From 67b15acb4db396a24deab0efefb602227050ed63 Mon Sep 17 00:00:00 2001
From: "Andrei V. Lepikhov" <lepihov@gmail.com>
Date: Wed, 11 Sep 2024 21:16:59 +0200
Subject: [PATCH] Accept invalidation messages before the start of a query in
 transaction

---
 src/backend/tcop/postgres.c                   |  3 +++
 .../isolation/expected/function-replace.out   | 20 ++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../isolation/specs/function-replace.spec     | 26 +++++++++++++++++++
 4 files changed, 50 insertions(+)
 create mode 100644 src/test/isolation/expected/function-replace.out
 create mode 100644 src/test/isolation/specs/function-replace.spec

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 8bc6bea113..4ed8d6f786 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -73,6 +73,7 @@
 #include "tcop/utility.h"
 #include "utils/guc_hooks.h"
 #include "utils/injection_point.h"
+#include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/ps_status.h"
@@ -2774,6 +2775,8 @@ start_xact_command(void)
 		!get_timeout_active(CLIENT_CONNECTION_CHECK_TIMEOUT))
 		enable_timeout_after(CLIENT_CONNECTION_CHECK_TIMEOUT,
 							 client_connection_check_interval);
+
+	AcceptInvalidationMessages();
 }
 
 static void
diff --git a/src/test/isolation/expected/function-replace.out b/src/test/isolation/expected/function-replace.out
new file mode 100644
index 0000000000..b1393be4bf
--- /dev/null
+++ b/src/test/isolation/expected/function-replace.out
@@ -0,0 +1,20 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_exec_fn s2_replace s1_exec_fn s2_drop s1_exec_fn s1_end
+step s1_exec_fn: SELECT test_fn();
+test_fn
+-------
+      1
+(1 row)
+
+step s2_replace: CREATE OR REPLACE FUNCTION test_fn() RETURNS integer LANGUAGE sql AS $$ SELECT 2; $$;
+step s1_exec_fn: SELECT test_fn();
+test_fn
+-------
+      2
+(1 row)
+
+step s2_drop: DROP FUNCTION test_fn;
+step s1_exec_fn: SELECT test_fn();
+ERROR:  function test_fn() does not exist
+step s1_end: END;
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index 143109aa4d..91a8ad67a6 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -115,3 +115,4 @@ test: serializable-parallel-2
 test: serializable-parallel-3
 test: matview-write-skew
 test: lock-nowait
+test: function-replace
diff --git a/src/test/isolation/specs/function-replace.spec b/src/test/isolation/specs/function-replace.spec
new file mode 100644
index 0000000000..54ce156d29
--- /dev/null
+++ b/src/test/isolation/specs/function-replace.spec
@@ -0,0 +1,26 @@
+#
+# Accept invalidation messages before the start of a new query inside the
+# transaction
+#
+
+setup
+{
+  CREATE FUNCTION test_fn() RETURNS integer LANGUAGE sql AS $$ SELECT 1; $$;
+}
+
+session s1
+setup { BEGIN; }
+step s1_exec_fn { SELECT test_fn(); }
+step s1_end { END; }
+
+session s2
+step s2_drop { DROP FUNCTION test_fn; }
+step s2_replace { CREATE OR REPLACE FUNCTION test_fn() RETURNS integer LANGUAGE sql AS $$ SELECT 2; $$; }
+
+permutation
+  s1_exec_fn
+  s2_replace
+  s1_exec_fn
+  s2_drop
+  s1_exec_fn
+  s1_end
\ No newline at end of file
-- 
2.46.0