Re: limit /offset

From: "Pirtea Calin" <pcalin(at)rdsor(dot)ro>
To: "PostgreSQL General" <pgsql-general(at)postgresql(dot)org>
Subject: Re: limit /offset
Date: 2002-03-16 17:09:56
Message-ID: 000e01c1cd0d$757deb60$0100a8c0@dizzy
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> > but when i use offset in the same statement
> > select * from detail2 where id>125000 order by info1 limit 10 offset
> > 10000
> > the plan changes
> > Limit (cost=36.47..36.47 rows=1 width=52)
> > -> Sort (cost=36.47..36.47 rows=333 width=52)
> > -> Seq Scan on detail2 (cost=0.00..22.50 rows=333 width=52)
> > and it takes almost 50 seconds to complete (42.890 sec)
> > Can anyone explain why offset doesn't use the index available?
> >
>
> How many rows does detail2 have? What does explain say for the query and
> how long does it take if you set enable_seqscan=off before it?
>

It doesn't change the explain when i try
set enable_seqscan=off;
select * from detail2 where id>125000 order by info1 limit 10 offset 10000;

And it still takes 42+ seconds

the table has 250000 records.

Thanks in advance.

Best regards,
Aplication Developer
Pirtea Calin Iancu
S.C. SoftScape S.R.L.
pcalin(at)rdsor(dot)ro

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