3 files changed, 40 insertions, 0 deletions
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 0ae5873868b..1a1aebe7b08 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3808,6 +3808,16 @@ find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 {
 	ListCell   *lc;
 
+	/*
+	 * For the moment, never try to share transition states between different
+	 * ordered-set aggregates.  This is necessary because the finalfns of the
+	 * built-in OSAs (see orderedsetaggs.c) are destructive of their
+	 * transition states.  We should fix them so we can allow this, but not
+	 * losing performance in the normal non-shared case will take some work.
+	 */
+	if (AGGKIND_IS_ORDERED_SET(newagg->aggkind))
+		return -1;
+
 	foreach(lc, transnos)
 	{
 		int			transno = lfirst_int(lc);
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index ce6b841a331..82ede655aa9 100644
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -1860,6 +1860,25 @@ NOTICE:  avg_transfn called with 3
       2 |      6
 (1 row)
 
+-- ideally these would share state, but we have to fix the OSAs first.
+select
+  percentile_cont(0.5) within group (order by a),
+  percentile_disc(0.5) within group (order by a)
+from (values(1::float8),(3),(5),(7)) t(a);
+ percentile_cont | percentile_disc 
+-----------------+-----------------
+               4 |               3
+(1 row)
+
+select
+  rank(4) within group (order by a),
+  dense_rank(4) within group (order by a)
+from (values(1),(3),(5),(7)) t(a);
+ rank | dense_rank 
+------+------------
+    3 |          3
+(1 row)
+
 -- test that aggs with the same sfunc and initcond share the same agg state
 create aggregate my_sum_init(int4)
 (
diff --git a/src/test/regress/sql/aggregates.sql b/src/test/regress/sql/aggregates.sql
index 2eeb3eedbdf..77314522eb9 100644
--- a/src/test/regress/sql/aggregates.sql
+++ b/src/test/regress/sql/aggregates.sql
@@ -739,6 +739,17 @@ select my_avg(one) filter (where one > 1),my_sum(one) from (values(1),(3)) t(one
 -- this should not share the state due to different input columns.
 select my_avg(one),my_sum(two) from (values(1,2),(3,4)) t(one,two);
 
+-- ideally these would share state, but we have to fix the OSAs first.
+select
+  percentile_cont(0.5) within group (order by a),
+  percentile_disc(0.5) within group (order by a)
+from (values(1::float8),(3),(5),(7)) t(a);
+
+select
+  rank(4) within group (order by a),
+  dense_rank(4) within group (order by a)
+from (values(1),(3),(5),(7)) t(a);
+
 -- test that aggs with the same sfunc and initcond share the same agg state
 create aggregate my_sum_init(int4)
 (