Re: [SQL] OFFSET impact on Performance???

From: Oleg Bartunov <oleg(at)sai(dot)msu(dot)su>
To: PFC <lists(at)boutiquenumerique(dot)com>
Cc: alex(at)neteconomist(dot)com, Greg Stark <gsstark(at)mit(dot)edu>, Merlin Moncure <merlin(dot)moncure(at)rcsonline(dot)com>, Andrei Bintintan <klodoma(at)ar-sd(dot)net>, pgsql-performance(at)postgresql(dot)org
Subject: Re: [SQL] OFFSET impact on Performance???
Date: 2005-01-27 10:33:00
Message-ID: Pine.GSO.4.62.0501271332200.6701@ra.sai.msu.su
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On Thu, 27 Jan 2005, PFC wrote:

>
>> Thats a really good idea, just store a list of the sorted ids in the
>> temp table - small amount of data for insert... I like it!
>>
>> Alex Turner
>> NetEconomist
>
> The best part is that you can skip the LIMIT/OFFSET entirely if you
> put page numbers in your cache table while inserting into it, via a temporary
> sequence or something. Retrieving the results will then be very fast, but
> beware that SELECT * FROM table WHERE id =ANY( array ) won't use an index, so

contrib/intarray provides index access to such queries.

> you'll have to trick the thing by generating a query with IN, or joining
> against a SRF returning the elements of the array one by one, which might be
> better.
>
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>

Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83

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