IBM 6.1.X manual Db2 reorgchk update statistics on table all

Models: 6.1.X

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While the Portal databases are configured for high capacity performance, various tuning adjustments may be necessary from time to time. Typically these tuning needs are based on the volume of database traffic and the size of table populations.

Our database tuning settings is documented in the Portal Info Center under ‘Creating Remote Database’ section.

D B 2 O N Z / O S S E T U P

After transferring the database tables, first Identify what tables need to be reorganized.

Perform a re-org check to improve performance.

Run the EJPSDBTC job after database transfer. This job contains the DB2 check and RUNSTATS utility for the JCR, Likemind and Feedback database.

For details on re-org DB2 database, visit WebSphere Portal Info Center. Create a Re-org job to re-org all table spaces in WPSDBJCR database.

R E C O M M E N D E D D A T A B A S E M A I N T E N A N C E F O R D B 2 L U W

Two of the database attributes, which DB2 relies upon to perform optimally, are the database catalog statistics and the physical organization of the data in the tables. Catalog statistics should be recomputed periodically during the life of the database, particularly after periods of heavy data modifications (inserts, updates, and deletes) such as a population phase. Due to the heavy contention of computing these statistics, we recommend performing this maintenance during off hours, periods of low demand, or when the portal is off-line. The DB2 runstats command is used to count and record the statistical details about tables, indexes and columns. We have used two techniques in our environment to recompute these statistics. The form we recommend is:

db2 runstats on table tableschema.tablename on all columns with distribution on all columns and sampled detailed indexes all allow write access

These options allow the optimizer to determine optimal access plans for complex SQL.

A simpler, more convenient technique for recomputing catalog statistics is:

db2 reorgchk update statistics on table all

Not only does this command count and record some of the same catalog statistics, it also produces a report that can be reviewed to identify table organization issues. However, we have found instances where this produces insufficient information for the

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W E BS P HE R E P O R T AL V 6 . 1 T U N I N G G U I D E

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IBM 6.1.X manual Db2 reorgchk update statistics on table all