Updates to a database structure (such as by altering a
table, creating an index, or dropping an index) and modifications
to user authorization can change the access plan for the SQL statements
and affect performance.
In this scenario, you can compare access plans for SQL statements
from packages to determine if performance has regressed or improved.
Tip: You should specify as the source a collection
(that is, a group of packages) that contains the access plan and packages
from before the database structure or user authorization was changed.
You should specify as the target a collection that contains
the access plans and packages from after the database structure or
user authorization was changed.