Re: Fsync (flush) all inserted WAL records

Vitaly Davydov <v.davydov@postgrespro.ru>

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From: "Vitaly Davydov" <v.davydov@postgrespro.ru>

To: "Michael Paquier" <michael@paquier.xyz>

Cc: "Aleksander Alekseev" <aleksander@timescale.com>, "PostgreSQL-development" <pgsql-hackers@postgresql.org>

Date: 2024-08-20T15:18:45Z

Lists: pgsql-hackers

Attachments

0001-Add-function-to-return-the-end-LSN-of-the-last-inser.patch (text/x-patch) patch 0001

Dear All,

I would propose a new function like GetXLogInsertRecPtr(), but with some modifications (please, see the attached patch). The result LSN can be passed to XLogFLush() safely. I believe, it will not raise an error in any case. XLogFlush(GetXLogLastInsertEndRecPtr()) will flush (fsync) all already inserted records at the moment. It is what I would like to get.

I'm not sure, we need a SQL function counterpart for this new C function, but it is not a big deal to implement.

With best regards,
Vitaly

On Monday, August 19, 2024 09:35 MSK, Michael Paquier <michael@paquier.xyz> wrote:
 On Wed, Aug 07, 2024 at 06:00:45PM +0300, Aleksander Alekseev wrote:
> Assuming the function has value, as you claim, I see no reason not to
> expose it similarly to pg_current_wal_*(). On top of that you will
> have to test-cover it anyway. The easiest way to do it will be to have
> an SQL-wrapper.

I cannot be absolutely without seeing a patch, but adding SQL
functions in this area is usually very useful for monitoring purposes
of external solutions.
--
Michael