Re: ANALYZE estimates very wrong reltuples - Mailing list pgsql-admin

From Albe Laurenz
Subject Re: ANALYZE estimates very wrong reltuples
Date
Msg-id A737B7A37273E048B164557ADEF4A58B057B55E1@ntex2010a.host.magwien.gv.at
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In response to ANALYZE estimates very wrong reltuples  (Qingbo Zhou <zhouqb@gmail.com>)
Responses Re: ANALYZE estimates very wrong reltuples  (Qingbo Zhou <zhouqb@gmail.com>)
List pgsql-admin
Qingbo Zhou wrote:
> I have a table which has ~26M records in it. But pg_class shows ~35M in the "reltuples" column.
> last_autovacuum is null, and last_autoanalyze was just on yesterday.
> 
> I tried running vacuum analyze on it, but the analyze result shows:
> 
> INFO:  "[table name]": scanned 30000 of 950145 pages, containing 805842 live rows and 11109 dead rows;
> 30000 rows in sample, 42266462 estimated total rows
> 
> 
> Even worse estimates. I know that it's doing an estimate, but it's too wrong. I have another table for
> which pg_class estimates 3 times the actual number of rows.
> 
> I'm using 9.1.3 [...]

Could you try with different settings for default_statistics_target
(1000, 10000) and see if that changes the result of
ANALYZE VERBOSE?

Yours,
Laurenz Albe

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