A system and method for a planned migration of service connections from a first database instance to a second database instance in a clustered database. In accordance with an embodiment, a data source and connection pool enable access by a software application to a service on the first database instance. The data source is associated with a parameter specifying a delay-for-planned-draining, and a parameter specifying a planned-draining-period, which are used to rebalance connections when relocating a service. When a service is stopped on the first database instance, the connection pool receives a “service down” event from a notification service, and maintains the connections up to a time corresponding to the delay-for-planned-draining. When a “service up” event is received, the connection pool spreads migration of the connections from the first to second database instance over the planned-draining-period.