Skip site navigation (1) Skip section navigation (2)

Re: Querying 19million records very slowly

From: Kjell Tore Fossbakk <kjelltore(at)gmail(dot)com>
To: Michael Glaesemann <grzm(at)myrealbox(dot)com>
Cc: Tobias Brox <tobias(at)nordicbet(dot)com>,pgsql-performance(at)postgresql(dot)org
Subject: Re: Querying 19million records very slowly
Date: 2005-06-22 09:10:42
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
> 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'


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(at)myrealbox(dot)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)---------------------------
> TIP 6: Have you searched our list archives?

In response to


pgsql-performance by date

Next:From: Markus WollnyDate: 2005-06-22 09:14:56
Subject: Forums & tsearch2 - best practices reg. concurrency
Previous:From: Aditya DamleDate: 2005-06-22 09:03:29
Subject: LIKE search with ending % not optimized in v8

Privacy Policy | About PostgreSQL
Copyright © 1996-2017 The PostgreSQL Global Development Group