From: Peter Eisentraut <peter_e@gmx.net>
To: pgsql-sql@postgresql.org
Cc: andrew <andrew.ylzhou@gmail.com>
Subject: Re: filtering after join
Date: Wed, 25 Jan 2006 20:11:13 +0100
Message-ID: <200601252011.13465.peter_e@gmx.net> (raw)
In-Reply-To: <29d3b0b90601250927o2a5ee6e6mc33a7647da4438ce@mail.gmail.com>
References: <29d3b0b90601250927o2a5ee6e6mc33a7647da4438ce@mail.gmail.com>
andrew wrote:
> I want to use a UDF to filter tuples t that are generated after a
> join. More specifially, I have a UDF foo(record), which computes a
> value for a given tuple. I can do the filtering before the join.
> e.g.:
>
> select * from A, B where foo(A)<2 and A.a=B.b;
What makes you think that the filtering happens before the join here?
And why would it matter? The results should be all the same.
--
Peter Eisentraut
http://developer.postgresql.org/~petere/
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: pgsql-sql@postgresql.org
Cc: peter_e@gmx.net, andrew.ylzhou@gmail.com
Subject: Re: filtering after join
In-Reply-To: <200601252011.13465.peter_e@gmx.net>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox