Chapter 29. DB2 Resource Governing

IN THIS CHAPTER

• The Resource Limit Facility

• The QMF Governor

In addition to performance monitoring and tuning, actively controlling certain types of SQL can be beneficial. For example, consider a critical decision support query that retrieves hundreds, thousands, or even millions of rows from DB2 tables. If the query is well-planned, the designer will have a good idea of the amount of time necessary to satisfy the request.

As time goes on, however, the performance of the query could degrade for many reasons, such as unorganized indexes and table spaces, additional rows being returned, or outdated RUNSTATS . This degradation could affect the entire system because S-locks are being held and DB2 resources are being monopolized. It would be desirable, therefore, to disallow access on a prespecified basis when performance falls outside an acceptable range.