We got some POC at our end and found out Gridgain over REST is much much more faster than Pega Db.
1. Gridgain follows Non relational DB model.
2. Gridgain doesnot maintain Logs
3. Gridgain don't bother about Locks
4. There is no I/O Operation.
5. JVM Heap is any day anytime faster than JDBC.
6. GG is uses Cache data, which may not be real time but extremly fast as they have In-Memory architecture.
Also if the GridGain is configured in the AppServer inside the Organization then only it will act faster. And Our GridGain will be inside the Organization Network where Pega is also Installed. If Not PegaDB wins as there comes the following : As there will be additional layers of Firewall and Routers and other N/W related latency .