Horton

Re: Replication slot is not able to sync up

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Suraj Kharage <suraj.kharage@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-06-03T16:47:45Z
Lists: pgsql-hackers

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  1. Improve log messages and docs for slot synchronization.

On Fri, May 30, 2025 at 6:08 AM Zhijie Hou (Fujitsu)
<houzj.fnst@fujitsu.com> wrote:
> To improve this workload scenario, we can modify pg_sync_replication_slots() to
> wait for the primary slot to advance to a suitable position before completing
> synchronization and removing the temporary slot. This would allow the sync to
> complete as soon as the primary slot advances, whether through
> pg_logical_xx_get_changes() or other ways.

My understanding of this area is limited, but this sounds potentially
promising to me. The current approach seems very timing-dependent.
Depending on the state of the primary vs. the state of the standby, a
call to pg_sync_replication_slots() may either create a slot or fail
to do so. A call at a slightly earlier or later time might have had a
different result. IIUC, this proposal would make different results due
to minor timing variations less probable.

-- 
Robert Haas
EDB: http://www.enterprisedb.com