1 files changed, 36 insertions, 0 deletions
diff --git a/src/test/isolation/specs/skip-locked-4.spec b/src/test/isolation/specs/skip-locked-4.spec
new file mode 100644
index 0000000..02994a3
--- /dev/null
+++ b/src/test/isolation/specs/skip-locked-4.spec
@@ -0,0 +1,36 @@
+# Test SKIP LOCKED with an updated tuple chain.
+
+setup
+{
+  CREATE TABLE foo (
+	id int PRIMARY KEY,
+	data text NOT NULL
+  );
+  INSERT INTO foo VALUES (1, 'x'), (2, 'x');
+}
+
+teardown
+{
+  DROP TABLE foo;
+}
+
+session s1
+setup		{ BEGIN; }
+step s1a	{ SELECT * FROM foo WHERE pg_advisory_lock(0) IS NOT NULL ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED; }
+step s1b	{ COMMIT; }
+
+session s2
+step s2a	{ SELECT pg_advisory_lock(0); }
+step s2b	{ UPDATE foo SET data = data WHERE id = 1; }
+step s2c	{ BEGIN; }
+step s2d	{ UPDATE foo SET data = data WHERE id = 1; }
+step s2e	{ SELECT pg_advisory_unlock(0); }
+step s2f	{ COMMIT; }
+
+# s1 takes a snapshot but then waits on an advisory lock, then s2
+# updates the row in one transaction, then again in another without
+# committing, before allowing s1 to proceed to try to lock a row;
+# because it has a snapshot that sees the older version, we reach the
+# waiting code in EvalPlanQualFetch which skips rows when in SKIP
+# LOCKED mode, so s1 sees the second row
+permutation s2a s1a s2b s2c s2d s2e s1b s2f