Verify the performance of SQL applications

You can verify the performance of an SQL application by using commands.

The commands that can help you to verify performance are:

Display Job (DSPJOB)

You can use the Display Job (DSPJOB) command with the OPTION(*OPNF) parameter to show the indexes and tables being used by an application that is running in a job.

You can also use DSPJOB with the OPTION(*JOBLCK) parameter to analyze object and row lock contention. It displays the objects and rows that are locked and the name of the job holding the lock.

Specify the OPTION(*CMTCTL) parameter on the DSPJOB command to show the isolation level that the program is running, the number of rows being locked during a transaction, and the pending DDL functions. The isolation level displayed is the default isolation level. The actual isolation level, used for any SQL program, is specified on the COMMIT parameter of the CRTSQLxxx command.

Print SQL Information (PRTSQLINF)

The Print SQL Information (PRTSQLINF) command lets you print information about the embedded SQL statements in a program, SQL package, or service program. The information includes the SQL statements, the access plans used during the running of the statement, and a list of the command parameters used to precompile the source member for the object.

Start Database Monitor (STRDBMON)

You can use the Start Database Monitor (STRDBMON) command to capture to a file information about every SQL statement that runs.

Change Query Attribute (CHGQRYA)

You can use the Change Query Attribute (CHGQRYA) command to change the query attributes for the query optimizer. Among the attributes that can be changed by this command are the predictive query governor, parallelism, and the query options.

Start Debug (STRDBG)

You can use the Start Debug (STRDBG) command to put a job into debug mode and, optionally, add as many as 20 programs and 20 class files and 20 service programs to debug mode. It also specifies certain attributes of the debugging session. For example, it can specify whether database files in production libraries can be updated while in debug mode.