From 8e154fa5a3a8f56ab21a2bdd1848770569f9aa93 Mon Sep 17 00:00:00 2001 From: Hayato Kuroda Date: Fri, 4 Sep 2026 12:35:21 +0900 Subject: [PATCH v2-PG18 1/2] pg_createsubscriber: ensure output_plugin_libraries include "pgoutput" pg_createsubscriber always uses pgoutput when creating logical replication slots. Check that pgoutput is included in the publisher's output_plugin_libraries setting before proceeding, and provide a useful error and hint when it is not. This also allows --dry-run to detect the invalid configuration before any replication slots are created. --- doc/src/sgml/ref/pg_createsubscriber.sgml | 3 ++ src/bin/pg_basebackup/pg_createsubscriber.c | 44 ++++++++++++++++++- .../t/040_pg_createsubscriber.pl | 24 ++++++++++ 3 files changed, 70 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/ref/pg_createsubscriber.sgml b/doc/src/sgml/ref/pg_createsubscriber.sgml index bb9cc72576c..427df49b692 100644 --- a/doc/src/sgml/ref/pg_createsubscriber.sgml +++ b/doc/src/sgml/ref/pg_createsubscriber.sgml @@ -385,6 +385,9 @@ PostgreSQL documentation replication slots. The source server must have configured to a value greater than or equal to the number of specified databases and existing WAL sender processes. + The source server must also allow the pgoutput output + plugin by setting to include + pgoutput. diff --git a/src/bin/pg_basebackup/pg_createsubscriber.c b/src/bin/pg_basebackup/pg_createsubscriber.c index 42a073e921f..8de72ed4247 100644 --- a/src/bin/pg_basebackup/pg_createsubscriber.c +++ b/src/bin/pg_basebackup/pg_createsubscriber.c @@ -886,6 +886,10 @@ check_publisher(const struct LogicalRepInfo *dbinfo) int cur_walsenders; int max_prepared_transactions; char *max_slot_wal_keep_size; + char *output_plugin_libraries; + char *output_plugin_libraries_copy; + char **allowed_plugins; + bool pgoutput_allowed = false; pg_log_info("checking settings on publisher"); @@ -910,6 +914,7 @@ check_publisher(const struct LogicalRepInfo *dbinfo) * - max_replication_slots >= current + number of dbs to be converted * - max_wal_senders >= current + number of dbs to be converted * - max_slot_wal_keep_size = -1 (to prevent deletion of required WAL files) + * - output_plugin_libraries must include 'pgoutput' * ----------------------------------------------------------------------- */ res = PQexec(conn, @@ -919,7 +924,8 @@ check_publisher(const struct LogicalRepInfo *dbinfo) " pg_catalog.current_setting('max_wal_senders')," " (SELECT count(*) FROM pg_catalog.pg_stat_activity WHERE backend_type = 'walsender')," " pg_catalog.current_setting('max_prepared_transactions')," - " pg_catalog.current_setting('max_slot_wal_keep_size')"); + " pg_catalog.current_setting('max_slot_wal_keep_size')," + " pg_catalog.current_setting('output_plugin_libraries')"); if (PQresultStatus(res) != PGRES_TUPLES_OK) { @@ -935,6 +941,7 @@ check_publisher(const struct LogicalRepInfo *dbinfo) cur_walsenders = atoi(PQgetvalue(res, 0, 4)); max_prepared_transactions = atoi(PQgetvalue(res, 0, 5)); max_slot_wal_keep_size = pg_strdup(PQgetvalue(res, 0, 6)); + output_plugin_libraries = pg_strdup(PQgetvalue(res, 0, 7)); PQclear(res); @@ -947,6 +954,8 @@ check_publisher(const struct LogicalRepInfo *dbinfo) max_prepared_transactions); pg_log_debug("publisher: max_slot_wal_keep_size: %s", max_slot_wal_keep_size); + pg_log_debug("publisher: output_plugin_libraries: %s", + output_plugin_libraries); disconnect_database(conn, false); @@ -994,7 +1003,40 @@ check_publisher(const struct LogicalRepInfo *dbinfo) "max_slot_wal_keep_size"); } + output_plugin_libraries_copy = pg_strdup(output_plugin_libraries); + + if (!SplitGUCList(output_plugin_libraries_copy, ',', &allowed_plugins)) + { + /* + * Should not happen. (Frontend and backend GUC_LIST_QUOTE parsing + * have to remain compatible for pg_dump at minimum.) + */ + pg_fatal("could not parse \"output_plugin_libraries\" setting '%s'", + output_plugin_libraries); + } + + /* Make sure the output_plugin_libraries setting includes "pgoutput" */ + for (char **plugin = allowed_plugins; *plugin; plugin++) + { + if (strcmp(*plugin, "pgoutput") == 0) + { + pgoutput_allowed = true; + break; + } + } + + if (!pgoutput_allowed) + { + pg_log_error("publisher does not allow the \"pgoutput\" output plugin"); + pg_log_error_hint("Add \"pgoutput\" to the configuration parameter \"%s\" and reload the server configuration.", + "output_plugin_libraries"); + failed = true; + } + pg_free(wal_level); + pg_free(output_plugin_libraries); + pg_free(output_plugin_libraries_copy); + pg_free(allowed_plugins); if (failed) exit(1); diff --git a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl index 09014be1361..ab564b93d3b 100644 --- a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl +++ b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl @@ -346,6 +346,30 @@ is($node_s->safe_psql($db1, "SELECT COUNT(*) FROM pg_publication"), $node_s->stop; +# pg_createsubscriber requires that output_plugin_libraries includes 'pgoutput' +# on the publisher. +$node_p->append_conf('postgresql.conf', + "output_plugin_libraries = 'test_decoding'"); +$node_p->reload; + +command_fails_like( + [ + 'pg_createsubscriber', + '--verbose', + '--dry-run', + '--pgdata' => $node_s->data_dir, + '--publisher-server' => $node_p->connstr($db1), + '--socketdir' => $node_s->host, + '--subscriber-port' => $node_s->port, + '--database' => $db1, + ], + qr/publisher does not allow the "pgoutput" output plugin/, + 'primary does not allow to load pgoutput plugin'); + +$node_p->append_conf('postgresql.conf', + "output_plugin_libraries = 'pgoutput, test_decoding'"); +$node_p->reload; + # dry run mode on node S command_ok( [ -- 2.52.0