From: | Andres Freund <andres(at)anarazel(dot)de> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Jeevan Ladhe <jeevan(dot)ladhe(at)enterprisedb(dot)com>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Binary search in fmgr_isbuiltin() is a bottleneck. |
Date: | 2017-10-02 21:44:16 |
Message-ID: | 20171002214416.umejaymxnmfe4mxl@alap3.anarazel.de |
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Lists: | pgsql-hackers |
On 2017-09-28 19:06:27 -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On 2017-09-28 18:52:28 -0400, Tom Lane wrote:
> >> Uh, what? Access to fmgr_nbuiltins shouldn't be part of any critical path
> >> anymore after this change.
>
> > Indeed. But the size of the the oid -> fmgr_builtins index array is
> > relevant now. We could of course just make that dependent on
> > FirstBootstrapObjectId, but that'd waste some memory.
>
> Not enough to notice, considering there are pg_proc OIDs up in the 8K
> range already. We blow 2KB of never-accessed space for far less good
> reason than this.
Done that way. It's a bit annoying, because we've to take care to
initialize the "unused" part of the array with a valid signalling it's
an unused mapping. Can't use 0 for that because fmgr_builtins[0] is a
valid entry. We could introduce a dummy element at that position, but
that doesn't really seem nice either. Therefore the first attached
commit moves find_defined_symbol from genbki to Catalog.pm, so we can
easily extract FirstBootstrapObjectId in Gen_fmgrtab.pl.
Greetings,
Andres Freund
Attachment | Content-Type | Size |
---|---|---|
0001-Move-genbki.pl-s-find_defined_symbol-to-Catalog.pmv2.patch | text/x-diff | 4.3 KB |
0002-Replace-binary-search-in-fmgr_isbuiltin-with-a-loov2.patch | text/x-diff | 6.3 KB |
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