With this month’s topic being “locking, concurrency and waits”, it may not be a bad time to review some of the locking basics. It might help your junior colleagues or your developers to get a better understanding.
Steve Thomas of CA Technologies presents a great introduction into the world of locks, latches, claims and drains. A must see for all developers working wit Db2 for z/OS as well as all DBAs wanting to refresh their knowledge.
Starting in Db2 Version 22.214.171.124, a new feature called 'DB2_AVOID_LOCK_ESCALATION' provides control over lock escalation behaviour. The feature is configured through a dynamic (no instance recycling needed) registry variable:
A singleton SELECT - is this always the best solution for readability and performance? The article discusses a simple scenario, that shows that a singleton SELECT can result in surprising application behavior if not used properly.
A good application should be a good citizen in the environment it is living in. Applications must also cope with situations where some of the actions (like updating rows) may fail because of other applications doing the same task.