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From: Tom Lane <tgl@sss.pgh.pa.us>
To: tim_wilson <tim.wilson@telogis.com>
cc: pgsql-performance@postgresql.org
Subject: Re: Re: autovacuum vacuum creates bad statistics for planner when it
 log index scans: 0
In-reply-to: <1402016119875-5806283.post@n5.nabble.com>
References: <1400459729388-5804416.post@n5.nabble.com>
 <11299.1400559202@sss.pgh.pa.us> <1402016119875-5806283.post@n5.nabble.com>
Comments: In-reply-to tim_wilson <tim.wilson@telogis.com>
 message dated "Thu, 05 Jun 2014 17:55:19 -0700"
Date: Thu, 05 Jun 2014 22:02:01 -0400
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tim_wilson <tim.wilson@telogis.com> writes:
> Thanks for you response Tom:
> but what does index_scans:0 mean? vs index scans: 1?

I believe the former means that VACUUM found no removable tuples, so it
had no need to make any passes over the table's indexes.

(Ordinarily you wouldn't see the number of scans as more than 1, unless
VACUUM removed quite a lot of dead tuples, more than it could remember
within maintenance_work_mem; in which case it would make multiple passes
over the indexes to remove index entries.)

			regards, tom lane


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