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Re: Help understanding stat numbers

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Chris Hoover" <revoohc(at)gmail(dot)com>
Cc: "PGSQL Performance" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Help understanding stat numbers
Date: 2007-11-09 07:08:56
Message-ID: 1689.1194592136@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
"Chris Hoover" <revoohc(at)gmail(dot)com> writes:
> If there has been no scans on an index (as according to
> pg_stat_user_indexes), why is pg_statio_user_indexes showing non 0
> values in idx_blks_hit/read?

I grow weary, but I think that "scan" is only incremented by commencing
a SELECT search using the index, whereas the block-level counts are also
incremented when the index is modified by an insert or update.  You may
be looking at indexes that are eating update cycles but not being used
for anything important...

			regards, tom lane

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