Remove assertion for replication origins in PREPARE TRANSACTION

When using replication origins, pg_replication_origin_xact_setup() is an
optional choice to be able to set a LSN and a timestamp to mark the
origin, which would be additionally added to WAL for transaction commits
or aborts (including 2PC transactions).  An assertion in the code path
of PREPARE TRANSACTION assumed that this data should always be set, so
it would trigger when using replication origins without setting up an
origin LSN.  Some tests are added to cover more this kind of scenario.

Oversight in commit 1eb6d65.

Per discussion with Amit Kapila and Masahiko Sawada.

Discussion: https://postgr.es/m/YbbBfNSvMm5nIINV@paquier.xyz
Backpatch-through: 11

3 files changed, 108 insertions, 1 deletions

diff --git a/contrib/test_decoding/expected/replorigin.out b/contrib/test_decoding/expected/replorigin.out
index 80773187554..2e9ef7c823b 100644
--- a/contrib/test_decoding/expected/replorigin.out
+++ b/contrib/test_decoding/expected/replorigin.out
@@ -181,3 +181,79 @@ SELECT pg_replication_origin_drop('regress_test_decoding: regression_slot');
  
 (1 row)
 
+-- Set of transactions with no origin LSNs and commit timestamps set for
+-- this session.
+SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_no_lsn', 'test_decoding');
+ ?column? 
+----------
+ init
+(1 row)
+
+SELECT pg_replication_origin_create('regress_test_decoding: regression_slot_no_lsn');
+ pg_replication_origin_create 
+------------------------------
+                            1
+(1 row)
+
+-- mark session as replaying
+SELECT pg_replication_origin_session_setup('regress_test_decoding: regression_slot_no_lsn');
+ pg_replication_origin_session_setup 
+-------------------------------------
+ 
+(1 row)
+
+-- Simple transactions
+BEGIN;
+INSERT INTO origin_tbl(data) VALUES ('no_lsn, commit');
+COMMIT;
+BEGIN;
+INSERT INTO origin_tbl(data) VALUES ('no_lsn, rollback');
+ROLLBACK;
+-- 2PC transactions
+BEGIN;
+INSERT INTO origin_tbl(data) VALUES ('no_lsn, commit prepared');
+PREPARE TRANSACTION 'replorigin_prepared';
+COMMIT PREPARED 'replorigin_prepared';
+BEGIN;
+INSERT INTO origin_tbl(data) VALUES ('no_lsn, rollback prepared');
+PREPARE TRANSACTION 'replorigin_prepared';
+ROLLBACK PREPARED 'replorigin_prepared';
+SELECT local_id, external_id,
+       remote_lsn <> '0/0' AS valid_remote_lsn,
+       local_lsn <> '0/0' AS valid_local_lsn
+       FROM pg_replication_origin_status;
+ local_id |                  external_id                  | valid_remote_lsn | valid_local_lsn 
+----------+-----------------------------------------------+------------------+-----------------
+        1 | regress_test_decoding: regression_slot_no_lsn | f                | t
+(1 row)
+
+SELECT data FROM pg_logical_slot_get_changes('regression_slot_no_lsn', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+                                        data                                         
+-------------------------------------------------------------------------------------
+ BEGIN
+ table public.origin_tbl: INSERT: id[integer]:4 data[text]:'no_lsn, commit'
+ COMMIT
+ BEGIN
+ table public.origin_tbl: INSERT: id[integer]:6 data[text]:'no_lsn, commit prepared'
+ COMMIT
+(6 rows)
+
+-- Clean up
+SELECT pg_replication_origin_session_reset();
+ pg_replication_origin_session_reset 
+-------------------------------------
+ 
+(1 row)
+
+SELECT pg_drop_replication_slot('regression_slot_no_lsn');
+ pg_drop_replication_slot 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_replication_origin_drop('regress_test_decoding: regression_slot_no_lsn');
+ pg_replication_origin_drop 
+----------------------------
+ 
+(1 row)
+
diff --git a/contrib/test_decoding/sql/replorigin.sql b/contrib/test_decoding/sql/replorigin.sql
index b68f819fa1f..2e28a487773 100644
--- a/contrib/test_decoding/sql/replorigin.sql
+++ b/contrib/test_decoding/sql/replorigin.sql
@@ -87,3 +87,35 @@ SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'inc
 
 SELECT pg_drop_replication_slot('regression_slot');
 SELECT pg_replication_origin_drop('regress_test_decoding: regression_slot');
+
+-- Set of transactions with no origin LSNs and commit timestamps set for
+-- this session.
+SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_no_lsn', 'test_decoding');
+SELECT pg_replication_origin_create('regress_test_decoding: regression_slot_no_lsn');
+-- mark session as replaying
+SELECT pg_replication_origin_session_setup('regress_test_decoding: regression_slot_no_lsn');
+-- Simple transactions
+BEGIN;
+INSERT INTO origin_tbl(data) VALUES ('no_lsn, commit');
+COMMIT;
+BEGIN;
+INSERT INTO origin_tbl(data) VALUES ('no_lsn, rollback');
+ROLLBACK;
+-- 2PC transactions
+BEGIN;
+INSERT INTO origin_tbl(data) VALUES ('no_lsn, commit prepared');
+PREPARE TRANSACTION 'replorigin_prepared';
+COMMIT PREPARED 'replorigin_prepared';
+BEGIN;
+INSERT INTO origin_tbl(data) VALUES ('no_lsn, rollback prepared');
+PREPARE TRANSACTION 'replorigin_prepared';
+ROLLBACK PREPARED 'replorigin_prepared';
+SELECT local_id, external_id,
+       remote_lsn <> '0/0' AS valid_remote_lsn,
+       local_lsn <> '0/0' AS valid_local_lsn
+       FROM pg_replication_origin_status;
+SELECT data FROM pg_logical_slot_get_changes('regression_slot_no_lsn', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+-- Clean up
+SELECT pg_replication_origin_session_reset();
+SELECT pg_drop_replication_slot('regression_slot_no_lsn');
+SELECT pg_replication_origin_drop('regress_test_decoding: regression_slot_no_lsn');
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index 28b153abc3c..eb6ecaef474 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -1129,7 +1129,6 @@ EndPrepare(GlobalTransaction gxact)
 
 	if (replorigin)
 	{
-		Assert(replorigin_session_origin_lsn != InvalidXLogRecPtr);
 		hdr->origin_lsn = replorigin_session_origin_lsn;
 		hdr->origin_timestamp = replorigin_session_origin_timestamp;
 	}