PI64234: INEFFICIENT ACCESS PATH INVOLVING RANGE LIST PREDICATE(S)

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• A Range list access path could be chosen when a more
  efficient access path is available.
  
  Additional symptoms and search keywords:
  SQLPERFORMANCE SQLACCESSPATH SQLRANGELIST
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: DB2 11 for z/OS users who have a query with  *
  *                 OR predicates that can map to a single       *
  *                 index.                                       *
  ****************************************************************
  * PROBLEM DESCRIPTION: DB2 may favor range list index scan     *
  *                      with data page access over index access *
  *                      when the index access plan is more      *
  *                      efficient but with higher uncertainty.  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  DB2 may favor range list index scan with data page access over
  index access when the index access plan is more efficient but
  with higher uncertainty.
  
  For example,
  
  SELECT C4
  FROM T1
  WHERE  C1 > ?
    AND (C2 > ?
     OR (C2 = ?
    AND  C3 > ?))
  
  
  If an index IX1 is defined on (C1) and another index IX2 is
  defined on (C2, C3), DB2 may favor a range list index scan
  using IX1 even though an index access using IX2 is more
  efficient.
  
  
  Additional Keywords:
  SQLACCESSPATH  SQLPERFORMANCE  SQLRANGELIST SQLOR
  

Problem conclusion

• Code has been modified to solve the problem described as above.
  DB2 will not favor range list index scan with data page access
  over index access when the index access plan is more
  efficient but with higher uncertainty.
  

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:

  UI40644

Modules/Macros

• DSNXOCSC
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RB10 PSY UI40644

     UP16/09/21 P F609

Fix is available

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