Re: Something is wrong with wal_compression
От | Maciek Sakrejda |
---|---|
Тема | Re: Something is wrong with wal_compression |
Дата | |
Msg-id | CAOtHd0Bde_VaL_n9M-u25L41FqpBLWGZt+BzRQ2gFO4E4unpXw@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: Something is wrong with wal_compression (Andres Freund <andres@anarazel.de>) |
Список | 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
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