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From: Bruno Wolff III <bruno@wolff.to>
To: soni de <soni.de@gmail.com>
Cc: Merlin Moncure <mmoncure@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Takes too long to fetch the data from database
Date: Fri, 21 Apr 2006 12:41:49 -0500
Message-ID: <20060421174149.GA13275@wolff.to> (raw)
In-Reply-To: <9f2e40a90604202142x5adbe6f0r7a993f8319619cc7@mail.gmail.com>
References: <9f2e40a90604100021n1cb694d0lb95f318f800f33ee@mail.gmail.com>
	<b42b73150604100845w553dcee6kde20e4b82770aab0@mail.gmail.com>
	<9f2e40a90604110004u787716c2s22bdf53fe349326@mail.gmail.com>
	<b42b73150604110613h2c63ea61oec8035c8e2f4ed98@mail.gmail.com>
	<9f2e40a90604192237i5d3e8f0dl1c8b19887bc34e22@mail.gmail.com>
	<b42b73150604200905h56a0d387xec8c80b4c8d3e901@mail.gmail.com>
	<9f2e40a90604202142x5adbe6f0r7a993f8319619cc7@mail.gmail.com>

On Fri, Apr 21, 2006 at 10:12:24 +0530,
  soni de <soni.de@gmail.com> wrote:
> I don't want to query exactly 81900 rows into set. I just want to fetch 50
> or 100 rows at a time in a decreasing order of stime.(i.e 50 or 100 rows
> starting from last to end).

You can do this efficiently, if stime has an index and you can deal with using
stime from the previous query instead of the record count. The idea is to
select up 50 or 100 records in descending order where the stime is <=
the previous stime. This can give you some overlapping records, so you need
some way to deal with this.

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  Cc: bruno@wolff.to, soni.de@gmail.com, mmoncure@gmail.com
  Subject: Re: Takes too long to fetch the data from database
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