Concurrency and Transaction Management

Although concurrency and transaction management are in fact two separate topics, they go hand in hand when considered in terms of database programming strategies. DB2 must ensure the integrity of your data and query results by restricting access to table data by applying row and table locks. This chapter explains how this is done using isolation levels, as well as how transactions actually define when locks will be held.

When applications must wait for a lock before a query can be executed, this is known as lock-wait. Lock-wait occurs to guarantee accuracy of results and to maintain the integrity of the underlying data. Thus, in many cases, applications may experience valid periods of lock-wait.

Almost all ...

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