| From: | Michail Nikolaev <michail(dot)nikolaev(at)gmail(dot)com> |
|---|---|
| To: | Andrey Borodin <x4mmm(at)yandex-team(dot)ru> |
| Cc: | Simon Riggs <simon(dot)riggs(at)enterprisedb(dot)com>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, Alexander Korotkov <aekorotkov(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, reshkekirill <reshkekirill(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Slow standby snapshot |
| Date: | 2022-08-07 19:28:36 |
| Message-ID: | CANtu0ojtCRHgjaFAUC8DgjrtHEwXNKPqxeoNUd1JFy8Fzmy5AQ@mail.gmail.com |
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| Thread: | |
| Lists: | pgsql-hackers |
Hello, everyone.
> It seems to me storing the index itself is simpler and maybe faster by
> the cycles to perform addition.
Done in v7.
> Since each xid in the tree is always stored to the right, it should be
> possible to make that significantly better by starting each binary
> search from the next element, rather than the start of the array.
Also, looks like it is better to go with `tail = Max(start,
pArray->tailKnownAssignedXids)` (in v1-0001-TODO.patch)
Performance tests show Simon's approach solves the issue without
significant difference in performance comparing to my version.
I need some additional time to provide statistically significant best
coefficients (how often to go compression, minimum number of invalid
xids to start compression).
Thanks,
Michail.
| Attachment | Content-Type | Size |
|---|---|---|
| v7-0001-Currently-KnownAssignedXidsGetAndSetXmin-requires.patch | text/plain | 6.9 KB |
| image.png | image/png | 181.8 KB |
| image.png | image/png | 561.7 KB |
| v1-0001-TODO.patch | text/plain | 6.7 KB |
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