> 8.2, 8.3, and 8.4 are all Major releases of the PostgreSQL product. For > most other products it would as if the numbering went from "15, to 16, to > 17". The last 8.x release was 8.4 (so, there were 5 major releases that all > shared the same prefix value of 8) and the 9.x series goes from 9.0 to 9.6 > (presently in beta). Instead of 9.7 we will be going to 10.0 AND at the > same time modernizing our numbering scheme to lose the prefix-suffix > components. IOW, after 10.0 the next major release will be 11.0. The .0 > will increment for minor releases in which we only apply bug-fixes. There > will no longer be a third number.
Currently are minor upgrades reversible, that is, can we rollback from 9.4.3 to 9.4.2.
I suspect there may be obscure corner-cases that could trip one up because this is not done often and not presently tested, at all. But in theory and as intended, yes.
Minor versions only differ in their binaries. The stored data is unaffected. Any 9.4.x release should be able to point as a data directory initialized by any 9.4 binary and operate "correctly".
