With the SQL OLAP RANK and DENSE_RANK functions being around for a while in SQL programming, it is quite easy to query for the TOP XX from data.
This article is one in a series that focuses on improving performance in Db2 Warehouse. The first part provides some background information and lays out the first and most important aspect of query optimization, namely, cardinality estimation or estimating the number of rows in an execution plan.
I spend every day of my life since 1990 as a Db2 DBA both on Db2 for z/OS and Db2 for LUW. During that time, I’ve collected a lot of knowledge that makes my job easier and gets easier and gets the answers to the developer’s questions in a timely fashion.
DB2 is particularly good at running complex query and analytical processing. Since all modern hardware contains multiple cores and CPUs, and many systems are composed of multiple machines, it is critical that DB2 run individual queries across all available computing resources.
Do you really understand what might change in your Db2 world as a result of moving to an encrypted database? To help avoid unpleasant surprises, here's a little cheat-sheet on things to consider before using Db2 Native Encryption.