Re: transforms

Peter, all:

So in addition to the bugs I encountered in getting this patch to work,
we have a design issue to work out: how to load all of the transform
functions. Each transform depends on an optional datatype (like hstore)
and an optional external language (like plperl), which can be loaded
into the database in any order.

Currently Peter is punting (as is proper in a new patch) by having a
separate extension for each combination (hstore/plperl, hstore/plpython,
ltree/plpython, etc.). This is obviously not a maintainable approach in
the long run.

In an ideal world, transformations would load automatically as soon as
all of their prerequisites load. For example, if you load hstore and
plpythonU, then hstore_plpython should automatically load whenever the
second extension is loaded.

However, we currently have no mechanism for this, especially since we
don't know what order the user will load the two extensions in.
Realistically, this would require enhancing the extension mechanism to
track transformations.

Discuss?

--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com