Serialization of an object graph includes class information as well as instance information. If more than one instance of the same class is serialized as separate serialization operations then the class information exists more than once. To eliminate this inefficiency the StoredClassCatalog class will store the class format for all database records stored using a SerialBinding. Remember that if your databases will be running within transactions you must open them within a transaction. Refer to the shipment sample code for examples (the class SampleDatabase in examples_java/src/com/sleepycat/examples/collections/shipment/basic/SampleDatabase.java is a good place to start understanding how to setup this type of environment).