Re: Binary search in fmgr_isbuiltin() is a bottleneck.

On 2017-09-28 18:52:28 -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > I might be worse than you... But anyway, here's a patch doing
> > so. Looking at profiles, it turned out that having the integer limits as
> > extern variables in a different TU isn't a great idea.
>
> 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.

> > So I moved what
> > used to be fmgrtab.c to fmgrtab.h, and included it directly in fmgr.c.
>
> I'm kind of -0.5 on that. I believe part of the argument for having
> things set up as they were was to allow external code to access the
> fmgr_builtins table (as my speed-test hack earlier today did).

You could still do that, you'd just end up with a second copy. Doesn't
seem bad for such an uncommon case.

Greetings,

Andres Freund