Re: Can this query be optimized?

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От fstelpstra@yahoo.com
Тема Re: Can this query be optimized?
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Msg-id 9sf7m2$if1$1@news1.xs4all.nl
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Ответ на Re: Can this query be optimized?  (Tom Lane <tgl@sss.pgh.pa.us>)
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Hi,

Isn't it much faster if you extract a substring from the date field?
For example if the date field returns 2001/12/30, you could use the 4th and 
5th position for the month part.

regards,
freek

Tom Lane wrote:

> Claus Heiko Niesen <cniesen@gmx.net> writes:
>> I'm stuck optimizing the following query:
>> select distinct extract(year from date) as year, extract(month from date)
>> as month, date from week_pics order by date desc;
> 
> Perhaps it would work to forget the "distinct" and instead GROUP BY
> date.
> 
> regards, tom lane
> 
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