agora inbox for postgres@postgres.berkeley.edu  

help / color / mirror / Atom feed

From: Robert.Patrick@cs.cmu.edu
To: postgres@postgres.Berkeley.EDU
Subject: Re: Last 'n' records?
Date: Sun, 18 Sep 1994 00:20:15 -0400 (EDT)
Message-ID: <AiSvzza00hMdQ87lUv@cs.cmu.edu> (raw)
In-Reply-To: <m0qlkES-0009C9C@dl6rai.muc.de>
References: <m0qlkES-0009C9C@dl6rai.muc.de>

Excerpts from internet.postgres: 16-Sep-94 Last 'n' records? Bernhard
Buettner@DL6RAI (1441*)

> A problem arises with the fact that very often a user wants to  retrieve
> "the last 'n'" records of the database. Reading through the manual, I
> could not find an operator to do this. At this time, the query is
> realised as follows:

>      retrieve portal P unique (data.all) sort by date using >
>      fetch 5 in P

> This will take the whole relation, sort it by date and then retrieve the
> last 5 (0.01%). This cannot be the solution, but we can't find any
> better. Any hints, ideas?

The only solution (partial solution, anyway) I can see is to specify a
range on the dates so that only records with recent dates will be
retrieved.  If you really have 10,000 records/month, try limiting your
query to those records which match today's date (or yesterday's and
today's).




==============================================================================
   To add/remove yourself to/from the POSTGRES mailing list: send mail with 
   the subject line ADD or DEL to "postgres-request@postgres.Berkeley.EDU"

   If this fails, send mail to "post_questions@postgres.Berkeley.EDU" and
   a human will deal with it.  DO NOT post to the "postgres" mailing list.
==============================================================================

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: postgres@postgres.berkeley.edu
  Cc: Robert.Patrick@cs.cmu.edu
  Subject: Re: Last 'n' records?
  In-Reply-To: <AiSvzza00hMdQ87lUv@cs.cmu.edu>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox