Re: Optimizer showing wrong rows in plan - Mailing list pgsql-performance

From Szymon Guz
Subject Re: Optimizer showing wrong rows in plan
Date
Msg-id e4edc9361003280029v7174f84bo72d073aced772206@mail.gmail.com
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In response to Re: Optimizer showing wrong rows in plan  (Tadipathri Raghu <traghu.dba@gmail.com>)
Responses Re: Optimizer showing wrong rows in plan  (Tadipathri Raghu <traghu.dba@gmail.com>)
List pgsql-performance


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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