Re: trigger/rule question

From: Enrico Weigelt <weigelt(at)metux(dot)de>
To: pgsql-sql <pgsql-sql(at)postgresql(dot)org>
Subject: Re: trigger/rule question
Date: 2005-05-02 03:31:34
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* Ramakrishnan Muralidharan <ramakrishnanm(at)pervasive-postgres(dot)com> wrote:


> Going through you mail, I assume that you are updating the mtime
> only after inserting the record.

An "normal" update (=done by an application or user) should also
update the mtime. But there's an replication subsystem, which writes
should go through untouched.

> It is always possible to check the mtime filed value of the inserted
> record and take action based on it in the trigger.

yeah, but how to detect whether the application has explicitly
written it ?

The only chance I currently have in mind is to use some session
dependent data, i.e. username or some persistant storage (could be
easily done ie. w/ plphp) for this decision. The sync subsystem
has to do some "special" login (ie. separate user or setting the
session wide variable) before doing its work.

I would be happier to let a rule do this, so there's not an extra
function per written row. But all my experiments ran into infinite
recoursion trouble.

> Is it possible to send me detail about the trigger?
The trigger isn't existing yet. I'm currently maintaining the mtime
updates within the application, but I wanna get away from that. It
probably would be interesting, if a normal application couldn't
touch the mtime at all.

Enrico Weigelt == metux IT service
phone: +49 36207 519931 www:
fax: +49 36207 519932 email: contact(at)metux(dot)de
Realtime Forex/Stock Exchange trading powered by postgresSQL :))

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