Explain tables
The Explain tables capture access plans when the Explain facility is activated.
The Explain tables must be created before Explain can
be invoked. You can create them using one of the following methods:
The Explain facility uses the following IDs as the schema
when qualifying Explain tables that it is populating:
- The session authorization ID for dynamic SQL
- The statement authorization ID for static SQL
- The SYSTOOLS schema if explain tables do not exist with the authorization ID schema
The population of the Explain tables by the Explain facility will not activate triggers or referential or check constraints. For example, if an insert trigger were defined on the EXPLAIN_INSTANCE table, and an eligible statement were explained, the trigger would not be activated.
To improve the performance of the Explain facility in a partitioned database system, it is recommended that the Explain tables be created in a single partition database partition group, preferably on the same database partition to which you will be connected when compiling the query.