Filter
Top Products
18
WEBSPHERE PORTAL V6.1 TUNING GUIDE
optimizer to select an efficient access plan for complex SQL, particularly for queries of
the JCR database.
We have determined a technique that has the same convenience of the reorgchk
command and provides the detailed statistics preferred by the optimizer.
db2 -x -r "runstats.db2" "select rtrim(concat('runstats on table
',concat(rtrim(tabSchema),concat('.',concat(rtrim(tabname),' on all
columns with distribution on all columns and sampled detailed indexes
all allow write access'))))) from syscat.tables where type='T'"
db2 -v -f "runstats.db2"
The first command is used to create a file, runstats.db2, which contains all of the
runstats commands for all of the tables. The second command uses the db2 command
processor to run these commands.
To determine which tables might benefit from reorganization, we use the command:
db2 reorgchk current statistics on table all > "reorgchk.txt"
For those tables which require reorganization, we use the command:
db2 reorg table tableschema.tablename
to reorganize the table based upon its primary key.
You should also ensure that your database servers have adequate numbers of disks.
Multiple disks allow for better throughput by the database engine. Throughput is also
improved by separating the database logs onto separate physical devices from the
database.
You should ensure that the database parameter MaxAppls is greater than the total
number of connections for both the datasource and the session manager for each
WebSphere Portal application server instance. If MaxAppls is not large enough, you will
see exceptions in your connection pools.
You should use System Managed Storage (SMS) for temporary table spaces to benefit
complex SQL which require temporary tables to compute their result sets. This saves
time in buffer writes and improves disk utilization.
Database performance is very important for obtaining good performance from
WebSphere Portal. The maintenance tasks and practices mentioned here were found
to be critical to the performance and correct operation of WebSphere Portal in our lab
environment. Additional database maintenance and tuning may be needed in your
production environments. For further information on DB2 administration and tuning,
refer to the DB2 Information Center.