Tuning of SQL queries requires understanding why DB2 chose a particular access path and determining whether or not that access path should perform as expected. The key to this is understanding what filter factors are, how they are used by the Optimizer and how to get DB2 to better estimate them,
When you exchange XML documents between different systems or applications, you may need a construct that ensures your applications will “understand” the XML documents that are being exchanged. And this is where XML schema comes into a play!
Let’s start this discussion candidly – I am a big fan of the FETCH FIRST n ROWS ONLY clause coded in a SQL statement. That assertion will require some clarification, since there are some valid use cases, and others that make little sense. Regardless, I will try not to over-complicate the discussion.
In February 2016 the DB2 12 Editorial Committee was formed, comprised of volunteers from IDUG’s worldwide community of DB2 users and consultants. This White Paper contains their findings, including practical experiences and independent evaluations of the new features.