3 files changed, 56 insertions, 0 deletions
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 6a27ef41400..b019bc1a0d9 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -5722,6 +5722,17 @@ l4:
 			goto out_locked;
 		}
 
+		/*
+		 * Also check Xmin: if this tuple was created by an aborted
+		 * (sub)transaction, then we already locked the last live one in the
+		 * chain, thus we're done, so return success.
+		 */
+		if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(mytup.t_data)))
+		{
+			UnlockReleaseBuffer(buf);
+			return HeapTupleMayBeUpdated;
+		}
+
 		old_infomask = mytup.t_data->t_infomask;
 		old_infomask2 = mytup.t_data->t_infomask2;
 		xmax = HeapTupleHeaderGetRawXmax(mytup.t_data);
diff --git a/src/test/regress/expected/combocid.out b/src/test/regress/expected/combocid.out
index b63894c2837..17eb94a8ffc 100644
--- a/src/test/regress/expected/combocid.out
+++ b/src/test/regress/expected/combocid.out
@@ -140,3 +140,30 @@ SELECT ctid,cmin,* FROM combocidtest;
  (0,6) |    0 |    444
 (3 rows)
 
+-- test for bug reported in
+-- CABRT9RC81YUf1=jsmWopcKJEro=VoeG2ou6sPwyOUTx_qteRsg@mail.gmail.com
+CREATE TABLE IF NOT EXISTS testcase(
+	id int PRIMARY KEY,
+	balance numeric
+);
+INSERT INTO testcase VALUES (1, 0);
+BEGIN;
+SELECT * FROM testcase WHERE testcase.id = 1 FOR UPDATE;
+ id | balance 
+----+---------
+  1 |       0
+(1 row)
+
+UPDATE testcase SET balance = balance + 400 WHERE id=1;
+SAVEPOINT subxact;
+UPDATE testcase SET balance = balance - 100 WHERE id=1;
+ROLLBACK TO SAVEPOINT subxact;
+-- should return one tuple
+SELECT * FROM testcase WHERE id = 1 FOR UPDATE;
+ id | balance 
+----+---------
+  1 |     400
+(1 row)
+
+ROLLBACK;
+DROP TABLE testcase;
diff --git a/src/test/regress/sql/combocid.sql b/src/test/regress/sql/combocid.sql
index f24ac6b01a1..4faea36f41a 100644
--- a/src/test/regress/sql/combocid.sql
+++ b/src/test/regress/sql/combocid.sql
@@ -91,3 +91,21 @@ SELECT ctid,cmin,* FROM combocidtest;
 COMMIT;
 
 SELECT ctid,cmin,* FROM combocidtest;
+
+-- test for bug reported in
+-- CABRT9RC81YUf1=jsmWopcKJEro=VoeG2ou6sPwyOUTx_qteRsg@mail.gmail.com
+CREATE TABLE IF NOT EXISTS testcase(
+	id int PRIMARY KEY,
+	balance numeric
+);
+INSERT INTO testcase VALUES (1, 0);
+BEGIN;
+SELECT * FROM testcase WHERE testcase.id = 1 FOR UPDATE;
+UPDATE testcase SET balance = balance + 400 WHERE id=1;
+SAVEPOINT subxact;
+UPDATE testcase SET balance = balance - 100 WHERE id=1;
+ROLLBACK TO SAVEPOINT subxact;
+-- should return one tuple
+SELECT * FROM testcase WHERE id = 1 FOR UPDATE;
+ROLLBACK;
+DROP TABLE testcase;