Rudder

For now, we are only requiring postgresql v8.4.

Version 9.x provide enormous perfomance gain, especially regarding the way we manage agent reports or xml.

Currently, these versions are available by default:

- Debian 7: postgres 9.1
- Debien 7 backports / Debian 8: 9.4

- Ubuntu 14.04: postgres 9.3
- Ubuntu 16.04: postgres 9.5

- Sles 11sp4 / 12 / 12sp1: postgres 9.4

- centos 6: postgres 8.4
- centos 7: postgres 9.2

So we could ask for Postgres 9.2 with migration path from any currently supported server version.

The requirement may be at first only one the documentation, worded in the form "Rudder 4.0 is tested for Postgre 9.2 and higer. It may still works for now with version 8.4 to 9.1, but not garanties are made that this will hold in the future".