Re: why is there no TRIGGER ON SELECT ?

> -----Original Message-----
> From: Melvin Davidson [mailto:melvin6925(at)yahoo(dot)com]
> Sent: Tuesday, February 22, 2011 9:43 AM
> To: 'Dmitriy Igrishin'; David Johnston
> Cc: pgsql-general(at)postgresql(dot)org
> Subject: Re: why is there no TRIGGER ON SELECT ?
>
> Dave and Dmitriy,
>
> I know a function can be used, but the point is to log a
> table whenever "someone else" does a SELECT on it.
>
> It cannot be depended on that a user will include that (or
> any specific function in a SELECT. iow, when any user does
> "SELECT ... FROM tablex;" then logging should occur.
>
> That cannot happen unless there a trigger of the form:
> CREATE TRIGGER tg_log_table AFTER SELECT ON tablex FOR EACH
> STATEMENT EXECUTE PROCEDURE log_table();
>
> And yes, I know access the to table is restricted, but that
> is also not the point. Suppose an application requires that a
> user/client be charged for each time they access certain data?
>
> The point, and question is, not how to work around the
> problem, but rather, why cannot this functionality be
> implemented in triggerts and rules.
>
> Melvin Davidson
>
>
> Dmitriy
>
> >Why not use function which returns table and wrap the logging
> >(auditing) code in it ?
>
> Because to use a trigger function, you need a trigger, and as
> previously stated, you cannot have a trigger on select. The
> same applies for a rule.
>
> Melvin Davidson
>
>

Somewhat OT (but, m.b. related?):

With every view there is:

RULE "_RETURN" AS ON SELECT TO <view_name>... DO INSTEAD ...

Which PG creates automatically (behind the scene), when view is created.

Is there a way, or did anyone try to modify this Rule?
It is after all "DO INSTEAD" Rule.

Regards,
Igor Neyman