no views about it,

it cannot be done with materialized views.

(synchronous replication would have to be done via triggers - that is a horrifically bad bad bad idea)

If you believe you have a need to have synchronous replication - I would argue with you. I believe what you need is a *single* system - period.

If system A must replicate to system B in real time that means A and B must always be up or neither is up. So available is greatly reduced.

complexity is greatly increased.

maintenance is intensified.

cost is increased.

everything is harder.