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WEBSPHERE PORTAL V6.1 TUNING GUIDE
RECO MMEND ED ORAC LE D ATABASE MAINT ENANCE
Optimizer statistics are a collection of data about the database and the objects in the
database, these statistics are used by the query optimizer to choose the best execution
plan for each SQL statement. Because the objects in a database can be constantly
changing, statistics must be regularly updated so that they accurately describe these
database objects, particularly after periods of heavy data modifications (inserts,
updates, and deletes) such as a population phase. We have used the following
commands in our environment to recompute these statistics:
execute
dbms_stats.gather_database_stats(dbms_stats.auto_sample_size,
method_opt=>'FOR ALL INDEXED COLUMNS SIZE AUTO',cascade=>TRUE);
O T H E R D A T A B A S E C O N S I D E R A T I O N S
WebSphere Portal maintains some information about users in its database tables, which
grow when a user first logs in. We were interested in the steady-state performance of
WebSphere Portal, not the performance of a user’s first login to the site. Therefore our
performance evaluates after all users logged in at least one time.
One of the most important database tuning factors is bufferpool sizing. It is important to
evaluate the database's physical versus logical reads and size the bufferpools to achieve as
much as a 95% logical read rate if possible.