Re: query by partial timestamp

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

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