Overview of RunTimeStatistics

When RUNTIMESTATISTICS is turned on for a connection, Derby maintains information about the execution plan for each statement executed within the connection (except for COMMIT) until the attribute is turned off.

For the most recently executed query, RUNTIMESTATISTICS returns information about:

The length of the compile time and the execute time
This can help in benchmarking queries.
The statement execution plan
This is a description of result set nodes, whether an index was used, what the join order was, how many rows qualified at each node, and how much time was spent in each node. This information can help you determine whether you need to add indexes or rewrite queries.

The exact details presented, as well as the format of presentation, can change. There are two techniques for retrieving the RUNTIMESTATISTICS information:

Call SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS, which retrieves the RUNTIMESTATISTICS information as formatted text.
Before executing your statements, call SYSCS_UTIL.SYSCS_SET_XPLAIN_SCHEMA, which causes Derby to store the RUNTIMESTATISTICS information in the SYSXPLAIN database tables. These tables can be queried later to retrieve the data.