IT15056: DB2 MIGHT PRODUCE INCORRECT RESULT WHEN EXECUTING QUERY WITH UNION AND MULTIPLE BASE TABLES

DB2 Version 10.1 Fix Pack 6 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• DB2 might produce wrong result if the following conditions are
  satisfied:
  1) The query has two or more tables
  2) The query has one or more UNION ALL
  3) There is a distinct on one of the tables
  4) All the tables are joined to the UNION ALL
  5) The UNION ALL has one or more branches returning only one row
  

Local fix

• Reduce query optimization to 1.
              db2 "SET CURRENT QUERY OPTIMIZATION 1";
              db2 <query to execute>
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * ALL                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to DB2 10.1 Fix Pack 6                               *
  ****************************************************************
  

Problem conclusion

• First fixed in DB2 10.1 Fix Pack 6
  

Temporary fix

Comments

APAR Information

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

  IT15033

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

Fix information

• Fixed component name

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels