Don't advance origin during apply failure.

The logical replication parallel apply worker could incorrectly advance
the origin progress during an error or failed apply. This behavior risks
transaction loss because such transactions will not be resent by the
server.

Commit 3f28b2fcac addressed a similar issue for both the apply worker and
the table sync worker by registering a before_shmem_exit callback to reset
origin information. This prevents the worker from advancing the origin
during transaction abortion on shutdown. This patch applies the same fix
to the parallel apply worker, ensuring consistent behavior across all
worker types.

As with 3f28b2fcac, we are backpatching through version 16, since parallel
apply mode was introduced there and the issue only occurs when changes are
applied before the transaction end record (COMMIT or ABORT) is received.

Author: Hou Zhijie <houzj.fnst@fujitsu.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Backpatch-through: 16
Discussion: https://postgr.es/m/TY4PR01MB169078771FB31B395AB496A6B94B4A@TY4PR01MB16907.jpnprd01.prod.outlook.com
Discussion: https://postgr.es/m/TYAPR01MB5692FAC23BE40C69DA8ED4AFF5B92@TYAPR01MB5692.jpnprd01.prod.outlook.com

diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index 9b5c641941fad28f724c92f3d622c1795d9096cb..d6bbffd7c8da3b6a15e214edd6b2201ecc56873f 100644 (file)
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -4544,6 +4544,23 @@ InitializeApplyWorker(void)
                                                MySubscription->name)));
 
        CommitTransactionCommand();
+
+       /*
+        * Register a callback to reset the origin state before aborting any
+        * pending transaction during shutdown (see ShutdownPostgres()). This will
+        * avoid origin advancement for an incomplete transaction which could
+        * otherwise lead to its loss as such a transaction won't be sent by the
+        * server again.
+        *
+        * Note that even a LOG or DEBUG statement placed after setting the origin
+        * state may process a shutdown signal before committing the current apply
+        * operation. So, it is important to register such a callback here.
+        *
+        * Register this callback here to ensure that all types of logical
+        * replication workers that set up origins and apply remote transactions
+        * are protected.
+        */
+       before_shmem_exit(replorigin_reset, (Datum) 0);
 }
 
 /* Logical Replication Apply worker entry point */
@@ -4581,19 +4598,6 @@ ApplyWorkerMain(Datum main_arg)
 
        InitializeApplyWorker();
 
-       /*
-        * Register a callback to reset the origin state before aborting any
-        * pending transaction during shutdown (see ShutdownPostgres()). This will
-        * avoid origin advancement for an in-complete transaction which could
-        * otherwise lead to its loss as such a transaction won't be sent by the
-        * server again.
-        *
-        * Note that even a LOG or DEBUG statement placed after setting the origin
-        * state may process a shutdown signal before committing the current apply
-        * operation. So, it is important to register such a callback here.
-        */
-       before_shmem_exit(replorigin_reset, (Datum) 0);
-
        InitializingApplyWorker = false;
 
        /* Connect to the origin and start the replication. */

diff --git a/src/test/subscription/t/023_twophase_stream.pl b/src/test/subscription/t/023_twophase_stream.pl
index 0303807846e48b7a69fca9da37f47d8a1be992da..39ad688a7bd9514147ed7f11f71134d3cfbd912a 100644 (file)
--- a/src/test/subscription/t/023_twophase_stream.pl
+++ b/src/test/subscription/t/023_twophase_stream.pl
@@ -429,6 +429,51 @@ $result =
   $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM test_tab_2");
 is($result, qq(1), 'transaction is committed on subscriber');
 
+# Test the ability to re-apply a transaction when a parallel apply worker fails
+# to prepare the transaction due to insufficient max_prepared_transactions
+# setting.
+$node_subscriber->append_conf(
+       'postgresql.conf', qq(
+max_prepared_transactions = 0
+debug_logical_replication_streaming = buffered
+));
+$node_subscriber->restart;
+
+$node_publisher->safe_psql(
+       'postgres', q{
+       BEGIN;
+       INSERT INTO test_tab_2 values(2);
+       PREPARE TRANSACTION 'xact';
+       COMMIT PREPARED 'xact';
+       });
+
+$offset = -s $node_subscriber->logfile;
+
+# Confirm the ERROR is reported because max_prepared_transactions is zero
+$node_subscriber->wait_for_log(
+       qr/ERROR: ( [A-Z0-9]+:)? prepared transactions are disabled/,
+       $offset);
+
+# Confirm that the parallel apply worker has encountered an error. The check
+# focuses on the worker type as a keyword, since the error message content may
+# differ based on whether the leader initially detected the parallel apply
+# worker's failure or received a signal from it.
+$node_subscriber->wait_for_log(
+       qr/ERROR: .*logical replication parallel apply worker.*/,
+       $offset);
+
+# Set max_prepared_transactions to correct value to resume the replication
+$node_subscriber->append_conf('postgresql.conf',
+       qq(max_prepared_transactions = 10));
+$node_subscriber->restart;
+
+$node_publisher->wait_for_catchup($appname);
+
+# Check that transaction is committed on subscriber
+$result =
+  $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM test_tab_2");
+is($result, qq(2), 'transaction is committed on subscriber after retrying');
+
 ###############################
 # check all the cleanup
 ###############################