Playing with cardinality and selectivity on predicates is not a common trick, though Joe Geller, David Simpson and Tony Andrews demystify it so that you can start playing with its intricacies and give a boost to the Optimizer.
En este artículo, Javier Estrada Benavides nos ofrece un acercamiento a una de las características nuevas de Db2 12 para z/OS: Dynamic SQL plan stability.
One of the most common maintenance activities performed on a Db2 LUW database is running Runstats on tables and indexes. Accurate database statistics are vital for the Db2 Optimizer to produce the most optimal plans.
Starting in Db2 Version 126.96.36.199, 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:
It's inevitable that you see a couple of DB2 fix packs every year and place the readme document in a drawer somewhere for perusal later when you are not busy. While the fix packs may contain fixes there are sometimes a few enhancements buried in the fine print.