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

On Fri, Sep 29, 2023 at 1:00 PM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> On Thu, Sep 28, 2023 at 6:08 PM Zhijie Hou (Fujitsu)
> <houzj.fnst@fujitsu.com> wrote:
>
> IMO, WAL scanning approach looks better. However, if were to optimize
> it by not scanning WAL records for every replication slot
> confirmed_flush_lsn (CFL), start with lowest CFL (min of all slots
> CFL), and scan till the end of WAL.
>

Earlier, I also thought something like that but I guess it won't
matter much as most of the slots will be up-to-date at shutdown time.
That would mean we would read just one or two records. Personally, I
feel it is better to build consensus on the WAL scanning approach,
basically, is it okay to decide as the patch is currently doing or
whether we should expose an API from the decode module as you are
proposing? OTOH, if we want to go with other approach like adding
field in pg_controldata then we don't need to deal with WAL record
types at all.

--
With Regards,
Amit Kapila.