Re: pgsql: Implement pg_wal_replay_wait() stored procedure

Alvaro Herrera <alvherre@alvh.no-ip.org>

From: Alvaro Herrera <alvherre@alvh.no-ip.org>

To: Alexander Korotkov <aekorotkov@gmail.com>

Cc: Michael Paquier <michael@paquier.xyz>, Heikki Linnakangas <hlinnaka@iki.fi>, Pavel Borisov <pashkin.elfe@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2024-11-04T14:19:26Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Revert pg_wal_replay_wait() stored procedure
- 3a7ae6b3d91e 18.0 landed
Add 'no_error' argument to pg_wal_replay_wait()
- e546989a269d 18.0 landed
Refactor WaitForLSNReplay() to return the result of waiting
- 73da6b8d1b3e 18.0 landed
Make WaitForLSNReplay() issue FATAL on postmaster death
- 6cfebfe88b9a 18.0 landed
Move LSN waiting declarations and definitions to better place
- 5035172e4ab5 18.0 landed
Update oid for pg_wal_replay_wait() procedure
- e658038772f5 18.0 landed
Move pg_wal_replay_wait() to xlogfuncs.c
- 014f9f34d252 18.0 landed
Implement pg_wal_replay_wait() stored procedure
- 3c5db1d6b016 18.0 cited

On 2024-Nov-04, Alexander Korotkov wrote:

> On Mon, Nov 4, 2024 at 8:04 AM Michael Paquier <michael@paquier.xyz> wrote:

> > Using output parameters in a procedure is something I did not recall.
> > Based on your point about not using a function due your argument based
> > on the snapshots, let's just use that and forget about the status
> > function entirely (please?).
> 
> Please, check [1].  Usage of output parameters is a bit awkward too,
> because you need to pass some value in there.  And more importantly,
> usage of output parameters also causes snapshot problem, as it causes
> another snapshot to be held.

I wonder if it would be better to go back to the original idea of using
special DDL syntax rather than a procedure.  It seems we've been piling
up hacks to get around the behavior of procedures, and we seem to have
grown one more to handle repeatable read transactions.

It's looking to me like there's just too much cruft in the quest to
avoid having to reach consensus on new syntax.  This might be a mistake.
Is it possible to backtrack on that decision?

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
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