Using JCF Commands to Remap Classes and Move Class Instances

Use the class remap and move class instances functionality in the batch JADE Schema Load utility (jadloadb), or the JadeSchemaLoader application in jadclient, jade, or the Application class startApplicationWithParameter method parameter to change class to database file mappings (class maps) and have existing instances moved to match the altered specification in a deployed system.

The operation that moves objects from one database file to another is a special form of database reorganization. Standard operational procedures and precautions recommended when performing a database reorganization therefore apply.

When changing the database file to which a class is mapped, the database file can be defined anywhere within the scope of the current schema or superschema hierarchy; that is, in the schema that defines the class or in any user superschema.

The main characteristics and benefits of this functionality are:

Moving objects from one database file to another is implemented in the database engine as a special type of file reorganization that is similar to a file compaction.
A file split operation in which instances of multiple classes are moved to a single destination file is processed in a single pass of the source file.
Multiple split operations can be executed in parallel, by using a user-specified number of worker threads.
Move object operations are replayable on SDS secondaries and roll-forward recovery, with minimal auditing overhead.
You can specify your own class remap definition and execute the move operation, by using the following JADE command file (JCF) commands in the parameter.

For details about the syntax and command examples, see "Loading Schemas in Batch Mode using jadloadb", in the Jade Schema Load User's Guide.
- Create DbFile
- Delete DbFile
- Remap Class
- MoveInstances
Use these commands in a JADE command file to change the database file mappings for classes with existing instances in a deployed system.

Although you can execute the MoveInstances process online, the files involved are write-locked and not available for updating during the move operation.

The specification of a remap and move instances task entails the creation of a command file comprising specification commands and a final command that triggers the execution of the MoveInstances process.