Purpose

Determines the redo log behavior. Typically, redo changes that are generated by update transactions are written to disk immediately when an transaction is committed, and the session waits for the disk write to complete before returning control to the application. For Oracle 10g R2 and higher databases, the log writer can write the redo changes to disk in its own time instead of immediately and return control to the application before the disk write is complete instead of waiting. This property controls this behavior by setting the value of the Oracle COMMIT_WRITE session parameter.

Not waiting for redo log changes to be written to disk improves performance for applications that have both of the following characteristics:

  • Applications that perform update operations.
  • Applications where data integrity is not critical. For example, most banking applications cannot tolerate data loss in the event that the server has a problem writing the redo log changes to disk or fails during the process, but many logging applications for diagnostic purposes can.

Valid Values

serverDefault | waitImmediate | waitBatch | noWaitImmediate | noWaitBatch

Behavior

If set to serverDefault, the driver uses the redo log behavior that is set by the database server.

If set to waitImmediate, the commit operation does not return control to the application until redo changes are written to disk. Redo changes are written to disk immediately. Use this value if your application processes multiple update transactions one at a time.

If set to waitBatch, the commit operation does not return control to the application until redo changes are written to disk. The write task may be deferred by the server until additional transactions are ready to be written to disk. Use this value if your application processes multiple update transactions simultaneously. Using this value when an application performs only a few transactions decreases performance.

If set to noWaitImmediate, redo changes are written to disk immediately, but the commit operation returns control to the application without waiting for this operation to complete. Use this value if your application processes multiple update transactions one at time and data integrity is not critical.

If set to noWaitBatch, the redo write task may be deferred by the server until additional transactions are ready to be written to disk, but the commit operation returns control to the application without waiting for this operation to complete. Use this value if your application processes multiple update transactions simultaneously and data integrity is not critical.

Default

serverDefault

Data Type

String

See also

Performance Considerations