From: Kjell Tore Fossbakk <kjelltore@gmail.com>
To: Michael Glaesemann <grzm@myrealbox.com>
Cc: Tobias Brox <tobias@nordicbet.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Querying 19million records very slowly
Date: Wed, 22 Jun 2005 11:10:42 +0200
Message-ID: <e79986c50506220210578776e@mail.gmail.com> (raw)
In-Reply-To: <8B2836FF-F335-49A4-8131-8EF2D02100F9@myrealbox.com>
References: <e79986c505062112094f579a9b@mail.gmail.com>
<42B8719A.6040809@refractions.net>
<op.ssqot4d4th1vuj@localhost>
<e79986c505062200457fe97695@mail.gmail.com>
<20050622080357.GW7839@tobias>
<e79986c5050622011828dd4b41@mail.gmail.com>
<20050622083921.GZ7839@tobias>
<8B2836FF-F335-49A4-8131-8EF2D02100F9@myrealbox.com>
> Try to type in '2005-06-21 16:36:22+08' directly in the query, and see if it
> makes changes. Or probably '2005-06-21 10:36:22+02' in your case ;-)
Which one does Pg read fastes? Does he convert datetime in the table,
then my where clause and check, for each row? How does he compare a
datetime with a datetime? Timestamp are easy, large number bigger than
another large number..
time (datetime) > '2005-06-21 10:36:22+02'
or
time (timestamp) > 'some timestamp pointing to yesterday'
Hmm.. I cant find any doc that describes this very good.
On 6/22/05, Michael Glaesemann <grzm@myrealbox.com> wrote:
>
> On Jun 22, 2005, at 5:39 PM, Tobias Brox wrote:
>
> > (btw, does postgresql really handles timezones? '+02' is quite
> > different
> > from 'CET', which will be obvious sometime in the late autoumn...)
>
> Yes, it does. It doesn't (currently) record the time zone name, but
> rather only the offset from UTC. If a time zone name (rather than UTC
> offset) is given, it is converted to the UTC offset *at that
> timestamptz* when it is stored. For time zones that take into account
> DST, their UTC offset changes during the year, and PostgreSQL records
> the equivalent UTC offset for the appropriate timestamptz values.
>
> There has been discussion in the past on storing the time zone name
> with the timestamptz as well, though no one has implemented this yet.
>
> Michael Glaesemann
> grzm myrealbox com
>
>
> ---------------------------(end of broadcast)---------------------------
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>
> http://archives.postgresql.org
>
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To: pgsql-performance@postgresql.org
Cc: kjelltore@gmail.com, grzm@myrealbox.com, tobias@nordicbet.com
Subject: Re: Querying 19million records very slowly
In-Reply-To: <e79986c50506220210578776e@mail.gmail.com>
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