Good question. The GPL contains a clause to the effect that "mere aggregation" of a GPL'd piece of code in a
sourcedistribution with unrelated pieces of code is OK, even if those other pieces of code are not GPL'd. But the
contribdirectory is not exactly unrelated to the main Postgres distribution, so I'm not sure that we can point to
thisclause to justify putting a GPL'd program in contrib. It'd be a gray area...
The problem only comes if I, for example, want to distribute all of
postgresql (contrib included) in a non-source (i.e., proprietary) way.
That is fine if contrib includes no GPL code; if it does, I need to
distribute the code for that portion only. Thus, if we want to
maintain as broad a potential as possible (including non-source
distributions) we need to encourage adoption of the BSD license for
all source.
To make it easier for those distributing postgresql to keep track of
this stuff, perhaps we need a gnu (or gpl) directory (like or under
contrib) in which would go GPL code. Then it would be crystal clear
which portion of the code has which restrictions. It would also be
clear that this is an aggregation. This is the mechanism used by
NetBSD for their code tree, which does include some gnu software.
Still, encouraging non-GPL contrib stuff is a good thing in order to
maintain future options, because GPL contrib code _cannot_ be added to
the main tree without affecting the distribution of the entire thing.
Cheers,
Brook