A release migration could be a DB2® version-to-version upgrade (such as migrating
from DB2 Version 9 for z/OS® to DB2 10 for z/OS)
or a DB2 maintenance level upgrade
(such as applying an APAR or a PTF). A release migration might introduce
new features and change the behavior of the DB2 SQL optimizer. Rebinding a DB2 package after a release migration might change
the access plan for the SQL statements and affect performance.
About this task
In this procedure, before you migrate to another release
or apply maintenance fixes, you create and explain a query workload
that contains the SQL statements that are in your application. Then,
you migrate or apply maintenance fixes. Finally, you create and explain
another query workload that contains the SQL statements in your application,
and compare the EXPLAIN snapshot for the first query workload to the
EXPLAIN snapshot for the second query workload.
Although
this procedure makes use of two separate query workloads, you can
create a single query workload, explain it, migrate or apply maintenance
fixes, and then explain the query workload again. You can then compare
the two EXPLAIN snapshots.
To identify and address changes to access plans due to
release migration or applying maintenance fixes: