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From: Josh Berkus <josh@agliodbs.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
To: kenzoid@io.com
Cc: pgsql-sql@postgresql.org
Subject: Re: Timezone issue with date_part
Date: Sat, 2 Nov 2002 13:21:44 -0800
Message-ID: <200211021321.44211.josh@agliodbs.com> (raw)
In-Reply-To: <20169.1036246634@sss.pgh.pa.us>
References: <20021102065654.GA8564@roark.kenzoid.com>
	<20169.1036246634@sss.pgh.pa.us>


Tom,

> (IMHO, the SQL spec is really brain-dead to define timestamp without
> time zone as the default form of timestamp; the variant with time zone
> is much more useful for most applications.  It's far too easy to shoot
> yourself in the foot when working with zoneless timestamps --- usually
> in a way that you won't notice until daylight-savings transition time
> comes around, or you roll out the app to users in other time zones.)

It's pretty easy to shoot yourself in the foot with time zones, as well.   For 
example, most people are thrown off by the daylight-savings-time shift in 
date calculations; for example:

 select '2002-10-20 00:00:00 PDT'::TIMESTAMPTZ + '2 weeks'::INTERVAL
jwnet-> ;
        ?column?
------------------------
 2002-11-02 23:00:00-08

This sort of behavior can really muck with calendar applications.  Of course, 
it could be solved with a DAY/WEEK subtype, but I've already advocated for 
that.

-- 

-Josh Berkus
 Aglio Database Solutions
 San Francisco




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