DB2 graphic QMF Version 8

Sample exit routine

The sample exit routine is named RAARXQA and it performs several operations on the raw analysis data as received from the analysis engine. Refer to the comments within these exits for details on the processes and for a list of the incoming parameters, the names of the variables, and their meanings.

Set CANFLG variable

To cancel a query, set the CANFLG variable to the character string CANCEL. Any other value allows the query to continue running. For example, if a table is being accessed at a time of day when it is restricted, the exit routine can set this flag, as described in Step 5, "Call Exit Routine," to cancel the query.

To pass the variable value back to Query Analyzer, the exit routine must VPUT the variable into the shared variable pool.

ISPEXEC VPUT (CANFLG) SHARED

You can add threshold logic, such as, logic that will cancel a query if more than one table is accessed and no indexes are used.

Set AAQARM variable

The exit routine can pass back the number of rows to fetch before canceling the query. This allows each user the ability to minimize resource consumption by limiting the number of rows fetched for each query. To pass the variable value back to Query Analyzer, the exit routine must also VPUT the variable into the shared variable pool.

ISPEXEC VPUT (AAQARM) SHARED

Set analysis output variables

The exit routine must VPUT all variables that will be displayed on the output panel. In the sample exit, the variables QAP1 through QAP29 are VPUT to the shared pool.

ISPEXEC VPUT (QAP1 , QAP2 , QAP3 , QAP4 , QAP5 ,
              QAP6 , QAP7 , QAP8 , QAP9 , QAP10,
              QAP11, QAP12, QAP13, QAP14, QAP15,
              QAP16, QAP17, QAP18, QAP19) SHARED
ISPEXEC VPUT (QAP20, QAP21, QAP22, QAP23, QAP24,
              QAP25, QAP26, QAP27, QAP28, QAP29) SHARED

The analysis output variables and their descriptions are presented in the table below.

Variable Description
QAP1 Number of Query blocks
QAP2 Number of Tables Referenced
QAP3 Join Methods
QAP4 Access Types
QAP5 Number of Index Only scans
QAP6 DB2 Sorting
QAP7 Parallelism Modes
QAP8 Highest Access Degree
QAP9 Number of Page Range Screens
QAP10 Join Types
QAP11 Prefetch Types
QAP12 Minimum row count
QAP13 Maximum row count
QAP14 Average row count
QAP15 Minimum CPU time
QAP16 Maximum CPU time
QAP17 Average CPU time
QAP18 Number of Matching Index scans
QAP19 Column Functions Evaluation Types
QAP20 Is access through an index?
QAP21 Is access through more than one index?
Variable Description
QAP22 How many indexes use matching columns?
QAP23 Is the query satisfied using only an index?
QAP24 Are scans limited to certain partitions?
QAP25 What kind of prefetching is done?
QAP26 Is data accessed/processed in parallel?
QAP27 Are sorts performed?
QAP28 Are joins present in query?
QAP29 When are column functions evaluated?


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timestamp Last updated: March, 2004