Обсуждение: Create Index on Date portion of timestamp

I am using postgresql 8.1.4.

Is there anyway to create an index equivalent to:
CREATE INDEX i1 ON t1 USING btree  (ts::Date);

So that indexes are used for queries when the field is cast to a date.

On Thu, Oct 12, 2006 at 06:40:22PM -0700, Niederland wrote:
> I am using postgresql 8.1.4.
>
> Is there anyway to create an index equivalent to:
> CREATE INDEX i1 ON t1 USING btree  (ts::Date);
>
> So that indexes are used for queries when the field is cast to a date.

I didn't try it, but you ought to be able to create a functional
index on the to_date() of the column.  I don't know if that will
solve your cast issue, but you could rewrite the CAST into the
to_date form to get around that.

A

--
Andrew Sullivan  | ajs@crankycanuck.ca
"The year's penultimate month" is not in truth a good way of saying
November.
        --H.W. Fowler

"Niederland" <niederland@gmail.com> writes:
> I am using postgresql 8.1.4.
> Is there anyway to create an index equivalent to:
> CREATE INDEX i1 ON t1 USING btree  (ts::Date);

You're short some parentheses:

CREATE INDEX i1 ON t1 USING btree  ((ts::Date));

            regards, tom lane

am  Thu, dem 12.10.2006, um 18:40:22 -0700 mailte Niederland folgendes:
> I am using postgresql 8.1.4.
>
> Is there anyway to create an index equivalent to:
> CREATE INDEX i1 ON t1 USING btree  (ts::Date);

CREATE INDEX i1 ON t1 USING BTREE (to_char(ts, 'dd-mm-yyyy' ));

*untested*


Please, let me know, if this okay.


HTH, Andreas
--
Andreas Kretschmer
Kontakt:  Heynitz: 035242/47215,   D1: 0160/7141639 (mehr: -> Header)
GnuPG-ID:   0x3FFF606C, privat 0x7F4584DA   http://wwwkeys.de.pgp.net