An Introduction to db2mon
The monitoring table functions are the best way to view Db2 monitoring statistics. Being able to use SQL to query the monitoring data is great but most of the metrics are cumulative since database activation. We created db2mon to perform deltas and produce reports.
This is part 2 in the series that focuses on improving performance in Db2 Warehouse databases. The first part gave some background and discussed some basic concepts relevant to query optimization in the context of the Db2 column engine.
Part 2 : Identifying Costly Operations + Improving Joins
Since the beginning, I/O has been one of the main determining factors for overall performance. I/O can easily surpass all other considerations, particularly if an SQL statement asks for a very large result or a missing index causes the scan of a very large table.
In this article, inspired from his presentation in IDUG EMEA 2019, Pawel Hryb talks on possibilities and strategies when doing complex SQL tuning in Db2 for z/OS: Where to begin, how to dissect a complex query, sources of information to try and how to proceed when you need a deeper investigation.
In this article, Brian Laube shows how we can solve a real-life performance problem by copying access path information from one environment to another one and then using it as an optimization hint.