From: Cestmir Hybl <cestmirl@freeside.sk>
To: hubert depesz lubaczewski <depesz@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: count(*) using index scan in "query often, update rarely" environment
Date: Fri, 7 Oct 2005 12:14:29 +0200
Message-ID: <9d5b01c5cb27$e7a1c970$131fc39e@stratos> (raw)
References: <935801c5cb20$dcf93a00$131fc39e@stratos>
<9e4684ce0510070254v67e08bcfhb725715803a5de25@mail.gmail.com>
Yes, I can possibly use triggers to maintanin counts of several fixed groups of records or total recordcount (but it's unpractical).
No, I can't speed-up evaluation of generic "count(*) where ()" queries this way.
My question was rather about general performance of count() queries in environment with infrequent updates.
Cestmir
----- Original Message -----
From: hubert depesz lubaczewski
To: Cestmir Hybl
Cc: pgsql-performance@postgresql.org
Sent: Friday, October 07, 2005 11:54 AM
Subject: Re: [PERFORM] count(*) using index scan in "query often, update rarely" environment
On 10/7/05, Cestmir Hybl <cestmirl@freeside.sk> wrote:
Isn't it possible (and reasonable) for these environments to keep track of whether there is a transaction in progress with update to given table and if not, use an index scan (count(*) where) or cached value (count(*)) to perform this kind of query?
if i understand your problem correctly, then simple usage of triggers will do the job just fine.
hubert
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Subject: Re: count(*) using index scan in "query often, update rarely" environment
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