Re: trigger/rule question - Mailing list pgsql-sql

From Enrico Weigelt
Subject Re: trigger/rule question
Date
Msg-id 20050502033134.GD24546@nibiru.borg.metux.de
Whole thread Raw
In response to Re: trigger/rule question  ("Ramakrishnan Muralidharan" <ramakrishnanm@pervasive-postgres.com>)
List pgsql-sql
* Ramakrishnan Muralidharan <ramakrishnanm@pervasive-postgres.com> wrote:

Hi,

>     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.


cu
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