Read mostly instances

According to one aspect of the invention, a read-write instance of a multiple-instance database system receives a database statement for execution. The multiple-instance database system comprises a database shared by a plurality read-mostly instances that request only read access to a plurality of user database objects in the database and a plurality of read-write instances that request both read access and write access to the plurality of user database objects. The read-write instance selects one or more read-mostly instances, in the plurality of read-mostly instances, to perform one or more operations that require no write access to the plurality of user data objects.