PI65342: DISABLE 'FOR READ ONLY' CLAUSE SUPPORT

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• When the data to be retrieved by DB2 is only meant for reading,
  a good practice consists in specifying the FOR READ ONLY clause
  which allows DB2 to optimize its behavior and performance when
  processing the involved SELECT statement. DB2 HPU implements
  this good practice by adding the FOR READ ONLY clause to the
  SELECT statements specified in the UNLOAD command.
  
  However, in very rare situations, adding the FOR READ ONLY
  clause unexpectedly causes DB2 to choose an irrelevant access
  path thus leading to decreased performance.
  
  To circumvent this access path issue, DB2 HPU should be fitted
  with a parameter that allows to request the FOR READ ONLY clause
  not to be added.
  
  Please contact IBM Support for details if interested in this
  feature.
  
  PB45878
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of IBM DB2 High Performance Unload     *
  *                 z/OS.                                        *
  ****************************************************************
  * PROBLEM DESCRIPTION: When the data to be retrieved by DB2 is *
  *                      only meant for reading, a good          *
  *                      practice consists in specifying the     *
  *                      FOR READ ONLY clause which allows DB2   *
  *                      to optimize its behavior and            *
  *                      performance when processing the         *
  *                      involved SELECT statement. DB2 HPU      *
  *                      implements this good practise by adding *
  *                      the FOR READ ONLY clause to the SELECT  *
  *                      statements specified in the UNLOAD      *
  *                      command.                                *
  *                      However, in very rare situations,       *
  *                      adding the FOR READ ONLY clause         *
  *                      unexpectedly causes DB2 to choose an    *
  *                      irrelevant access path thus leading to  *
  *                      decreased performance.                  *
  *                      To circumvent this access path issue,   *
  *                      DB2 HPU should be fitted with a         *
  *                      parameter that allows to request the    *
  *                      FOR READ ONLY clause not to be added.   *
  *                      pb 45878                                *
  ****************************************************************
  * RECOMMENDATION: APPLY the PTF.                               *
  ****************************************************************
  N/A (enhancement).
  

Problem conclusion

Temporary fix

Comments

• APPLY the PTF.
  

APAR Information

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

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

Modules/Macros

•    INZCRXSM INZCRXSQ INZUTILK
  

Fix information

• Fixed component name

  DB2 HI PERF UNL

• Fixed component ID

  5697F4400

Applicable component levels

• R430 PSY UI39950

     UP16/08/12 P F608

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.