Re: python modul pre-import to avoid importing each time

On Thu, Jun 19, 2014 at 7:50 AM, Rémi Cura <remi.cura@gmail.com> wrote:
> Hey List,
>
> I use plpython with postgis and 2 python modules (numpy and shapely).
> Sadly importing such module in the plpython function is very slow (several
> hundreds of milliseconds).

Is that mostly shapely (which I don't have)?  numpy seems to be pretty
fast, like 16ms.  But that is still slow for what you want, perhaps.

>
> I also don't know if this overhead is applied each time the function is
> called in the same session.

It is not.  The overhead is once per connection, not once per call.
So using a connection pooler could be really be a help here.

> Is there a way to pre-import those modules once and for all,
> such that the python function are accelerated?

I don't think there is.  With plperl you can do this by loading the
module in plperl.on_init and by putting plperl into
shared_preload_libraries so that this happens just at server start up.
But I don't see a way to do something analogous for plpython due to
lack of plpython.on_init.  I think that is because the infrastructure
to do that is part of making a "trusted" version of the language,
which python doesn't have.  (But it could just be that no one has ever
gotten around to adding it.)

Cheers,

Jeff