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Re: Offset

From: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>
To: David Wheeler <david(at)kineticode(dot)com>
Cc: <sfpug(at)postgresql(dot)org>
Subject: Re: Offset
Date: 2003-08-28 18:58:47
Message-ID: 20030828115226.E11166-100000@megazone.bigpanda.com (view raw or flat)
Thread:
Lists: sfpug
On Thu, 28 Aug 2003, David Wheeler wrote:

> On Thursday, August 28, 2003, at 10:36  AM, David Wheeler wrote:
>
> > I wonder if MySQL 4.1 will be able to do this? If not, and I add this
> > to Bricolage, we won't really be able to port it to MySQL. Oh, well!
>
> To answer my own question, it looks like it does:
>
>    http://www.mysql.com/doc/en/Nutshell_4.1_features.html
>
> It calls them "derived tables", which makes sense to me. Couldn't see

One question is whether or not they can have limit clauses applied to
them in the query expression, but they probably can.

> an obvioius place in the PostgreSQL HISTORY file describing when the
> feature was added to PostgreSQL, though. If anyone knows, I'd
> appreciate it.

Looks like 7.2 supports queries of that form from trying against our
unused 7.2 server here.

Performance-wise it should be pretty reasonable since the query plan
for that section basically becomes
 Subquery Scan
  Limit
   <Normal Scan>
where the limit and subquery scan should be nearly free.  And, it save you
from having to join rows that you're not actually using.



In response to

  • Re: Offset at 2003-08-28 17:58:09 from David Wheeler

Responses

  • Re: Offset at 2003-08-28 19:47:49 from David Wheeler

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Next:From: eleinDate: 2003-08-28 19:22:48
Subject: Clarifying File System Syncs
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