Several people have asked about the terms of the Berkeley DB license,
and the conditions under which users need to pay Sleepycat for
redistribution.
To clarify, you're permitted to redistribute binary copies of your
application, including Berkeley DB, as long as source code is freely
available *somewhere*. Anyone could compile and sell PostgreSQL on
a CD without paying Sleepycat, because the source code remains
available on PostgreSQL.org.
Lots of people ship binary copies of the OpenLDAP directory server,
which uses Berkeley DB. They don't pay us. Only the companies that
ship proprietary directory servers do.
License fees are only required if you make a proprietary version of
the Open Source product. For example, if a vendor took PostgreSQL,
made changes to the backend, and didn't contribute those changes
back to PostgreSQL.org, then the vendor would have to pay Sleepycat
for the right to redistribute our software as a part of the package.
For the purposes of this proposal, we'd consider the PostgreSQL
backend to be the embedding app -- that is, anyone could develop
new proprietary clients, since those don't directly embed our code.
And we stipulate that dynamically-loaded functions that implement
user-defined types and functions don't constitute changes to the
backend.
So the only case in which a license fee would be required would
be if someone forked the backend and kept their changes proprietary.
I'm not aware of anyone distributing a forked version of the
backend now, but I've been outside the community for a while now.
I understand the implications of the BSD and GPL licenses, and why
they're appropriate or inappropriate for particular cases. If the
Berkeley DB license imposes conditions on PostgreSQL that aren't
in keeping with the desires of the developers, then of course the
proposed project won't work.
If you've got additional questions on the license, ask away.
mike