| From: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com> |
|---|---|
| To: | "Craig A(dot) James" <cjames(at)modgraph-usa(dot)com> |
| Cc: | Christian Paul Cosinas <cpc(at)cybees(dot)com>, 'PFC' <lists(at)peufeu(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Speed Up Offset and Limit Clause |
| Date: | 2006-05-17 19:04:01 |
| Message-ID: | 20060517190400.GV26212@pervasive.com |
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| Lists: | pgsql-performance |
On Tue, May 16, 2006 at 07:20:12PM -0700, Craig A. James wrote:
> >Why I want to use offset and limit is for me to create a threaded
> >application so that they will not get the same results.
>
> In order to return rows 10000 to 15000, it must select all rows from zero
> to 15000 and then discard the first 10000 -- probably not what you were
> hoping for.
>
> You might add a "thread" column. Say you want to run ten threads:
Another possibility is partitioning the table. If you do that using
inheritance-based partitioning, you could just select directly from
different partition tables, which probably be even faster than using a
single table. The downside is it's more work to setup.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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