| From: | Craig Ringer <craig(at)postnewspapers(dot)com(dot)au> |
|---|---|
| To: | Vincenzo Romano <vincenzo(dot)romano(at)notorand(dot)it> |
| Cc: | PostgreSQL General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Statement level triggers |
| Date: | 2010-01-20 13:18:49 |
| Message-ID: | 4B5702B9.50706@postnewspapers.com.au |
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| Thread: | |
| Lists: | pgsql-general |
Vincenzo Romano wrote:
> Hi all.
>
> What'd be the behavior of a (plpgsql) trigger function when called as
> a statement level trigger?
> Let's say that a statement will involve more than one row.
> The documentation (v8.4.2, "35.1. Overview of Trigger Behavior") says:
>
> "Statement-level triggers do not currently have any way to examine the
> individual row(s) modified by the statement."
It means you don't have NEW or OLD record-variables. You can still
perform any queries you need to on the table affected and any other
tables of interest.
I find statement-level triggers to be useful mostly for sanity-checking.
I'll have an AFTER statement level trigger verify a certain invariant on
a table - like a table-level CHECK (as opposed to row-level CHECK).
--
Craig Ringer
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