Re: Dept of ugly hacks: eliminating padding space in system indexes

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Mark Mielke <mark(at)mark(dot)mielke(dot)cc>
Cc: Andrew Dunstan <andrew(at)dunslane(dot)net>, pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: Dept of ugly hacks: eliminating padding space in system indexes
Date: 2008-06-23 23:09:11
Message-ID: 4440.1214262551@sss.pgh.pa.us
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Mark Mielke <mark(at)mark(dot)mielke(dot)cc> writes:
>> Tom Lane wrote:
>>> Cutting a third off the size of a system index has got to be worth
>>> something, but is it worth a hack as ugly as this one?

> Were you able to time any speedup?

I didn't try; can you suggest any suitable benchmark?

The performance impact is probably going to be limited by our extensive
use of catalog caches --- once a desired row is in a backend's catcache,
it doesn't take a btree search to fetch it again. Still, the system
indexes are probably "hot" enough to stay in shared buffers most of the
time, and the smaller they are the more space will be left for other
stuff, so I think there should be a distributed benefit.

regards, tom lane

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