Starting a summary monitor

You can start this monitor by right-clicking SQL Performance Monitors under the Database portion of the iSeries Navigator tree and selecting New > SQL Performance Monitor. In the monitor wizard, select Summary.

When you create a summary monitor, certain kinds of information are always collected. This information includes summary information, SQL statement information, and host variable information. You can also choose to collect the following types of information:

Table scans and arrival sequences

Select to include information about table scan data for the monitored jobs. Table scans of large tables can be time-consuming. If the SQL statement is long running, it may indicate that an index might be necessary to improve performance.

Indexes used

Select to include information about how indexes are used by monitored jobs. This information can be used to quickly tell if any of the permanent indexes were used to improve the performance of a query. Permanent indexes are typically necessary to achieve optimal query performance. This information can be used to determine how often a permanent index was used by in the statements that were monitored. Indexes that are never (or very rarely) used should probably be dropped to improve the performance of inserts updates and deletes to a table. Before dropping the index, you may want to determine if the index is being used by the query optimizer as a source of statistics.

Index creation

Select to include information about the creation of indexes by monitored jobs. Temporary indexes may need to be created for several reasons such as to perform a join, to support scrollable cursors, to implement ORDER BY or GROUP BY, and so on. The created indexes may only contain keys for rows that satisfy the query (such indexes are known as sparse indexes). In many cases, the index create may be perfectly normal and the most efficient way to perform the query. However, if the number of rows is large, or if the same index is repeatedly created, you may be able to create a permanent index to improve performance of this query. This may be true whether an index was advised.

Data sorts

Select to include information about data sorts that monitored jobs perform. Sorts of large result sets in an SQL statement may be a time consuming operation. In some cases, an index can be created that will eliminate the need for a sort.

Temporary file use

Select to include information about temporary files that monitored jobs created. Temporary results are sometimes necessary based on the SQL statement. If the result set inserted into a temporary result is large, you may want to investigate why the temporary result is necessary. In some cases, the SQL statement can be modified to eliminate the need for the temporary result. For example, if a cursor has an attribute of INSENSITIVE, a temporary result will be created. Eliminating the keyword INSENSITIVE will typically remove the need for the temporary result, but your application will then see changes as they are occur in the database tables.

Indexes considered

Select to include information about which indexes were considered for the monitored jobs. This information can help to determine if an index is used in the query. If an index was considered, but not used, you might need to rewrite the index or drop it. Before dropping the index, you may want to determine if the index is being used by the query optimizer as a source of statistics.

Subselect processing

Select to include information about subselect processing. This information can indicate which subquery in a complex SQL statement is the most expensive.

You can choose which jobs you want to monitor or choose to monitor all jobs. You can have multiple instances of monitors running on you system at one time. For summary monitors, only one monitor instance can be monitoring all jobs. Additionally, you cannot have two monitors monitoring the same job. When collecting information for all jobs, the monitor will collect on previously started jobs or new jobs started after the monitor is created. You can edit this list by selecting and removing jobs from the Selected jobs list.