Are there any official Postgresql port allocation rules depending on the version?

Question

PostgreSQL

On a spherical machine, you need to have several versions of postgres from 9-11, so what will happen next.
Installation as required in different combinations.
Question: is it possible to be sure that a certain version will always live on a certain port if the installation is default? While he somehow chooses the port himself, and it seems that they are the same on all machines, but I'm not sure, because I didn't find it in the docks.

Answer 1

No, there is no guarantee . There is no reason for the community to change the usual 5432 port. Theoretically, we can change the default port, it is not so difficult technically - but why? We do not guarantee compatibility with future versions and may well decide to break something that needs to be done if the community agrees that it is worth it. We will not give guarantees, but it is quite possible to expect that 5432 will be used by default for a very long time, there is no reason to change it and there are good reasons not to change it.
Well, it’s worth mentioning that the default port can be specified in configs, as a startup parameter, and also at the base compilation stage:
PostgreSQL doesn't do that. It will simply refuse to start if it fails to open the socket. The port number hasn't changed in a very long time, if ever since the very beginning of post-ingres in the 198s.
Here are third-party scripts - those may have some such logic. For example, debian/ubuntu packages, when pg_createcluster is called, will try to set the nearest free port starting from 5432 in the config. There is no dependence on the DBMS version. Need a new cluster? Ok, let's take the nearest free port and configure it to use it.