Noticed that increasing NAMEDATALEN to 128 is still on the TODO.

Given that the addition of namespaces for 7.3 is going to require many
client utilities to be updated anyway, is this a reaonable time to bring
this increase into the standard distribution? It seems like it would be
minor pain whenever we do this, and 7.3 could be as good a time as any.

- J.

Joel BURTON | joel@joelburton.com | joelburton.com | aim: wjoelburton
Knowledge Management & Technology Consultant


Tue, 21 May 2002 11:41:26 -0400
"Joel Burton" <joel@joelburton.com>
Is 7.3 a good time to increase NAMEDATALEN ?
"Joel Burton" <joel@joelburton.com> writes:
> Noticed that increasing NAMEDATALEN to 128 is still on the TODO.
> Given that the addition of namespaces for 7.3 is going to require many
> client utilities to be updated anyway, is this a reaonable time to bring
> this increase into the standard distribution?

Right at the moment we are still trying to understand/eliminate the
performance penalty from increasing NAMEDATALEN.  At last report
someone had measured it as still being annoying large on pgbench.

I have not done any profiling but my best theory at the moment is that
the remaining cost must be in lookup key matching for in-memory hash
tables.  dynahash.c treats keys as fixed-length and always does a
memcmp(), which is going to get slower with bigger NAMEDATALEN, even
if the actually used names aren't getting longer.

The issue might be fixable by teaching this code to use strcmp() for
Name keys, but I haven't tried.

			regards, tom lane

Tue, 21 May 2002 13:53:36 -0400
Tom Lane <tgl@sss.pgh.pa.us>
Re: Is 7.3 a good time to increase NAMEDATALEN ? 
On Tue, 21 May 2002 11:41:26 -0400
"Joel Burton" <joel@joelburton.com> wrote:
> Noticed that increasing NAMEDATALEN to 128 is still on the TODO.

The last benchmarks I saw indicate that there's still a significant
performance hit when increasing NAMEDATALEN, whether to 64 or 128.

Given that only a small percentage of PostgreSQL users need long
identifiers, and *everyone* would suffer the performance hit, I'd
rather that we not touch NAMEDATALEN until more work has been
done on attempting to reduce the performance penalty.

Until then, the people who absolutely, positively must have long
identifiers can just raise NAMEDATALEN themselves.

Cheers,

Neil

-- 
Neil Conway <neilconway@rogers.com>
PGP Key ID: DB3C29FC

Tue, 21 May 2002 15:19:16 -0400
Neil Conway <nconway@klamath.dyndns.org>
Re: Is 7.3 a good time to increase NAMEDATALEN ?