Re: profiling connection overhead

Robert Haas wrote:
> On Sun, Nov 28, 2010 at 7:15 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Robert Haas <robertmhaas@gmail.com> writes:
> >> One possible way to get a real speedup here would be to look for ways
> >> to trim the number of catcaches.
> >
> > BTW, it's not going to help to remove catcaches that have a small
> > initial size, as the pg_am cache certainly does. ?If the bucket zeroing
> > cost is really something to minimize, it's only the caches with the
> > largest nbuckets counts that are worth considering --- and we certainly
> > can't remove those without penalty.
> 
> Yeah, very true.  What's a bit frustrating about the whole thing is
> that we spend a lot of time pulling data into the caches that's
> basically static and never likely to change anywhere, ever.  I bet the
> number of people for whom <(int4, int4) has any non-standard
> properties is somewhere between slim and none; and it might well be
> the case that formrdesc() is faster than reading the relcache init
> file, if we didn't need to worry about deviation from canonical.  This
> is even more frustrating in the hypothetical situation where a backend
> can switch databases, because we have to blow away all of these cache
> entries that are 99.9% likely to be basically identical in the old and
> new databases.

It is very tempting to look at optimizations here, but I am worried we
might head down the flat-files solution that caused continual problems
in the past.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + It's impossible for everything to be true. +