Re: [JDBC] old JDBC driver (8.1-JDBC3) can connect to postgresql 9.x ?

​Yes technically, but as John points out ​you could hit a schema catalog change so while it *might* work, there is a chance to hit a problem with pg_catalog updates, the pg_catalog is an internal postgresql table that contains many info consumed by the pgjdbc driver and newer versions of the driver can handle all these variations, so for instance the pgjdbc driver 9.3 Build 1103 can connect without problems to older postgresql versions like the one you are using (8.3) and it can connect to newer postgresql versions like 9.3.

For many years the pgjdbc driver followed the versions of the server to declare some kind of compatibility, basically it means that the version you are using (8.1-404 JDBC3) was essentially for postgresql 8.1 and older, but you are using it for postgresql 8.3 and it works (for you). From the version 9.4.x of the driver that is no longer the case, and the current version 9.4.1212 works on PostgreSQL 9.6 too.

Yes, it should work for postgresql 8.3 and postgresql 9.3 (and everything between) that means that you should be using (based on the Java 5 version) the PgJDBC 9.3 Build 1103 and not the 8.1-404, but as I said before, always test for potential regressions.

​​Let me be cristal clear​, it *might* work ​but again, you might hit a problem with pg_catalog updates and others compatibility issues, so is NOT recomeded to use an older driver version to connect to a newer postgresql version, you should always try to use the latest driver. For example I have a web app that is still on PostgreSQL 9.1 but it's using the latest driver version 9.4.1212. What I mean is that is better to have a new jdbc driver connecting to an older postgresql instance than the opposite.