PI72800: INCORRECT FILTER FACTOR FOR PARTITION KEY OF VOLATILE TABLE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• DB2 may calculate a incorrect filter factor for using BETWEEN
  and RANGE predicates, when a volatile table is defined as
  partitioned with one limit key.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of DB2 11 for z/OS who have                        *
  * queries that include more than one range                     *
  * predicate on the same column of a volatile                   *
  * table                                                        *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * DB2 can underestimate the compound                           *
  *  filter factor of two range predicates                       *
  *  on the same column of a volatile table                      *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  If a volatile table has more than one local range predicate on
  
  the same column, and one range filter factor is calculated by
  
  one method while the other range filter factor is calculated
  
  by a different method, DB2 could underestimate the compound
  
  filter factor of the two range predicates if the sum of the
  
  two range filter factors is less than 1.
  
  
  
  Example SQL:
  
  SELECT * FROM T1
  
  WHERE T1.C1 > 0
  
  AND T1.C1 < ?;
  
  
  
  If table T1 is a volatile table, and the sum of the filter
  
  factors for the two range predicates is less than 1, DB2 11
  
  will get 1/tablecard as the compound filter factor of the
  
  two range predicates.
  
  
  
  Additional Keywords:
  
  SQLPERFORMANCE SQLACCESSPATH FILTERFACTOR SQLRANGE
  

Problem conclusion

• Code is updated to get a more reasonable compound filter factor
  for the problem above.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UI43588

Modules/Macros

• DSNXOCCF
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI43588

     UP17/01/13 P F701

Fix is available

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