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Re: Created Index is not used

From: Kjeld Peters <kjeld(dot)peters(at)profiling-company(dot)de>
To: Markus Schaber <schabi(at)logix-tt(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Created Index is not used
Date: 2006-02-23 14:09:10
Message-ID: 43FDC206.2090102@profiling-company.de (view raw or flat)
Thread:
Lists: pgsql-performance
Hi Markus,

first of all thanks for your quick reply!

Markus Schaber wrote:
> Kjeld Peters wrote:
>>Select and update statements are quite slow on a large table with more
>>than 600,000 rows. The table consists of 11 columns (nothing special).
>>The column "id" (int8) is primary key and has a btree index on it.
>>
>>The following select statement takes nearly 500ms:
>>
>>SELECT * FROM table WHERE id = 600000;
> 
> 
> Known issue which is fixed in 8.X servers, postgreSQL sees your 600000
> as int4 literal and does not grasp that the int8 index works for it.
> 
> SELECT * FROM table WHERE id = 600000::int8;
> 
> should do it.

After I appended "::int8" to the query, selecting the table takes only 
40-50ms. That's a great performance boost!

> Btw, you should update to 7.4.12, there are importand bug fixes and it
> is upgradable "in place", without dumping and reloading the database.

I guess I'll test an upgrade to version 8.1.

Thanks again for your and Ragnar's help!

Kjeld

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