From: Ragnar Hafstað <gnari@simnet.is>
To: Joel Fradkin <jfradkin@wazagua.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: getting count for a specific querry
Date: Fri, 08 Apr 2005 16:25:46 +0000
Message-ID: <1112977546.7447.39.camel@localhost.localdomain> (raw)
In-Reply-To: <000001c53c3e$f4f5b730$797ba8c0@jfradkin>
References: <000001c53c3e$f4f5b730$797ba8c0@jfradkin>
On Fri, 2005-04-08 at 09:29 -0400, Joel Fradkin wrote:
> Our app currently pulls a bunch of data to several query pages.
>
> My idea is to use the limit and offset to return just the first 50
> records, if they hit next I can set the offset.
>
> My understanding was this gets slower as you move further into the
> data, but we have several options to modify the search, and I do not
> believe our clients will page very far intro a dataset.
you might reduce the performance loss if your dataset is ordered by
a UNIQUE index.
select * from mytable where somecondition
ORDER by uniquecol limit 50;
and next:
select * from mytable where somecondition AND uniquecol>?
ORDER by uniquecol limit 50 OFFSET 50;
where the ? is placeholder for last value returned by last query.
if your unique index is a multi-column one, the method is slightly
more complicated, but the same idea.
gnari
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To: pgsql-sql@postgresql.org
Cc: gnari@simnet.is, jfradkin@wazagua.com
Subject: Re: getting count for a specific querry
In-Reply-To: <1112977546.7447.39.camel@localhost.localdomain>
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