6. DATA SOURCES › 6.4 Query CP Parallelism Considerations › 6.4.1 Collecting Query CP Parallelism Information

6.4.1 Collecting Query CP Parallelism Information

The CA MICS Analyzer Option for DB2 collects application
program information from the DB2 SMF type 101 Accounting
Trace Record (IFCID 0003 or IFCID 0239).  Applications using
CP parallelism generate multiple records, each one containing
a portion of the total query consumptions.

Parallel tasks, by default, result in additional accounting
trace records because, in addition to the record for the
parent query, a record is produced for each parallel child
task. A DB2 parameter, PTASKROL=YES, results in the
consolidation of the child records into a single rollup
record, thereby reducing the number of SMF type 101
accounting trace records to one for the parent and a rollup
record for the parallel child tasks.

The rollup record is written at deallocation time, along with
the parent task record.  For example, if a query generates 6
additional parallel subtasks (with PTASKROL set to YES),
instead of writing 7 SMF records (1 for the parent task and 6
for the child tasks), only two will be created: the parent
task and the child tasks' summary.

Although both records are written at deallocation time and
contain common identification information, the rollup summary
record is not a duplicate of the parent record.  Some fields
in the rollup record are identical or already included in the
parent record, but most of the information used for
accounting and performance analysis must be added to parent
task's metrics to get a complete picture.  The fields
containing rollup data were described in IBM APARs PQ10864,
PQ22451, and further qualified in PQ41012.

The CA MICS Analyzer Option for DB2 reads and stores
information from both records, allowing a complete
application or user resource accounting, as well as a
detailed DB2 performance analysis of parallel processing.
For more information, see Section 6.4.2, Parallel Tasks Data
Analysis.