Description of Data Space Activity Statistics and how to clear.

Resolving The Problem

This document describes the meaning of data space activity statistics.

Statistics are kept on database files but the descriptions of those statistics are not easily obtainable. The output from a DSPFD command to a screen actually goes to a spooled file first, and then it is displayed to the screen, so no help text is available.

The description of these fields can be obtained in the API Reference manual and in the Operations Navigator help text. The meanings are also listed here:

Insert Operations
Displays the number of rows inserted into the member since the last restart. This count does not reflect rows added to a member on behalf of a single entry copy instruction. Applying journal entries that result in inserts will affect this count.

Update Operations
Displays the number of rows updated in the member since the last restart. Updates performed on the member as a result of the set null and set default referential constraint rules will affect this count. Applying journal entries that result in updates will affect this count. Update operations that occur during rollback will also affect this count.

Delete Operations
Displays the number of rows deleted from the member since the last restart. Delete operations performed on this member as a result of the cascade referential constraint rule will affect this count. Applying journal entries that result in delete operations will affect this count. Delete operations that occur during rollback will also affect this count.

Logical Reads
Displays the number of logical read requests that have been on entries in the member since the last restart. This count reflects read requests issued regardless of whether a physical read request was actually performed. Rollback operations will affect this count. Note that Logical Reads is the number of Logical I/O requests made by DB2 for the physical file (or table).

Physical Reads
Displays the number of read requests that resulted in actual physical I/O requests on entries in the member since the last restart. Logical read requests do not necessarily result in a physical read request. Rollback operations will affect this count. Note that Physical Reads is the actual number of Physical I/O operations performed to satisfy the Logical I/O requests. DB2 might have done a logical I/O request, but there's no physical I/O operation performed because that part of the file was already in memory.

Clear Operations
Displays the number of times the member has been cleared since the last restart.

Index Builds/Rebuilds
Displays the number of access paths, both permanent and temporary, that have been built over this member since the last restart.

Reorganize Operations
Displays the number of times that the member has been reorganized since the last restart.

Full Opens
Displays the number of open operations performed on the member since the last restart.

Full Closes
Displays the number of close operations performed on the member since the last restart.

Rows Rejected by Key Selection
Displays the number of rows that were rejected by key row selection in open operations that are associated with the member.

Rows Rejected by Non-Key Selection
Displays the number of rows that were rejected by the non-key row selection in open operations that are associated with the member.

Rows Rejected by GROUP BY HAVING Selection
Displays the number of rows that were rejected by the GROUP BY HAVING selection in open operations that are associated with this member.

Distinct Valid Indexes
Displays the number of distinct valid indexes built over this member.

Distinct Invalid Indexes
Displays the number of distinct invalid indexes built over this member.

Additional statistical information has been added at R530 and later releases.

There are two methods to clear the Data Space Activity Statistics:

Method 1

1. Save the file
2. Delete the file
3. Restore the file

The statistics will be cleared. It does not clear them out if you do not delete the file first.

Method 2

IPL the system.