Additional settings for DB2 database features
Use these settings for DB2® database.
Feature | Description | Value |
---|---|---|
Currently Committed Semantics |
The DB2 database used the default Cursor Stability (CS) isolation level in all versions until DB2 9.7. If an application changed a row and another application tried to read that row before the first application committed the changes, the second application waited until the commit. You can now set the currently committed semantics of the CS level, which informs DB2 that when the second application tries to read a locked row, it will get an image of what the row looked like before committing the change. In the enhanced currently committed semantics, only committed data is returned, as it was in previous versions. However, now the read operation does not wait for the write operation to release the row locks. Instead, the read operation returns the data before the start of the write operation. The currently committed semantics is turned on by default in the new DB2 9.7 database. The new database configuration parameter, cur_commit is used to override this behavior. For more information, see the Currently committed semantics improve concurrency topic in the DB2 for Linux UNIX and Windows IBM Documentation. Currently committed semantics requires more log space for write operations. In addition, extra space is required for logging the first update of a data row during a transaction, which can have an insignificant or measurable impact on the total log space used. The currently committed semantics feature has
the following limitations:
|
ON |