Search Postgresql Archives

Re: query by partial timestamp

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, Jan 08, 2013 at 04:19:59PM -0600, Kirk Wythers wrote:
> I have a column of type TIMESTAMP, I'd like to query all records from 2011. If it were text I could use a partial such as:
> 
> WHERE
> 	text ~ '2011'
> 
> There must be a simple way to pull the year part out of a timestamp format. Thanks in advance.

using partial checks (like extract, date_part, or even casting field to
date) will have problem with index usage.
the best way to handle it, is to write the parameters using date
arithmetic.
like:
where column >= '2011-01-01' and column < '2012-01-01'

do not be tempted to do:
where column >= '2011-01-01' and column <='2011-12-31'
which is very bad idea, and will cause data loss.

More on index usage:
http://www.depesz.com/2010/09/09/why-is-my-index-not-being-used/

Best regards,

depesz

-- 
The best thing about modern society is how easy it is to avoid contact with it.
                                                             http://depesz.com/


-- 
Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux