From 29d0a77fa6606f9c01ba17311fc452dabd3f793d Mon Sep 17 00:00:00 2001 From: Amit Kapila Date: Thu, 26 Oct 2023 06:54:16 +0530 Subject: Migrate logical slots to the new node during an upgrade. While reading information from the old cluster, a list of logical slots is fetched. At the later part of upgrading, pg_upgrade revisits the list and restores slots by executing pg_create_logical_replication_slot() on the new cluster. Migration of logical replication slots is only supported when the old cluster is version 17.0 or later. If the old node has invalid slots or slots with unconsumed WAL records, the pg_upgrade fails. These checks are needed to prevent data loss. The significant advantage of this commit is that it makes it easy to continue logical replication even after upgrading the publisher node. Previously, pg_upgrade allowed copying publications to a new node. With this patch, adjusting the connection string to the new publisher will cause the apply worker on the subscriber to connect to the new publisher automatically. This enables seamless continuation of logical replication, even after an upgrade. Author: Hayato Kuroda, Hou Zhijie Reviewed-by: Peter Smith, Bharath Rupireddy, Dilip Kumar, Vignesh C, Shlok Kyal Discussion: http://postgr.es/m/TYAPR01MB58664C81887B3AF2EB6B16E3F5939@TYAPR01MB5866.jpnprd01.prod.outlook.com Discussion: http://postgr.es/m/CAA4eK1+t7xYcfa0rEQw839=b2MzsfvYDPz3xbD+ZqOdP3zpKYg@mail.gmail.com --- doc/src/sgml/ref/pgupgrade.sgml | 78 +++++++++++++++++++++++++++++++++++++++-- 1 file changed, 76 insertions(+), 2 deletions(-) (limited to 'doc/src') diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml index 608193b3070..46e8a0b7467 100644 --- a/doc/src/sgml/ref/pgupgrade.sgml +++ b/doc/src/sgml/ref/pgupgrade.sgml @@ -383,6 +383,79 @@ make prefix=/usr/local/pgsql.new install + + Prepare for publisher upgrades + + + pg_upgrade attempts to migrate logical + slots. This helps avoid the need for manually defining the same + logical slots on the new publisher. Migration of logical slots is + only supported when the old cluster is version 17.0 or later. + Logical slots on clusters before version 17.0 will silently be + ignored. + + + + Before you start upgrading the publisher cluster, ensure that the + subscription is temporarily disabled, by executing + ALTER SUBSCRIPTION ... DISABLE. + Re-enable the subscription after the upgrade. + + + + There are some prerequisites for pg_upgrade to + be able to upgrade the logical slots. If these are not met an error + will be reported. + + + + + + The new cluster must have + wal_level as + logical. + + + + + The new cluster must have + max_replication_slots + configured to a value greater than or equal to the number of slots + present in the old cluster. + + + + + The output plugins referenced by the slots on the old cluster must be + installed in the new PostgreSQL executable directory. + + + + + The old cluster has replicated all the transactions and logical decoding + messages to subscribers. + + + + + All slots on the old cluster must be usable, i.e., there are no slots + whose + pg_replication_slots.conflicting + is true. + + + + + The new cluster must not have permanent logical slots, i.e., + there must be no slots where + pg_replication_slots.temporary + is false. + + + + + + Stop both servers @@ -650,8 +723,9 @@ rsync --archive --delete --hard-links --size-only --no-inc-recursive /vol1/pg_tb Configure the servers for log shipping. (You do not need to run pg_backup_start() and pg_backup_stop() or take a file system backup as the standbys are still synchronized - with the primary.) Replication slots are not copied and must - be recreated. + with the primary.) Only logical slots on the primary are copied to the + new standby, but other slots on the old standby are not copied so must + be recreated manually. -- cgit v1.2.3