"Jonah H. Harris" <jonah.harris@gmail.com> writes:
> In the past, I've just written a C-based function that calls out to system.
Use pltclu, plpythonu, or plperlu, according to taste. They all have
pre-existing solutions for this.
Whether this is a good idea is another question entirely. Lots of
people will tell you it's a horrid idea for PG functions to cause
outside-the-database side effects. The reason is that if the
transaction that called the function aborts later, there is no way
to roll back what was done outside the database, and so the state
outside the database will no longer be in sync with the state inside.
regards, tom lane