| From: | "Andrey M(dot) Borodin" <x4mmm(at)yandex-team(dot)ru> |
|---|---|
| To: | Ilia Evdokimov <ilya(dot)evdokimov(at)tantorlabs(dot)com> |
| Cc: | Alexander Korotkov <aekorotkov(at)gmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Greg Sabino Mullane <htamfids(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Sample rate added to pg_stat_statements |
| Date: | 2025-01-06 15:57:40 |
| Message-ID: | 6482A576-4465-4E46-A42C-F1767E8DDE30@yandex-team.ru |
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| Lists: | pgsql-hackers |
> On 6 Jan 2025, at 15:50, Ilia Evdokimov <ilya(dot)evdokimov(at)tantorlabs(dot)com> wrote:
>
> Any suggestions for improvements?
The patch looks good to me, just a few nits.
0. Perhaps, we could have a test for edge values of 0 and 1. I do not insist, just an idea to think about.
1. This code seems a little different from your patch. It is trying to avoid engaging PRNG. I'm not sure it's a good idea, but still. Also, it uses "<=", not "<".
xact_is_sampled = log_xact_sample_rate != 0 &&
(log_xact_sample_rate == 1 ||
pg_prng_double(&pg_global_prng_state) <= log_xact_sample_rate);
Thanks!
Best regards, Andrey Borodin.
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