Re: index file bloating still in 7.4 ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Seum-Lim Gan <slgan(at)lucent(dot)com>
Cc: josh(at)agliodbs(dot)com, pgsql-performance(at)postgresql(dot)org
Subject: Re: index file bloating still in 7.4 ?
Date: 2003-10-19 02:21:00
Message-ID: 16213.1066530060@sss.pgh.pa.us
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Seum-Lim Gan <slgan(at)lucent(dot)com> writes:
> Sample verbose analyze:

> VACUUM VERBOSE ANALYZE hello_rda_or_key;
> INFO: vacuuming "craft.hello_rda_or_key"
> INFO: index "hello242_1105" now contains 740813 row versions in 2477 pages

So what's the problem? That doesn't seem like a particularly bloated
index. You didn't say what datatype the index is on, but making the
most optimistic assumptions, index entries must use at least 16 bytes
each. You're getting about 300 entries per page, compared to the
theoretical limit of 512 ... actually more, since I'm not allowing for
upper btree levels in this calculation ... which says to me that the
page loading is right around the expected btree loading of 2/3.

regards, tom lane

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