Re: Simplify standby state machine a bit in WaitForWALToBecomeAvailable()

On Wed, Jan 4, 2023 at 12:03 AM Nathan Bossart <nathandbossart(at)gmail(dot)com> wrote:
>
> On Tue, Jan 03, 2023 at 02:53:10PM +0530, Bharath Rupireddy wrote:
> > In summary:
> > the flow when the standby is in crash recovery is pg_wal -> [archive
> > -> pg_wal -> stream] -> [archive -> pg_wal -> stream] -> [] -> [] ...
> > the flow when the standby is in archive recovery is [archive -> pg_wal
> > -> stream] -> [archive -> pg_wal -> stream] -> [] -> [] ...
>
> This is my understanding as well.
>
> > The proposed patch makes the inherent state change to pg_wal after
> > failure to read from archive in XLogFileReadAnyTLI() to explicit by
> > setting currentSource to XLOG_FROM_PG_WAL in the state machine. I
> > think it doesn't alter the existing state machine or add any new extra
> > lookups in pg_wal.
>
> I'm assuming this change would simplify your other patch that modifieѕ
> WaitForWALToBecomeAvailable() [0]. Is that correct?
>
> [0] https://commitfest.postgresql.org/41/3663/

Yes, it does simplify the other feature patch.

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
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