Message-ID: <509BCECC.6030108@gmail.com>
Date: Thu, 08 Nov 2012 23:25:00 +0800
From: Rural Hunter <ruralhunter@gmail.com>
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To: Albe Laurenz <laurenz.albe@wien.gv.at>
CC: pgsql-admin@postgresql.org
Subject: Re: analyze log question on parent/children tables
References: <509BBCB0.7050502@gmail.com>
	<D960CB61B694CF459DCFB4B0128514C208AEFFE6@exadv11.host.magwien.gv.at>
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 <D960CB61B694CF459DCFB4B0128514C208AEFFE6@exadv11.host.magwien.gv.at>
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Got it. Thanks.

于2012年11月8日 23:21:33,Albe Laurenz写到:
> Rural Hunter wrote:
>> I'm on 9.1.3. I set auto vacuum off for some tables. I noticed one
>> thing: when I run manual analyze on parent table, It seems the
> children
>> tables are also analyzed. Here is the analyze log:
>>
>> INFO:  analyzing "public.table_parent"
>> INFO:  "table_parent": scanned 0 of 0 pages, containing 0 live rows
> and
>> 0 dead rows; 0 rows in sample, 0 estimated total rows
>> INFO:  analyzing "public.table_parent" inheritance tree
>> INFO:  "table_child1": scanned 11405 of 692945 pages, containing
> 105632
>> live rows and 103 dead rows; 11405 rows in sample, 10739605 estimated
>> total rows
>> INFO:  "table_child2": scanned 1858 of 112866 pages, containing 35818
>> live rows and 0 dead rows; 1858 rows in sample, 2178974 estimated
> total rows
>> ....
>>
>> But when I check the table status in pgAdmin, I noticed the (auto)
>> analyze time of children tables was not logged. So my question here
> is:
>> should I run a separate analyze on children tables?
>
> This ANALYZE will only collect statistics for the parent.
> If you look in pg_stats, you might find two sets of entries
> for the parent table, one with inherited=TRUE and one with
> inherited=FALSE.
> The hierarchy is scanned for the former values.
>
> If you collect statistics manually, you should also run ANALYZE
> on the child tables.
>
> Of course, if you use autovacuum, the right things should happen
> (except that autovacuum doesn't seem to update the inherited
> statistics for the parent table).
>
> Yours,
> Laurenz Albe
>