Horton

Disallow changing slot's failover option in transaction block

Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>

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From: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2024-04-16T06:32:11Z
Lists: pgsql-hackers

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Hi,

Kuroda-San reported an issue off-list that:

If user execute ALTER SUBSCRIPTION SET (failover) command inside a txn block
and rollback, only the subscription option change can be rolled back, while the
replication slot's failover change is preserved.

This is because ALTER SUBSCRIPTION SET (failover) command internally executes
the replication command ALTER_REPLICATION_SLOT to change the replication slot's
failover property, but this replication command execution cannot be
rollback.

To fix it, I think we can prevent user from executing ALTER SUBSCRIPTION set
(failover) inside a txn block, which is also consistent to the ALTER
SUBSCRIPTION REFRESH/DROP SUBSCRIPTION command. Attach a small
patch to address this.

Best Regards,
Hou Zhijie

Commits

  1. Fix the handling of the failover option in subscription commands.