Re: Trigger to call an external program

On Thu, 4 Dec 2003, Alan Graham wrote:

> I'm doing a low cost, low performance roll your own replication project,
> between various offices around Australia.  The replication is
> asynchronous, and peer to peer.  I've looked at the various replication
> projects, and for one reason or another, they're too hard.

    Agreed.

>
> My design uses jabber as middleware, using python scripts to do the hard
> work.  However, it depends on triggers calling my python scripts to
> work.  I can't find a way to call an external script from a trigger.
> I've searched the archives, and found a few other people asking the same
> question, but no answers (apart from the odd sanctimonious "well you
> shouldn't be doing that..." :-).

    I've just done that. The problem is that the trigger gets fired
even if the query then gets rolled back. So its best to use notify. I
orignally wrote the trigger in python but after finding a bug in the
python scripting for postgres 7.3 I gave up and rewrote in in C its faster
anyway :) My demon script is not bug free however....I want it to inform
users about database changes not for replication however.... so it uses
mu-conference and broardcasts the queries to anyone listening.

>
> I thought I was onto a winner with pgplsh, but I can't get it to compile
> with 7.3.4, although it compiled beautifully with 7.2.1.
>
> Using python as a trigger language also seems to be a non-starter,
> because the restricted python environment isn't yet working.
>
> So...  Is there an easy way to call a script from a trigger?
>
> Thanks
>
> Alan Graham
>
> --
> Alan Graham <alan.graham@infonetsystems.com.au>
>
>
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