Re: High QPS, random index writes and vacuum

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От peter plachta
Тема Re: High QPS, random index writes and vacuum
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Msg-id CAGTqnmZZrReJCFtRhGacFzx6UAi388mOEQa1vbCfU1D9MkR8ww@mail.gmail.com
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Ответ на Re: High QPS, random index writes and vacuum  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: High QPS, random index writes and vacuum  (Thomas Munro <thomas.munro@gmail.com>)
Re: High QPS, random index writes and vacuum  (Peter Geoghegan <pg@bowt.ie>)
Список pgsql-performance
Thank you Tom.
Version: I sheepishly admit it's 9.6, 10 and 11 (it's Azure Single Server, that's another story).

I am definitely looking at redoing the way we do UUIDs... but that' s not a trivial change given the volume of data we have + 24/7 workload.

I was trying to understand whether there are any known workarounds for random access + index vacuums. Are my vacuum times 'normal' ?

On Mon, Apr 17, 2023 at 7:01 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
peter plachta <pplachta@gmail.com> writes:
> The company I work for has a large (50+ instances, 2-4 TB each) Postgres
> install. One of the key problems we are facing in vanilla Postgres is
> vacuum behavior on high QPS (20K writes/s), random index access on UUIDs.

Indexing on a UUID column is an antipattern, because you're pretty much
guaranteed the worst-case random access patterns for both lookups and
insert/delete/maintenance cases.  Can you switch to timestamps or
the like?

There are proposals out there for more database-friendly ways of
generating UUIDs than the traditional ones, but nobody's gotten
around to implementing that in Postgres AFAIK.

                        regards, tom lane

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