From: Szymon Guz <mabewlun@gmail.com>
To: Tadipathri Raghu <traghu.dba@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Optimizer showing wrong rows in plan
Date: Sun, 28 Mar 2010 09:29:46 +0200
Message-ID: <e4edc9361003280029v7174f84bo72d073aced772206@mail.gmail.com> (raw)
In-Reply-To: <645d9d71003280011q6cf2c6d6p7279605e6e0b4235@mail.gmail.com>
References: <645d9d71003272351x766707c7sadde9aa77bc1c0d3@mail.gmail.com>
<e4edc9361003280002o627b710dhe89c98c18b5d1db3@mail.gmail.com>
<645d9d71003280011q6cf2c6d6p7279605e6e0b4235@mail.gmail.com>
2010/3/28 Tadipathri Raghu <traghu.dba@gmail.com>
> Hi Guz,
>
> Thank you for the prompt reply.
>
>
>> No, the optimizer is not retrieving anything, it just assumes that there
>> are 2400 rows because that is the number of rows that exists in the
>> statictics for this table. The optimizer just tries to find the best plan
>> and to optimize the query plan for execution taking into consideration all
>> information that can be found for this table (it also looks in the
>> statistics information about rows from this table).
>
>
> So, whats it assuming here as rows(2400). Could you explain this.
>
>
>
It is assuming that there are 2400 rows in this table. Probably you've
deleted some rows from the table leaving just one.
regards
Szymon Guz
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Subject: Re: Optimizer showing wrong rows in plan
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