IT37421: Wrong result for aggregate query via index - MIN for example - when NULL contained in column alongside non-NULL data

APAR status

• Closed as program error.

Error description

• When a select min ( column ) is used and the table contains a
  NULL value in the result set, the query returns different
  results depending on using a sequential scan or a index scan
  
  select  --+ index ( t1 )
  nvl(min(b),'isnull') from t1 where a in (2,3);
  select  --+ full ( t1 )
  nvl(min(b),'isnull') from t1 where a in (2,3);
  
  (expression)
  isnull
  1 row(s) retrieved.
  
  (expression)
  2
  1 row(s) retrieved.
  
  This problem started appearing in 12.10.xC14 and 14.10.xC4.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Users of Informix Server 12.10.xC14 and 14.10.xC4 - xC6.     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Informix Server 12.10.xC15 or 14.10.xC7 (when     *
  * available).                                                  *
  ****************************************************************
  

Problem conclusion

• Fixed in Informix Server 12.10.xC15 and 14.10.xC7.
  

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:

Fix information

• Fixed component name

  INFORMIX SERVER

• Fixed component ID

  5725A3900

Applicable component levels