| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: New WAL record to detect the checkpoint redo location |
| Date: | 2023-10-09 22:31:11 |
| Message-ID: | CA+TgmoZY826g-+KtUxhxOMsGL+3K2MOzPeeZg2hfOb3nuNbfqw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Oct 9, 2023 at 4:47 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> I think we might be able to speed some of this up by pre-compute values so we
> can implement things like bytesleft / UsableBytesInPage with shifts. IIRC we
> already insist on power-of-two segment sizes, so instead of needing to divide
> by a runtime value, we should be able to shift by a runtime value (and the
> modulo should be a mask).
Huh, is there a general technique for this when dividing by a
non-power-of-two? The segment size is a power of two, as is the page
size, but UsableBytesIn{Page,Segment} are some random value slightly
less than a power of two.
--
Robert Haas
EDB: http://www.enterprisedb.com
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