Re: query for a time interval

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От Jim C. Nasby
Тема Re: query for a time interval
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Msg-id 20051222154711.GW72143@pervasive.com
обсуждение исходный текст
Ответ на query for a time interval  (Mark <sendmailtomark@yahoo.com>)
Ответы Re: query for a time interval  (Michael Fuhr <mike@fuhr.org>)
Список pgsql-general
On Wed, Dec 21, 2005 at 11:52:56AM -0800, Mark wrote:
> SELECT id
>   FROM mq
>  WHERE now - start_date > time_to_live;

The problem is you can't use an index on this, because you'd need to
index on (now() - start_date), which obviously wouldn't work. Instead,
re-write the WHERE as:

WHERE start_date < now() - time_to_live
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

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