Re: libpq API incompatibility between 7.4 and 8.0

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:

> In fact by upping the major every time will 7.2 clients automatically use
> the 7.3 libpq or will they have to be relinked?

If you do not bump the soname then 7.2 clients will automatically immediately
start using the new library when it's installed. (actually when ldconfig is
run, which distributions will normally do automatically).

If you do bump the versions then 7.2 clients will continue to use 7.2
libraries. If you have 7.2 clients, or even clients like DBD::Pg or other
third-party libpq apps then you would have to relink them to use the new
libraries. But you would probably just keep around both sets of libraries.

I could see valid arguments for either when it comes to whether to bump it
when it's not strictly necessary.

If libpq were used by lots of external applications using the public interface
then bumping it more than necessary means people have to keep around extra
versions for no reason.

On the other hand if libpq is seen as an integral part of the postgres package
and its specific behaviour is important then not bumping the version forces
admins to pick one version for everything when they might prefer that 7.2
clients stick with the 7.2 library.

In a way the fact that you release new libpq versions when you release
security releases for old releases like 7.3 or 7.4 sort of already implies an
answer. If you thought the new library was plug-in compatible and should
completely replace the old library automatically you wouldn't continue to
release modified versions of the old library, you would just release HEAD for
libpq all the time.

--
greg