PH29666: DB2 12 SERVICEABILITY FOR INFLUENCING ACCESS PATH SELECTION

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Db2 12 serviceability for influencing access path selection.
  For SQL statements with complex inner and outer joins, Db2 12
  uses an aggressive approach to reduce join work files. However,
  this approach may cause performance degradation in some cases.
  Keywords: SQLPERFORMANCE SQLACCESSPATH
    SQLJOIN SQLOUTER SQLOUTERJOIN
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Db2 V12 for z/OS users running SQL                       *
  * statements with complex inner and outer                      *
  * joins                                                        *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Db2 12 hidden zparm support for                              *
  * disabling aggressive approach to                             *
  * reduce join work files for SQL                               *
  * statements with complex inner and                            *
  * outer joins.                                                 *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available                          *
  ****************************************************************
  For SQL statements with complex inner and outer joins, Db2 12
  uses an aggressive approach to reduce join work files. With
  few exceptions, this aggressive approach should provide
  significant performance improvements. On the rare occasion
  that a regression does occur, IBM support may request for this
  new feature to be disabled. The hidden zparm should not be
  changed without consulting IBM support first.
  This is a serviceability enhancement to disable the aggressive
  approach.
  

Problem conclusion

• Serviceability APAR only.
  Keywords: SQLPERFORMANCE SQLACCESSPATH SQLOUTERJOIN SQLFULLJOIN
            SQLOUTER SQLFULL SQLJOIN SQLLEFTJOIN SQLLEFT
            SQLRIGHTJOIN SQLRIGHT
  

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:

  UI71877

Modules/Macros

• DSNXOMQB DSNDQWPZ DSNXOMPS DSNDSPRM DSN6SPRC
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI71877

     UP20/10/09 P F010

Fix is available

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