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

On 2017-09-28 19:06:27 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.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