| From: | Melanie Plageman <melanieplageman(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | "Drouvot, Bertrand" <bertranddrouvot(dot)pg(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Maciek Sakrejda <m(dot)sakrejda(at)gmail(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, smilingsamay(at)gmail(dot)com, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, Lukas Fittl <lukas(at)fittl(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
| Subject: | Re: Add shared buffer hits to pg_stat_io |
| Date: | 2023-03-09 13:23:46 |
| Message-ID: | CAAKRu_buzeWbu2oL-ntmnKrKd+B=XHYYqMVQc4Ksji7=-+EZRQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Mar 8, 2023 at 2:23 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
>
> On 2023-03-08 13:44:32 -0500, Melanie Plageman wrote:
> > However, I am concerned that, while unlikely, this could be flakey.
> > Something could happen to force all of those blocks out of shared
> > buffers (even though they were just read in) before we hit them.
>
> You could make the test query a simple nested loop self-join, that'll prevent
> the page being evicted, because it'll still be pinned on the outer side, while
> generating hits on the inner side.
Good idea. v3 attached.
| Attachment | Content-Type | Size |
|---|---|---|
| v3-0001-Reorder-pgstatfuncs-local-enum.patch | text/x-patch | 1.0 KB |
| v3-0002-Track-shared-buffer-hits-in-pg_stat_io.patch | text/x-patch | 17.4 KB |
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