PI92586: AE PI86134 FIX COMPLETION

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• AE PI86134 fix completion
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * AE PI86134 FIX COMPLETION                                    *
  * All users of DB2 11 or 12 for z/OS                           *
  * who run queries with an OPTIMIZE FOR                         *
  * 1 ROW or FETCH FIRST 1 ROW ONLY clause.                      *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * AE PI86134 FIX COMPLETION                                    *
  * For queries with an OPTIMIZE FOR 1 ROW                       *
  * or FETCH FIRST 1 ROW ONLY clause, DB2                        *
  * may choose sparse index to access                            *
  * the inner table when there are index                         *
  * plans available with good matching                           *
  * predicates. It may cause a query                             *
  * performance problem.                                         *
  *                                                              *
  * SQLACCESSPATH SQLFFNR                                        *
  * SQLOFNR SQLSPARSEINDEX                                       *
  * SPARSEINDEX SQLPERFORMANCE                                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available                          *
  ****************************************************************
  AE PI86134 FIX COMPLETION
  For queries with an OPTIMIZE FOR 1 ROW or FETCH FIRST 1 ROW
  ONLY clause, DB2 may choose sparse index to access the inner
  table when there are index plans available with good matching
  predicates.
  
  Compared with an index plan with good matching predicates, the
  sparse index plan cannot fetch the first several rows
  as efficiently. Therefore it should not get a cost reduction
  for the OPTIMIZE FOR 1 ROW or FETCH FIRST 1 ROW ONLY
  clause.
  

Problem conclusion

• AE PI86134 FIX COMPLETION
  The problem of the incorrect cost reduction for a sparse index
  plan is fixed by recognizing that the index plan with good
  matching predicates exists.
  

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:

  UI54123 UI54124

Modules/Macros

• DSNXOCSC
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI54123

     UP18/03/16 P F803

• RB10 PSY UI54124

     UP18/03/17 P F803

Fix is available

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