IT31208: INCORRECT RESULT WHEN USING TWICE JOIN WITH THE SAME TABLE WITH GROUP BY

Db2 Version 11.1 Mod 4 Fix Pack 6 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 6 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• Queries with following characteristic may return incorrect
  results:
  - GROUP BY query over base tables
  - FROM references the same table more than once using aliases
  - multiple columns in GROUP BY clause referencing same table
  using different aliases
  - one of GB column is primary/unique key and one column comes
  from different alias of the same table
  - PK column is referenced in SELECT, while column from different
  alias is not referenced in SELECT
  
  Sample query (tab1.id is primary key):
  SELECT a.id FROM tab1 a, tab1 b WHERE a.c1 = b.c1 GROUP BY a.id,
  b.c2 HAVING COUNT(*) > 1
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * SQL USING TWICE JOIN WITH THE SAME TABLE WITH                *
  * GROUP BY                                                     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * See Error Description                                        *
  ****************************************************************
  

Problem conclusion

• See Error Description
  

Temporary fix

Comments

APAR Information

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

  IT31207

• 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

• RB10 PSY

     UP