IT23261: INCORRECT RESULTS WITH AGGREGATION ON OUTER JOINED TABLE WITH FOREIGN KEY ON NULL PRODUCING TABLE

Db2 Version 11.1 Mod 3 Fix Pack 3 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod3 Fix Pack3 iFix001 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod3 Fix Pack3 iFix002 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 6 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 5 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 7 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• Incorrect results might be observed from queries:
  1. contain at least one of these aggregations:
     COUNT(*), COUNT_BIG(*), COUNT(CONSTANT), COUNT_BIG(CONSTANT),
  SUM(CONSTANT), MAX(CONSTANT) and MIN(CONSTANT)
  2. the aggregations are on outer joined tables;
  3. a foreign key on the NULL producing table of the outer join
  references the primary key on the table at the other side of the
  outer join;
  
  An example query:
  SELECT T1.X, COUNT (*) as c1 from TABLE_1 T1 left join TABLE_2
  T2 on (T1.X = T2.Y) group by T1.X
  
  whereas TABLE_1.X is the primary key and TABLE_2.Y is a foreign
  key referencing the primary key TABLE_1.X
  

Local fix

• Set OPT level 1 by adding the following text after the
  problematic query:
  /* <OPTGUIDELINES>
       <QRYOPT VALUE='1'/>
  </OPTGUIDELINES> */
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Db2 users                                                *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Db2 11.1.3.3 or later.                            *
  ****************************************************************
  

Problem conclusion

• First fixed in Db2 11.1.3.3
  

Temporary fix

Comments

APAR Information

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

  IT23260

• 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 PSN

     UP

• RB10 PSY

     UP