Chapter 16. Locking and Concurrency

• Locking data

• Avoiding locks

• Claims and drains

• Locking issues and problems

• Designing for concurrency

It would be easy to have one process simply lock all the data while using it, but that, of course, would lead to other applications' being unable to access the data during this time. Concurrency, the ability for multiple applications to access the same data at the same time, needs to be allowed but also controlled in order to prevent lost updates, access to uncommitted data, and data changing between reads.

A balance must be achieved for maximum concurrency of all processes. Many controls in DB2 allow you to achieve maximum concurrency while maintaining data integrity. These controls range from the ...

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