2. SQL/MF components
The System Monitor provides monitoring at the database level. At a defined interval,
the system monitor takes a “snapshot" of database resource usage and stores the
results in DB2 tables.
The Statement Monitor monitors the databases at the SQL statement level, by
recording the execution characteristics of every SQL statement submitted to the DB2
server.
The Governor controls DB2 resource consumption by users and packages.
The AutoPrep facility optimizes the use of dynamic SQL statements.
In a relational database, access to the data is determined by the database manager.
Inefficient access paths may result if SQL statements are poorly coded. Therefore,
monitoring at the SQL statement level is essential.
3. SQL/Monitoring Facility
Product Highlights
Statement monitoring
monitors all running SQL statements with unprecedented detail
saves the runtime statistics for every SQL statement executed
logs poorly performing statements in an exception table
provides application recording and benchmarking services
issues real time alerts when performance problems are detected
the Governor function monitors DB2 clients for resource usage and terminates users
that violate defined resource limits
the AutoPrep facility automatically replaces frequently used dynamic SQL statements
with prepped access
System Monitoring
performs database-wide measurements for the DB2 subsystems:
interpreter (RDS)
I/O manager (DBSS)
data spaces
lock manager
checkpoint agent
4. SQL/Monitoring Facility
Running Statement List
The running
statement list
shows all SQL
statements
executing in all
monitored
databases.
The list is ordered
by database and
descending SQL
cost.
Statements with an
excessive SQL cost
are highlighted.
5. SQL/Monitoring Facility
Running Statement Detail
Detail is available for all
statements in the
“running” list.
The detail screen shows:
the agent state
all run-time statistics
the statement text of all
dynamic and static
statements (with the
actual value of the host
variables)
the DB2 access path
actions allowed from the
detail screen
7. SQL/Monitoring Facility
Exception Logging
An installation may
define a number of
exception criteria in the
SQL/MF configuration
file.
When an SQL statement
exceeds one of these
exception limits during
its execution, it is
recorded in the SQL/MF
Exception table.
Exception criteria can
be specified as:
a maximum number of
I/O requests
a maximum response
time
a maximum lock wait
time
a maximum idle time
a defined range of
SQLCODEs
a "lock escalate" event
etc..
8. SQL/Monitoring Facility
Statement Statistics
When an SQL
statement completes
execution, SQL/MF
stores all statistics
recorded for the
statement in its
SQL_STATEMENTS
table.
This table records:
the text of the
statement
the statement’s
access path
the runtime statistics
for the last execution
By consulting this
table, the DBA can
always obtain the
monitor information for
the last execution of
every SQL statement.
9. SQL/Monitoring Facility
Statement Recorder
The SQL/MF Recorder
notes into the
Recorder file:
all SQL statements
with all execution
details
all DB2 checkpoints
all DB2 lockwait
events
The Recorder can be
enabled:
for designated users
or packages
for all users during a
specified period
To achieve acceptable
performance,
recording uses data
spaces.
Recorder List
Recorder Detail
10. SQL/Monitoring Facility
Statement Analysis
Every SQL statement
captured by the
monitor can be
forwarded to the
Analysis facility.
The facility performs a
DB2 EXPLAIN for the
statement and formats
the EXPLAIN output
into an easily readable
analysis report.
Then, the facility
analyzes the
statement’s predicate
and verifies it against
all performance rules
documented by IBM in
the “DB2 Performance
Tuning” manual.
When necessary,
warning messages are
inserted into the
analysis report.
11. SQL/Monitoring Facility
Notification Facility
Upon request, the notification facility will
alert a designated user when:
an SQL statement performs more than
a defined number of buffer lookups or
I/O requests
an SQL statement exceeds a defined
response time
a user session is idle for a defined
period
an SQL statement is in the lockwait
state for a defined period
a dynamic SQL statement exceeds a
defined SQL cost
NOTIFY BUFLOOK n
NOTIFY TOTIO n
NOTIFY RESPTIME n
NOTIFY IDLETIME n
NOTIFY LOCKTIME n
NOTIFY DYN_COST n
12. SQL/Monitoring Facility
Governor Facility
The Governor is a database-wide facility
that prevents uncontrolled resource
consumption by users and packages.
When defined resource limits are
exceeded, the Governor forces the
user off the database.
Resource maximums can be defined for:
I/O rate
lockhold time
statement response time
idle time
dynamic SQL statement cost
INCLUDE / EXCLUDE statements define
the users or packages subject to a
particular restriction.
The following restriction will prevent
ISQL users to perform more than
1000 I/O’s in one LUW
MAX_IO 1000
INCLUDE PROGRAM ARIISQL
13. SQL/Monitoring Facility
AutoPrep Facility
The purpose of the AutoPrep facility is to reduce the cost of dynamic SQL
statements.
Dynamic SQL implies that DB2 determines the access strategy before every
execution of the dynamic SQL. However, access path determination is a
costly process in terms of CPU usage and catalog contention.
Today, with increased PC database access, e-business and ERP applications,
dynamic SQL tends to become a performance bottleneck.
AutoPrep offers a solution by:
detecting frequently executed dynamic SQL commands
initiating a DB2 prep for these commands (in the AutoPrep server)
replacing the dynamic sequence with a static one that invokes the
generated package
The solution completely avoids path determination and its associated cost.
Benchmarks have shown that AutoPrep reduces CPU usage during dynamic
SQL with a factor 3 to 5.
14. SQL/Monitoring Facility
System Monitor
The SQL/MF System Monitor records
the global performance of DB2
databases.
The component runs in a dedicated
virtual machine and inspects all
monitored databases at an installation
defined sampling interval. The
sampled results are saved in the
System Monitor tables.
Monitoring is performed for several
aspects (classes) of database
performance:
System Class
Dataspaces Class
Buffer Pool Class
Package Class
DBspace Class
Storage Pool Class
Log Class
Agent Class
Lockwait Class
Connections Class
Checkpoint Class
18. SQL/Monitoring Facility
System Monitor - Checkpoint Counters
The extended counters report shows,
among other data:
the number of checkpoints during
the interval
the duration of each checkpoint
the checkpoint delay time, if any
