Monitoring the access path with Explain

Online Monitor Explain provides a real-time analysis of the access path methods that are chosen by DB2® for a given SQL statement. You can also modify the SQL statement text and reexplain it. This provides you with the ability to tune a Db2 subsystem while you are online.

This topic describes how to select the SQL statement you want to explain from within the Online Monitor or from within an ISPF/PDF editor, the authorization required to use Explain, performance considerations, tuning advice, and the Db2 Explain Output panel.

Online Monitor Explain is based on DB2's SQL Explain function. However, it translates the more important PLAN_TABLE codes into full English sentences, so you do not need to know the values and columns of the PLAN_TABLE. In addition, Online Monitor Explain provides direct access to related catalog information (the catalog statistics of the tables and indexes that are used in the SQL statement).