Re: Something is wrong with wal_compression - Mailing list pgsql-hackers

From Maciek Sakrejda
Subject Re: Something is wrong with wal_compression
Date
Msg-id CAOtHd0Bde_VaL_n9M-u25L41FqpBLWGZt+BzRQ2gFO4E4unpXw@mail.gmail.com
Whole thread Raw
In response to Re: Something is wrong with wal_compression  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
On Fri, Jan 27, 2023, 18:58 Andres Freund <andres@anarazel.de> wrote:
Hi,

On 2023-01-27 16:15:08 +1300, Thomas Munro wrote:
> It would be pg_current_xact_id() that would have to pay the cost of
> the WAL flush, not pg_xact_status() itself, but yeah that's what the
> patch does (with some optimisations).  I guess one question is whether
> there are any other reasonable real world uses of
> pg_current_xact_id(), other than the original goal[1].

txid_current() is a lot older than pg_current_xact_id(), and they're backed by
the same code afaict. 8.4 I think.

Unfortunately txid_current() is used in plenty montiring setups IME.

I don't think it's a good idea to make a function that was quite cheap for 15
years, suddenly be several orders of magnitude more expensive...

As someone working on a monitoring tool that uses it (well, both), +1. We'd have to rethink a few things if this becomes a performance concern.

Thanks,
Maciek

pgsql-hackers by date:

Previous
From: Andres Freund
Date:
Subject: Re: Something is wrong with wal_compression
Next
From: Andres Freund
Date:
Subject: Re: Something is wrong with wal_compression