Re: [PoC] pg_upgrade: allow to upgrade publisher node - Mailing list pgsql-hackers

On Fri, Sep 22, 2023 at 11:59 AM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> On Thu, Sep 21, 2023 at 6:54 PM Hayato Kuroda (Fujitsu)
> <kuroda.hayato@fujitsu.com> wrote:
> >
>
> 1.
> +    /*
> +     * Use max_slot_wal_keep_size as -1 to prevent the WAL removal by the
> +     * checkpointer process.  If WALs required by logical replication slots
> +     * are removed, the slots are unusable.  This setting prevents the
> +     * invalidation of slots during the upgrade. We set this option when
>
> IIUC, during upgrade we don't want the checkpointer to remove WAL that
> may be needed by logical slots, for that the patch overrides the user
> set value for max_slot_wal_keep_size. What if the WAL is removed
> because of the wal_keep_size setting?
>

We are fine with the WAL removal unless it can invalidate the slots
which is prevented by max_slot_wal_keep_size.

>
> 3. Does this patch support upgrading of logical replication slots on a
> streaming standby?
>

No, and a note has been added by the patch for the same.

--
With Regards,
Amit Kapila.