Re: logical: fix recomputation required LSN on restart_lsn-only advancement

On 2026-Apr-21, Chao Li wrote:

> While reading logical replication code, I found an issue in
> LogicalConfirmReceivedLocation().
>
> In LogicalConfirmReceivedLocation(), updated_restart is tracked
> independently from updated_xmin, and the slot is marked dirty and
> saved when either one changed. But after that,
> ReplicationSlotsComputeRequiredLSN() is still only called inside "if
> (updated_xmin)”.

Have you seen this causing issues in any cases beyond REPACK? I'm
wondering about your suggestion to backpatch this change:

> Looks like this issue has been there for a long time, so if this
> analysis is correct, it may also be worth back-patching.

If REPACK is the only affected party, then we don't need to care; as
Antonin said, the xmin advances frequently enough in other cases, so it
shouldn't normally be a problem ...

--
Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/