On Mon, Apr 27, 2009 at 11:10 AM, Martijn van Oosterhout <klep...@svana.org>wrote:
> On Mon, Apr 27, 2009 at 10:51:45AM -0400, Kynn Jones wrote: > > I need to compile some code that uses libpq. For this I need to > determine > > the directories to use for the header and library files. > > > > The machine I'm using has multiple copies of the files libpq-fe.h and > > libpq.a. How can I determine which one of all these copies are the ones > > that correspond to the Pg server that is currently running on this > system? > > (FWIW, the OS here is Ubuntu Linux.) > > In general you don't need to match the server version, the protocol hasn't changed much in a while so as long as it's less than a few years > old it'll work. This statement contradicts the experience I described in my original post: the choice of header and/or library files is absolutely critical. The wrong choice lead to very bizarre connection failures. > > I tried the naive approach of using the "newest" versions of these files, > as > > measured by their modification times. This produced disastrous results. > > The code compiled, but resulted in a program that failed in bizarre and > > unpredictable ways, which strongly hinted at one or more silent > segmentation > > violations in the C code. I conjectured that this was the result of a > > mismatched header or library file. Sure enough, the bizarre failures > > disappeared when I used a different set of header and library files. > > Given you're using Ubuntu, why not just install postgresql-dev and use > /usr/include/postgresql. > I don't have root privileges on this machine, so I could not install postgresql-dev, but, as it happens, /usr/include/postgresql already exists in this machine, in it is, in fact, the version that worked. But this is not the problem that my question was about. The problem is: *how to ensure* that the versions of libpq header and library files used for compiling programs will work properly with a specific Postgres server. kynn
