Discrete Transaction Management

result of the failure. This option enables the local database administrator to free any locked resources that are held indefinitely as a result of the long-term failure.

If a database must be recovered to a point in the past, Oracle’s recovery facilities enable database administrators at other sites to return their databases to the earlier point in time also. This operation ensures that the global database remains consistent.

See Also: Oracle9i Heterogeneous Connectivity Administrator’s Guide

Discrete Transaction Management

Application developers can improve the performance of short, nondistributed transactions by using the BEGIN_DISCRETE_TRANSACTION procedure. This procedure streamlines transaction processing so that short transactions can run more rapidly.

During a discrete transaction, all changes made to any data are deferred until the transaction commits. Of course, other concurrent transactions are unable to see the uncommitted changes of a transaction whether the transaction is discrete or not.

The following events occur during a discrete transaction:

1.Oracle generates redo information, but stores it in a separate location in memory.

2.When the transaction issues a commit request, Oracle writes the redo information to the redo log file along with other group commits.

3.Oracle applies the changes to the database block directly to the block.

4.Oracle returns control to the application after the commit completes.

This transaction design eliminates the need to generate undo information, because the block is not modified until the transaction is committed, and the redo information is stored in the redo log buffers.

There is no interaction between discrete transactions, which always generate redo, and the NOLOGGING mode, which applies only to direct path operations. Discrete transactions can therefore be issued against tables that have the NOLOGGING attribute set.

See Also: Oracle9i Supplied PL/SQL Packages and Types Reference for more information about the BEGIN_DISCRETE_TRANSACTION procedure

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