Transaction overview

A transaction is defined as a group of individual changes to objects on the system that should appear as a single atomic change to the user. A transaction is sometimes called a logical unit of work (LUW). Commitment control is used to ensure that either the entire group of individual changes occur on all systems that participate or that none of the changes occur.

Transactions have the following properties, often referred to as the ACID properties:

The system supports two different types of transactions: Global transactions and Database transactions.

A Global transaction may contain changes both outside and within DB2 for i5/OS. A global transaction is coordinated by an external Transaction Manger using the Open Group XA architecture, or another similar architecture. An application commits or rolls back a global transaction using interfaces provided by the Transaction Manager. The Transaction Manager uses commit protocols defined by the XA architecture, or another architecture, to complete the transaction. DB2 for i5/OS acts as an XA Resource Manager when participating in a global transaction. There are two types of global transactions:

A Database Transaction contains only DB2 for i5/OS changes. The transaction is completed using one of the interfaces provided by the system, such as SQL COMMIT, SQL ROLLBACK, CL COMMIT, CL ROLLBACK, or RPG COMMIT. Locks held on behalf of a database transaction are always scoped to the job performing the transaction. The transactions cannot move from the job that started it.

For more information about Commitment Control and transactions, see Commitment Control in the Information Center Link to Information center.