From: | Jorge Godoy <jgodoy(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: ON UPDATE trigger question |
Date: | 2007-09-12 22:52:51 |
Message-ID: | 200709121952.51624.jgodoy@gmail.com |
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Lists: | pgsql-general |
On Wednesday 12 September 2007 15:56:13 Josh Trutwin wrote:
> If I create an ON UPDATE trigger run on each row after update, does
> the trigger fire only on rows affected by the update or for all rows?
>
> For example:
>
> CREATE TRIGGER my_update_trigger
> AFTER UPDATE ON my_table
> FOR EACH ROW
> EXECUTE PROCEDURE my_update_proc;
>
> UPDATE my_table SET my_val = my_val * 2;
>
> Will the trigger fire on rows that have NULL for my_val?
I haven't tested what you asked (you can do that easily), but if this is your
concern and if you have a huge table you might want to add a WHERE
clause: "WHERE my_val IS NOT NULL".
--
Jorge Godoy <jgodoy(at)gmail(dot)com>
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