5231ed8262
A cascading WAL sender doing logical decoding (as known as doing its work on a standby) has been using as flush LSN the value returned by GetStandbyFlushRecPtr() (last position safely flushed to disk). This is incorrect as such processes are only able to decode changes up to the LSN that has been replayed by the startup process. This commit changes cascading logical WAL senders to use the replay LSN, as returned by GetXLogReplayRecPtr(). This distinction is important particularly during shutdown, when WAL senders need to send any remaining available data to their clients, switching WAL senders to a caught-up state. Using the latest flush LSN rather than the replay LSN could cause the WAL senders to be stuck in an infinite loop preventing them to shut down, as the startup process does not run when WAL senders attempt to catch up, so they could keep waiting for work that would never happen. Backpatch down to v16, where logical decoding on standbys has been introduced. Author: Alexey Makhmutov <a.makhmutov@postgrespro.ru> Reviewed-by: Ajin Cherian <itsajin@gmail.com> Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Discussion: https://postgr.es/m/52138028-7246-421c-9161-4fa108b88070@postgrespro.ru Backpatch-through: 16
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.