If you don't have secondary indexes, views and immutable table then upgrade from 4.5 to 4.9 will just add some new columns in SYSTEM.CATALOG and re-creates STATS table. 
but still we have not tested an upgrade from 4.5 to 4.9, it is always advisable to do stop after every two versions (especially in production).

On Tue, Jun 27, 2017 at 3:58 AM, Pedro Boado <pedro.boado@gmail.com> wrote:
Hi guys

we are planning a migration from our current version of Apache Phoenix ( 4.5 ) to 4.9. We checked the upgrade guide and we are aware that Phoenix maintains two versions-back compatibility but...  is it really needed to do a stop in 4.7 to have a safe migration? 

We don't have any secondary indexes or views but just regular phoenix tables.