Commitment definition

You create a commitment definition when you use the Start Commitment Control (STRCMTCTL) command to start commitment control on your system. Also, DB2 Universal Database™ (UDB) for iSeries™ automatically creates a commitment definition when the isolation level is other than No Commit.

The commitment definition contains information that pertains to the resources that are being changed under commitment control within that job. The system maintains the commitment control information in the commitment definition as the commitment resources change, until the commitment definition is ended. Each active transaction on the system is represented by a commitment definition. A subsequent transaction can reuse a commitment definition after each commit or rollback of an active transaction.

A commitment definition generally includes:

• The parameters on the STRCMTCTL command.
• The current status of the commitment definition.
• Information about database files and other committable resources that contain changes that are made during the current transaction.

For commitment definitions with job-scoped locks, only the job that starts commitment control knows that commitment definition. No other job knows that commitment definition.

Programs can start and use multiple commitment definitions. Each commitment definition for a job identifies a separate transaction that has committable resources associated with it. These transactions can be committed or rolled back independently from transactions that are associated with other commitment definitions that are started for the job.

• Scope for a commitment definition
  The scope of a commitment definition determines which programs will use that commitment definition, and how locks acquired during transactions are scoped.
• Commitment definition names
  The system gives names to all commitment definitions that are started for a job.
• Example: Jobs and commitment definitions
  This figure shows an example of a job that uses multiple commitment definitions.