public.matest0.id)
+ Index Cond: ((1 - public.matest0.id) IS NOT NULL)
+ -> Sort
+ Output: public.matest0.id, ((1 - public.matest0.id))
+ Sort Key: ((1 - public.matest0.id))
+ -> Seq Scan on public.matest2 matest0
+ Output: public.matest0.id, (1 - public.matest0.id)
+ Filter: ((1 - public.matest0.id) IS NOT NULL)
+ -> Index Scan using matest3i on public.matest3 matest0
+ Output: public.matest0.id, (1 - public.matest0.id)
+ Index Cond: ((1 - public.matest0.id) IS NOT NULL)
+(24 rows)
+
+select min(1-id) from matest0;
+ min
+-----
+ -5
+(1 row)
+
reset enable_seqscan;
drop table matest0 cascade;
NOTICE: drop cascades to 3 other objects
diff --git a/src/test/regress/sql/inherit.sql b/src/test/regress/sql/inherit.sql
index 6c7d809fb60..3b3d71f040c 100644
--- a/src/test/regress/sql/inherit.sql
+++ b/src/test/regress/sql/inherit.sql
@@ -398,11 +398,15 @@ insert into matest3 (name) values ('Test 6');
set enable_indexscan = off; -- force use of seqscan/sort, so no merge
explain (verbose, costs off) select * from matest0 order by 1-id;
select * from matest0 order by 1-id;
+explain (verbose, costs off) select min(1-id) from matest0;
+select min(1-id) from matest0;
reset enable_indexscan;
set enable_seqscan = off; -- plan with fewest seqscans should be merge
explain (verbose, costs off) select * from matest0 order by 1-id;
select * from matest0 order by 1-id;
+explain (verbose, costs off) select min(1-id) from matest0;
+select min(1-id) from matest0;
reset enable_seqscan;
drop table matest0 cascade;
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-29 18:59:37 +0000