You can use the no-charge query-tuning features improve
the performance of SQL statements in applications that access DB2® for Linux, UNIX,
and Windows and DB2 for z/OS®.
You can format SQL statements so that they are easier to read, generate
visual representations of access plans, and get recommendations for
collecting statistics on the objects that a statement references.
You can also generate a report that summarizes information about the
access plan and includes the recommendations.
About this task
The no-charge features are so-called because they do not
require an active license for IBM® InfoSphere® Optim™ Query Workload Tuner, Version 3.1 or
3.1.1 on the DB2 databases and
subsystems that you tune SQL statements for. These features are a
subset of the features that are available in InfoSphere Optim Query
Workload Tuner. For a comparison of the no-charge features and the
features that are in that product, see Features by product.
Procedure
In most cases, to tune an SQL statement with the no-charge
query-tuning features in the Query Tuner Workflow Assistant,
you can follow these steps.
- Capture the SQL statement that you want to tune. See Locations
from which you can capture an SQL statement for single-query tuning.
- Format the SQL statement to make it easier to read and
comprehend. Seeing a formatted version of the SQL statement
can lead to insights that are not as apparent with the unformatted
version. See Formatting SQL statements.
- Analyze the access plan graph for the SQL statement to
find out how DB2 accesses data
in the objects that the statement references. See Generating visual representations of access plans.
- Run the Statistics Advisor and follow its recommendations
to ensure that the DB2 optimizer
has the most current and most important statistics. See Collecting statistics.