I did a test with the truss command connecting it via the pid but it does not give any message.
As for the version of Postgresql, I would like to adopt what you indicate to me but I do not know a website from which to download the objects. I only know www.perzl.org. www.bullfreeware.com and www.oss4aix.com that for AIX 5.3 only make available the version I have adopted.
Unfortunately, I do not have the environment to compile the sources.