Because I need to get all rows where datetime is greater than (for example) '2012-10-10 00:00:00' but ignoring timezone, so basically I need to truncate timezone This can be done by converting to timestamp without timezone. -----Mensaje original----- De: Tom Lane [mailto:tgl@xxxxxxxxxxxxx] Enviado el: viernes, 12 de octubre de 2012 05:39 p.m. Para: Anibal David Acosta CC: pgsql-performance@xxxxxxxxxxxxxx Asunto: Re: Do cast affects index usage? "Anibal David Acosta" <aa@xxxxxxxxxxxx> writes: > I have a table with a column of type timestamp with time zone, this > column has an index > If I do a select like this > select * from mytable where cast(my_date as timestamp without time > zone) > > '2012-10-12 20:00:00' > this query will use the index over the my_date column? No. The cast seems rather pointless though ... regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance