4 files changed, 98 insertions, 5 deletions
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 94eb37d48d2..9756bf98bde 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -9007,6 +9007,10 @@ HeapCheckForSerializableConflictOut(bool visible, Relation relation,
 	 * while it is visible to us.  The "visible" bool indicates whether the
 	 * tuple is visible to us, while HeapTupleSatisfiesVacuum checks what else
 	 * is going on with it.
+	 *
+	 * In the event of a concurrently inserted tuple that also happens to have
+	 * been concurrently updated (by a separate transaction), the xmin of the
+	 * tuple will be used -- not the updater's xid.
 	 */
 	htsvResult = HeapTupleSatisfiesVacuum(tuple, TransactionXmin, buffer);
 	switch (htsvResult)
@@ -9017,17 +9021,24 @@ HeapCheckForSerializableConflictOut(bool visible, Relation relation,
 			xid = HeapTupleHeaderGetXmin(tuple->t_data);
 			break;
 		case HEAPTUPLE_RECENTLY_DEAD:
-			if (!visible)
-				return;
-			xid = HeapTupleHeaderGetUpdateXid(tuple->t_data);
-			break;
 		case HEAPTUPLE_DELETE_IN_PROGRESS:
-			xid = HeapTupleHeaderGetUpdateXid(tuple->t_data);
+			if (visible)
+				xid = HeapTupleHeaderGetUpdateXid(tuple->t_data);
+			else
+				xid = HeapTupleHeaderGetXmin(tuple->t_data);
+
+			if (TransactionIdPrecedes(xid, TransactionXmin))
+			{
+				/* This is like the HEAPTUPLE_DEAD case */
+				Assert(!visible);
+				return;
+			}
 			break;
 		case HEAPTUPLE_INSERT_IN_PROGRESS:
 			xid = HeapTupleHeaderGetXmin(tuple->t_data);
 			break;
 		case HEAPTUPLE_DEAD:
+			Assert(!visible);
 			return;
 		default:
 
diff --git a/src/test/isolation/expected/update-conflict-out.out b/src/test/isolation/expected/update-conflict-out.out
new file mode 100644
index 00000000000..32be3269b32
--- /dev/null
+++ b/src/test/isolation/expected/update-conflict-out.out
@@ -0,0 +1,27 @@
+Parsed test spec with 3 sessions
+
+starting permutation: foo_select bar_insert foo_insert foo_commit trouble_update bar_select bar_commit trouble_abort
+step foo_select: SELECT * FROM txn0 WHERE id = 42;
+id             val            
+
+step bar_insert: INSERT INTO txn0 SELECT 42, 'bar_insert';
+step foo_insert: INSERT INTO txn1 SELECT 7, 'foo_insert';
+step foo_commit: COMMIT;
+step trouble_update: UPDATE txn1 SET val = 'add physical version for "bar_select"' WHERE id = 7;
+step bar_select: SELECT * FROM txn1 WHERE id = 7;
+ERROR:  could not serialize access due to read/write dependencies among transactions
+step bar_commit: COMMIT;
+step trouble_abort: ABORT;
+
+starting permutation: foo_select bar_insert foo_insert foo_commit trouble_delete bar_select bar_commit trouble_abort
+step foo_select: SELECT * FROM txn0 WHERE id = 42;
+id             val            
+
+step bar_insert: INSERT INTO txn0 SELECT 42, 'bar_insert';
+step foo_insert: INSERT INTO txn1 SELECT 7, 'foo_insert';
+step foo_commit: COMMIT;
+step trouble_delete: DELETE FROM txn1 WHERE id = 7;
+step bar_select: SELECT * FROM txn1 WHERE id = 7;
+ERROR:  could not serialize access due to read/write dependencies among transactions
+step bar_commit: COMMIT;
+step trouble_abort: ABORT;
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index 2873cd7c216..218c87b24bf 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -18,6 +18,7 @@ test: two-ids
 test: multiple-row-versions
 test: index-only-scan
 test: predicate-lock-hot-tuple
+test: update-conflict-out
 test: deadlock-simple
 test: deadlock-hard
 test: deadlock-soft
diff --git a/src/test/isolation/specs/update-conflict-out.spec b/src/test/isolation/specs/update-conflict-out.spec
new file mode 100644
index 00000000000..25c27d4ca65
--- /dev/null
+++ b/src/test/isolation/specs/update-conflict-out.spec
@@ -0,0 +1,54 @@
+# Test for interactions between SSI's "conflict out" handling for heapam and
+# concurrently updated tuple
+#
+# See bug report:
+# https://postgr.es/m/db7b729d-0226-d162-a126-8a8ab2dc4443%40jepsen.io
+
+setup
+{
+  CREATE TABLE txn0(id int4 PRIMARY KEY, val TEXT);
+  CREATE TABLE txn1(id int4 PRIMARY KEY, val TEXT);
+}
+
+teardown
+{
+  DROP TABLE txn0;
+  DROP TABLE txn1;
+}
+
+session "foo"
+setup                  { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "foo_select"      { SELECT * FROM txn0 WHERE id = 42; }
+step "foo_insert"      { INSERT INTO txn1 SELECT 7, 'foo_insert'; }
+step "foo_commit"      { COMMIT; }
+
+session "bar"
+setup                  { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "bar_select"      { SELECT * FROM txn1 WHERE id = 7; }
+step "bar_insert"      { INSERT INTO txn0 SELECT 42, 'bar_insert'; }
+step "bar_commit"      { COMMIT; }
+
+# This session creates the conditions that confused bar's "conflict out"
+# handling in old releases affected by bug:
+session "trouble"
+setup                  { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "trouble_update"  { UPDATE txn1 SET val = 'add physical version for "bar_select"' WHERE id = 7; }
+step "trouble_delete"  { DELETE FROM txn1 WHERE id = 7; }
+step "trouble_abort"   { ABORT; }
+
+permutation "foo_select"
+    "bar_insert"
+    "foo_insert" "foo_commit"
+    "trouble_update"   # Updates tuple...
+    "bar_select"       # Should observe one distinct XID per version
+    "bar_commit"       # "bar" should fail here at the latest
+    "trouble_abort"
+
+# Same as above, but "trouble" session DELETEs this time around
+permutation "foo_select"
+    "bar_insert"
+    "foo_insert" "foo_commit"
+    "trouble_delete"   # Deletes tuple...
+    "bar_select"       # Should observe foo's XID
+    "bar_commit"       # "bar" should fail here at the latest
+    "trouble_abort"