3 files changed, 67 insertions, 0 deletions
diff --git a/src/test/isolation/expected/insert-conflict-toast.out b/src/test/isolation/expected/insert-conflict-toast.out
new file mode 100644
index 00000000000..e86b98020f3
--- /dev/null
+++ b/src/test/isolation/expected/insert-conflict-toast.out
@@ -0,0 +1,15 @@
+Parsed test spec with 3 sessions
+
+starting permutation: s2insert s3insert s1commit
+pg_advisory_xact_lock
+
+               
+step s2insert: 
+  INSERT INTO ctoast (key, val) VALUES (1, ctoast_large_val()) ON CONFLICT DO NOTHING;
+ <waiting ...>
+step s3insert: 
+  INSERT INTO ctoast (key, val) VALUES (1, ctoast_large_val()) ON CONFLICT DO NOTHING;
+ <waiting ...>
+step s1commit: COMMIT;
+step s2insert: <... completed>
+step s3insert: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index 87ab7742fc8..a96a3189871 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -28,6 +28,7 @@ test: insert-conflict-do-nothing
 test: insert-conflict-do-update
 test: insert-conflict-do-update-2
 test: insert-conflict-do-update-3
+test: insert-conflict-toast
 test: delete-abort-savept
 test: delete-abort-savept-2
 test: aborted-keyrevoke
diff --git a/src/test/isolation/specs/insert-conflict-toast.spec b/src/test/isolation/specs/insert-conflict-toast.spec
new file mode 100644
index 00000000000..c5e39ef9e31
--- /dev/null
+++ b/src/test/isolation/specs/insert-conflict-toast.spec
@@ -0,0 +1,51 @@
+# INSERT...ON CONFLICT test on table with TOAST
+#
+# This test verifies that speculatively inserted toast rows do not
+# cause conflicts. It does so by using expression index over a
+# function which acquires an advisory lock, triggering two index
+# insertions to happen almost at the same time. This is not guaranteed
+# to lead to a failed speculative insertion, but makes one quite
+# likely.
+
+setup
+{
+  CREATE TABLE ctoast (key int primary key, val text);
+  CREATE OR REPLACE FUNCTION ctoast_lock_func(int) RETURNS INT IMMUTABLE LANGUAGE SQL AS 'select pg_advisory_xact_lock_shared(1); select $1;';
+  CREATE OR REPLACE FUNCTION ctoast_large_val() RETURNS TEXT LANGUAGE SQL AS 'select array_agg(md5(g::text))::text from generate_series(1, 256) g';
+  CREATE UNIQUE INDEX ctoast_lock_idx ON ctoast (ctoast_lock_func(key));
+}
+
+teardown
+{
+  DROP TABLE ctoast;
+  DROP FUNCTION ctoast_lock_func(int);
+  DROP FUNCTION ctoast_large_val();
+}
+
+session "s1"
+setup
+{
+  BEGIN ISOLATION LEVEL READ COMMITTED;
+  SELECT pg_advisory_xact_lock(1);
+}
+step "s1commit" { COMMIT; }
+
+session "s2"
+setup
+{
+  SET default_transaction_isolation = 'read committed';
+}
+step "s2insert" {
+  INSERT INTO ctoast (key, val) VALUES (1, ctoast_large_val()) ON CONFLICT DO NOTHING;
+}
+
+session "s3"
+setup
+{
+  SET default_transaction_isolation = 'read committed';
+}
+step "s3insert" {
+  INSERT INTO ctoast (key, val) VALUES (1, ctoast_large_val()) ON CONFLICT DO NOTHING;
+}
+
+permutation "s2insert" "s3insert" "s1commit"