| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Tomas Vondra <tomas(at)vondra(dot)me>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Melanie Plageman <melanieplageman(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Georgios <gkokolatos(at)protonmail(dot)com>, Konstantin Knizhnik <knizhnik(at)garret(dot)ru>, Dilip Kumar <dilipbalaut(at)gmail(dot)com> |
| Subject: | Re: index prefetching |
| Date: | 2025-08-15 19:45:13 |
| Message-ID: | xw56ywdes77rfiyyy5cpxml5rirj3lthrqx6hezi2rqofz6oj7@lmxwnmcjayjt |
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| Lists: | pgsql-hackers |
Hi,
On 2025-08-15 15:42:10 -0400, Peter Geoghegan wrote:
> On Fri, Aug 15, 2025 at 3:38 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > I see absolutely no effect of the patch with shared_buffers=1GB and a
> > read-only scale 200 pgbench at 40 clients. What data sizes, shared buffers
> > etc. were you testing?
>
> Just to be clear: you are testing with both the index prefetching
> patch and your patch together, right? Not just your own patch?
Correct.
> My shared_buffers is 16GB, with pgbench scale 300.
So there's actually no IO, given that a scale 300 is something like 4.7GB? In
that case my patch could really not make a difference, neither of the changed
branches would ever be reached?
Or were you testing the warmup phase, rather than the steady state?
Greetings,
Andres Freund
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