Interpreting db2exfmt output

In the previous recipe, we discussed how to use different explain utilities. db2exfmt is the most commonly-used utility for troubleshooting a performance problem. This utility gives very detailed information captured in EXPLAIN tables in the form of an ASCII text report. This report contains textual information, as well as the access plan in a graphical format, which is extremely useful for query analysis. In this recipe, we will discuss how to interpret the results from the db2exfmt utility.

How to do it...

As mentioned in the previous recipe, the output of the db2exfmt tool contains very detailed information about the query execution plan. In this section, we will discuss how to interpret each section.

1. 1. Verifying the database information: The top section of the db2exfmt output contains DB2 version information, and the time when the db2exfmt tool was run.

2. 2. Check the database context area: This section contains the configuration parameter values that have...