Db2 transaction manager

The Db2 transaction manager (TM) assigns identifiers to transactions, monitors their progress, and takes responsibility for transaction completion and failure. The Db2 TM stores transaction information in the designated TM database.

The database manager provides transaction manager functions that can be used to coordinate the updating of several databases within a single unit of work. The database client automatically coordinates the unit of work, and uses a transaction manager database to register each transaction and track its completion status.

You can use the Db2 transaction manager with Db2 databases. If you have resources other than Db2 databases that you want to participate in a two-phase commit transaction, you can use an XA-compliant transaction manager.

Resync list

In a distributed unit of work (DUOW) environment, transactions which have been prepared but not yet committed are kept in a linked resync list. This list is used to recover from transaction commit or rollback failures due to network, hardware, or software failures.

The resync list is stored in the resync heap, which is in the shared memory of the server.

Each entry in the resync list is called a resync entry. An entry can be a TM (Transaction Manager) entry or an RM (Resource Manager) entry. Each TM entry is uniquely identified by the transaction's XID. Each RM entry is uniquely identified by the transaction's XID and by the RM's alias.