From: | Josh Berkus <josh(at)agliodbs(dot)com> |
---|---|
To: | Greg Stark <stark(at)mit(dot)edu> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Deprecating RULES |
Date: | 2012-10-17 18:13:13 |
Message-ID: | 507EF539.3060202@agliodbs.com |
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Lists: | pgsql-hackers |
Greg,
> 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.
This is excellent. However, if we are actually considerting deprecating
them, we should add the sentence "RULEs may be deprecated in a future
release of PostgreSQL."
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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