IBM Db2 - The Ultimate Database for Cloud, Analytics & Mobile
Welcome to this, the fifth in the series on DB2 Locking for Application Developers. So far, we’ve covered a lot of ground, including the ACID properties of database transaction, the locking semantics implemented by DB2 – lock size, lock mode and lock duration – and issues such as lock contention and lock escalation, all with a view to understanding how data integrity and application performance depend on an effective partnership between DB2 and the application.
The next stage in this journey takes in the four isolation levels supported by DB2 (RR, RS, CS and UR), and the way they provide differing degrees of compromise between isolation (remember, the isolation property specifies that “all transactions must be executed, from a data point of view, as though no other transactions are being executed at the same time”) and concurrency – multiple transactions potentially accessing the same data running alongside each other.
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