From:
Bruno Wolff III <bruno(at)wolff(dot)to>
To:
"Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
Cc:
Andrew Dunstan <andrew(at)dunslane(dot)net>, tgl(at)sss(dot)pgh(dot)pa(dot)us,pgsql-hackers(at)postgresql(dot)org
Subject:
Re: Much Ado About COUNT(*)
Date:
2005-01-12 21:20:43
Message-ID:
20050112212043.GA2137@wolff.to (view raw or flat )
Thread:
2005-01-11 20:15:41 from "Marc G(dot) Fournier" <scrappy(at)postgresql(dot)org>
2005-01-12 08:23:57 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-01-12 08:53:43 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-12 10:38:55 from Reinhard Max <max(at)suse(dot)de>
2005-01-12 10:17:52 from Reinhard Max <max(at)suse(dot)de>
2005-01-12 15:29:23 from Peter Eisentraut <peter_e(at)gmx(dot)net>
2005-01-12 16:29:34 from Reinhard Max <max(at)suse(dot)de>
2005-01-12 17:20:14 from Reinhard Max <max(at)suse(dot)de>
2005-01-12 17:42:56 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-12 18:24:26 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-12 18:55:29 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-12 19:23:44 from Greg Stark <gsstark(at)mit(dot)edu>
2005-01-12 19:36:15 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-12 20:08:37 from Greg Stark <gsstark(at)mit(dot)edu>
2005-01-12 20:41:38 from Jeff Davis <jdavis-pgsql(at)empires(dot)org>
2005-01-12 21:43:46 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2005-01-13 02:45:09 from Jeff Davis <jdavis-pgsql(at)empires(dot)org>
2005-01-13 03:19:18 from Greg Stark <gsstark(at)mit(dot)edu>
2005-01-13 03:50:57 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-12 21:42:06 from "Marek Mosiewicz" <marekmosiewicz(at)poczta(dot)onet(dot)pl>
2005-01-12 19:41:56 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-12 19:52:53 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-12 20:09:04 from Rod Taylor <pg(at)rbt(dot)ca>
2005-01-12 20:59:07 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-12 21:45:51 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-01-12 21:58:14 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-12 22:03:58 from Rod Taylor <pg(at)rbt(dot)ca>
2005-01-12 20:14:51 from "Andrew Dunstan" <andrew(at)dunslane(dot)net>
2005-01-12 20:42:58 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-12 21:02:23 from Jon Jensen <jon(at)endpoint(dot)com>
2005-01-12 21:06:32 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-12 21:17:57 from Jeff Davis <jdavis-pgsql(at)empires(dot)org>
2005-01-12 21:36:55 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-12 21:20:43 from Bruno Wolff III <bruno(at)wolff(dot)to>
2005-01-12 21:56:25 from Bruno Wolff III <bruno(at)wolff(dot)to>
2005-01-12 21:48:33 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-18 20:45:50 from Sailesh Krishnamurthy <sailesh(at)cs(dot)berkeley(dot)edu>
2005-01-18 22:10:48 from Jeff Davis <jdavis-pgsql(at)empires(dot)org>
2005-01-18 22:29:16 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-18 22:42:32 from Sailesh Krishnamurthy <sailesh(at)cs(dot)berkeley(dot)edu>
2005-01-18 23:01:01 from Jeff Davis <jdavis-pgsql(at)empires(dot)org>
2005-01-19 05:09:53 from Christopher Browne <cbbrowne(at)acm(dot)org>
2005-01-12 20:59:51 from Jeff Davis <jdavis-pgsql(at)empires(dot)org>
2005-01-13 10:12:49 from Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>
2005-01-13 04:15:58 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-01-13 04:54:52 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-13 04:57:56 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-01-13 05:06:38 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-13 05:25:09 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-01-13 05:39:56 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-13 14:04:46 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-01-13 15:29:16 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-13 18:22:42 from "D'Arcy J(dot)M(dot) Cain" <darcy(at)druid(dot)net>
2005-01-13 19:20:36 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-16 19:49:45 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2005-01-16 20:11:37 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-16 20:22:11 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-17 00:53:01 from "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>
2005-01-17 01:01:36 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-17 01:24:57 from Jochem van Dieten <jochemd(at)gmail(dot)com>
2005-01-17 01:28:07 from "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>
2005-01-17 01:32:02 from "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>
2005-01-17 01:34:58 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-22 21:19:16 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-01-16 20:38:31 from Jochem van Dieten <jochemd(at)gmail(dot)com>
2005-01-22 20:06:33 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-01-23 08:36:10 from Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com>
2005-01-23 21:36:18 from "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>
2005-01-23 23:41:55 from Mark Kirkwood <markir(at)coretech(dot)co(dot)nz>
2005-01-24 15:28:09 from "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
2005-01-25 07:33:57 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2005-01-25 12:03:28 from Christopher Browne <cbbrowne(at)acm(dot)org>
2005-01-12 18:36:52 from Reinhard Max <max(at)suse(dot)de>
2005-01-12 19:11:32 from Reinhard Max <max(at)suse(dot)de>
2005-01-12 19:59:42 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-12 20:10:16 from Reinhard Max <max(at)suse(dot)de>
2005-01-12 21:38:44 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-01-12 19:28:39 from Kurt Roeckx <Q(at)ping(dot)be>
2005-01-12 19:34:40 from Reinhard Max <max(at)suse(dot)de>
Lists:
pgsql-announce pgsql-hackers pgsql-patches
On Wed, Jan 12, 2005 at 13:42:58 -0700,
"Jonah H. Harris" <jharris(at)tvi(dot)edu> wrote:
> We seem to be in agreement. I'm looking for faster/smarter access to
> data, not the monetary cost of doing so. Isn't it faster/smarter to
> satisfy a query with the index rather than sequentially scanning an
> entire relation if it is possible?
Not necessarily. Also note that Postgres will use an index scan for
count(*) if there is a relatively selective WHERE clause.
> Replying to the list as a whole:
>
> If this is such a bad idea, why do other database systems use it? As a
> businessperson myself, it doesn't seem logical to me that commercial
> database companies would spend money on implementing this feature if it
> wouldn't be used. Remember guys, I'm just trying to help.
Other databases use different ways of handling tuples that are only visible
to some concurrent transactions.
Postgres is also flexible enough that you can make your own materialized
view (using triggers) to handle count(*) if that makes sense for you.
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