PH21189: TOLERATE INDEXES ON DECFLOAT COLUMN

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The Db2 V12 Function level 505 introduces improvements to the
  support for DECFLOAT columns to improve performance of mission
  critical applications. These improvements include the ability to
   specify DECFLOAT columns in an index and as a key in a primary
  or unique key.
  
  Db2 HPU exploits indexes for the index scan feature that may be
  triggered to process the ORDER clause of an unload statement. As
  Db2 HPU does not support indexes with DECFLOAT columns, it may
  fail when processing a logical unload with an ORDER clause which
  order criterion involves a DECFLOAT column and matches the key
  of an index on the involved table if the index scan feature is
  enable.
  

Local fix

• If the problem occurs, it can be solved by disabling the index
  scan feature by adding the INDEXSCAN NO option to the UNLOAD
  statement.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of Db2 High Performance Unload         *
  *                 for z/OS                                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: The Db2 V12 Function level 505          *
  *                      introduces improvements to the support  *
  *                      for DECFLOAT columns to improve         *
  *                      performance of mission critical         *
  *                      applications. These improvements        *
  *                      include the ability to specify DECFLOAT *
  *                      columns in an index and as a key in a   *
  *                      primary or unique key.                  *
  *                                                              *
  *                      Db2 HPU exploits indexes for the index  *
  *                      scan feature that may be triggered to   *
  *                      process the ORDER clause of an unload   *
  *                      statement. The index scan feature does  *
  *                      not support indexes. Any attempt to use *
  *                      it in such a case leads to inefficient  *
  *                      index scan feature reported the         *
  *                      statistics bloc in the SYSPRINT dataset *
  *                      by IXSC 0% which means the index scan   *
  *                      feature is uselessly run and reduces    *
  *                      Db2 HPU performance where it should     *
  *                      increase it, As a consequence, the      *
  *                      index scan feature should automatically *
  *                      e disabled whenever the involved        *
  *                      clustering index has a key involving a  *
  *                      DECFLOAT column.                        *
  ****************************************************************
  * RECOMMENDATION: Apply the PTF.                               *
  ****************************************************************
  Disable indexscan when an index key involved DECFLOAT type
  

Problem conclusion

• Code has been changed to fix this problem.
  

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:

  UI68180

Modules/Macros

• INZ$$PRM INZTDSC  INZTVAR  INZUTIB1 INZUTIB2 INZUTILC INZUTILK
  INZUTILL
  

Fix information

• Fixed component name

  DB2 HI PERF UNL

• Fixed component ID

  5697F4400

Applicable component levels

• R430 PSY UI68180

     UP20/03/13 P F003

• R510 PSY UI68215

     UP20/03/18 P F003

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.