Detector does not collect exceptions for GETPAGE activity as expected

Products

• Detector for DB2 for z/OS

Issue/Introduction

Even though a tool like SYSVIEW Performance Management Option for Db2 for z/OS (IDB2) shows a high number of e.g. Getpages that exceed
the specified threshold in Detector for Db2 for z/OS (PDT) no exceptions are collected.

Resolution

The reason could be that an exception in Detector is a single execution of an SQL statement while SYSVIEW Performance Management Option for Db2 accumulates for a number of fetches

Detector counts the exceptions based on the execution of a single SQL request or an OPEN, FETCH,CLOSE cycle. It resets & recalculates a new count for each OPEN/FETCH/CLOSE cycle.
Therefore, you cannot compare the threshold of e.g. GETPAGE 100,000 in Detector with the 500,000 Getpages in SYSVIEW Performance Management Option for Db2
for 250 Fetches - i.e. 2,000 on average.

You need to set a lower threshold in Detector.

The evaluation process in Detector is performed each time a cursor is opened. The GETPAGE & CPU time values for all 3 statements (OPEN, FETCH & CLOSE) are totaled to
determine whether or not a GETPAGE or CPU TIME exception occurred. The FETCH count is evaluated to determine whether or not a FETCH exception occurred.

If multiple cursors are opened within the Program, or if the same cursor is opened more than once within the Program, the above evaluation is done for each OPEN-> FETCH -> CLOSE cycle.

If the Program is executed again within the interval, the entire process starts again. However the totals for the new Program run are added to the summary totals, which are
displayed on the Standard Activity screens.