Re: Rule vs Trigger - Mailing list pgsql-general

From Tom Lane
Subject Re: Rule vs Trigger
Date
Msg-id 18188.1182866666@sss.pgh.pa.us
Whole thread Raw
In response to Re: Rule vs Trigger  ("Albe Laurenz" <all@adv.magwien.gv.at>)
Responses Re: Rule vs Trigger  ("Joshua D. Drake" <jd@commandprompt.com>)
List pgsql-general
"Albe Laurenz" <all@adv.magwien.gv.at> writes:
> Richard Broersma Jr wrote:
>> My understanding is that Triggers offer better performance
>> than rules do.

> A trigger FOR EACH STATEMENT will execute the trigger function
> for each row affacted by the statement.

Huh?  That would be true for a FOR EACH ROW trigger, but a STATEMENT
trigger fires once per statement.

> A rule would only
> execute one additional statement. So if you can do it with a rule
> conveniently, the rule will probably be faster.

I find this unlikely.  The overhead involved in setting up a rule
is probably larger than that involved in calling a trigger.
The real question is whether you need access to the modified data
or not --- a statement-level trigger doesn't currently get that.

            regards, tom lane

pgsql-general by date:

Previous
From: "Gurjeet Singh"
Date:
Subject: Re: a JOIN on same table, but 'slided over'
Next
From: Alvaro Herrera
Date:
Subject: Re: LC_CTYPE and matching accented chars