Re: Deprecating RULES

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Greg Stark <stark(at)mit(dot)edu>
Cc: Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Deprecating RULES
Date: 2012-10-17 18:41:51
Message-ID: CA+U5nMJ9r7BG63kL02o+YscwMF50ec3t84tgJ6KQDuAz=1LCFA@mail.gmail.com
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On 17 October 2012 18:46, Greg Stark <stark(at)mit(dot)edu> wrote:

> I would suggest something like
>
> Warning: RULES are tricky to use correctly. They rewrite the original
> query into a new query before it is run and it is very hard to
> correctly anticipate and rewrite every possible input query into the
> desired result. There are also unexpected interactions with other
> components when RULES do something unexpected such as rewrite a single
> query to return two result sets.
>
> For most applications it's much simpler and more predictable to use
> TRIGGERs. ROW level triggers are evaluated for each row the original
> query is about to process (or has just finished processing) and this
> makes them much easier to follow. Statement level TRIGGERs can be used
> for audit logs and similar operations which need to run once per
> statement.

I like this very much. Thank you.

--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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