IT29981: DB2 MAY RETURN INCORRECT RESULTS WHEN EXECUTING IUD STATEMENTS CONTAINING A SUBQUERY WITH CORRELATION AND AGGREGATION

Db2 Version 11.1 Mod 4 Fix Pack 5 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 6 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• Db2 may return incorrect results when executing IUD statements
  containing a subquery with the following properties:
  
  - The subquery contains correlated predicates.
  - The subquery contains aggregation.
  - The subquery references another subquery or
  common-table-expression that returns unique records (for example
  via aggregation or DISTINCT).
  
  For example:
  
  insert into mytable3
    with mycte as (
      select mytable.c1 c1, mytable2.c1 c2
        from mytable, mytable2
        where mytable.c2 = mytable2.c2
        group by mytable.c1, mytable2.c1
      )
    select distinct c1
      from (select c1,
            (select sum(c2)
               from mycte
               where mycte.c1 = mycorr.c1 and mycte.c2 = 1) as
  mysum
              from mytable mycorr )
      where mysum > 0;
  

Local fix

• The incorrect results can be avoided by using the following
  registry setting via db2set or an Optimization
  profile/guideline:
  DB2COMPOPT=NO_GBPRDPU
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * ALL                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Db2 11.1 Mod 4 Fixpack 5 or higher                *
  ****************************************************************
  

Problem conclusion

• First fixed in Db2 11.1 Mod 4 Fixpack 5
  

Temporary fix

Comments

APAR Information

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

  IT29977

• 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