Re: compute_query_id and pg_stat_statements
От | Julien Rouhaud |
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Тема | Re: compute_query_id and pg_stat_statements |
Дата | |
Msg-id | 20210514022159.l2v7w2h4al3zjhzn@nol обсуждение исходный текст |
Ответ на | Re: compute_query_id and pg_stat_statements (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
On Thu, May 13, 2021 at 09:47:02PM -0400, Tom Lane wrote: > Julien Rouhaud <rjuju123@gmail.com> writes: > > On Fri, May 14, 2021 at 3:12 AM Bruce Momjian <bruce@momjian.us> wrote: > >> I was surprised it was ~2%. > > > Just to be clear, the 2% was a worst case scenario, ie. a very fast > > read-only query on small data returning a single row. As soon as you > > get something more realistic / expensive the overhead goes away. > > Of course, for plenty of people that IS the realistic scenario that > they care about max performance for. I'm not arguing that the scenario is unrealistic. I'm arguing that retrieving the first row of a join between pg_class and pg_attribute on an otherwise vanilla database may not be the most representative workload, especially when you take into account that it was done on hardware that still took 3 ms to do that. Unfortunately my laptop is pretty old and has already proven multiple time to give unreliable benchmark results, so I'm not confident at all that those 2% are even real outside of my machine.
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