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Apache Derby—Off to the Races: Includes Details of IBM® Cloudscape™ by Dan Scott, George Baklarz, Paul C. Zikopoulos

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Locking Considerations

In a multi-user environment, record locking can become an issue that an application needs to handle. When one application is updating a record, that record is “locked” so that no other application can change it. This is critical in maintaining the integrity of the data.

Apache Derby supports four isolation levels: uncommitted read (UR), cursor stability (CS), read stability (RS), and repeatable read (RR). Insert, update, and delete operations always behave the same, no matter what the isolation level is. Only the behavior of SELECT statements varies depending on the isolation level.

Uncommitted Read

The uncommitted read isolation level, also known as dirty read, is the lowest level of isolation supported by Apache Derby. ...

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