Date: Tue, 09 Nov 2004 10:16:22 +0100
From: Andras Kutrovics <n-drew@freemail.hu>
Subject: Re: Simple SQL Question
In-reply-to: <1099678157.39887.15.camel@taz.oficina>
To: pgsql-sql@postgresql.org
Message-id: <41908AE6.80202@freemail.hu>
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References: <418BB051.6070808@freemail.hu>
	<1099678157.39887.15.camel@taz.oficina>

Franco Bruno Borghesi wrote:


Hi!

Sorry for being late with the answer, I was busy at one of our customer;)

> wouldn't it be easier using offset & limit?: you always select from the 
> table with an itemkey,location order by clause. You save the current 
> offset between requests, and for every request you re-execute the query 
> with a different offset.
   Sure, but sometimes I have to query by name, and dont want to create
   another query component.

> If you still want to go with what you already have, you should keep the 
> lastItemKey and lastLocaltion values between requests, and your where 
> clause should be something like:
> WHERE (itemKey=:lastItemKey AND location>:lastLocation) OR 
> (itemKey>:lastItemKey)

   It works perfectly, but I have to consider the performance issue,
   because if i use 'or' statement, postgres doesn't use index scan,
   and I also have tables with 3 or more keys and 500.000 records , 
where
   the performance of this method is poor.
   Maybe I will end up using limit and offset in case of incremental
   fetching,but if the table is modified between requests, it can behave
   weird.
   Is there a perfect solution to this?

Sorry for the english

Thank you again,

Andras Kutrovics