IT00386: SQL QUERY CONTAINS NOT EXISTS SUBQUERY AND NODENUMBER PREDICATE MIGHT PRODUCE AN INCORRECT RESULT

DB2 Version 10.1 Fix Pack 4 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 6 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• Under rare scenarios, DB2 might produce incorrect results if
  the following conditions are true:
  1) The query consists of one or more NOT EXISTS or NOT IN
  subqueries
  2) The parent side table of the subquery contains a nodenumber
  predicate
  
  eg.  select count(*)
          from t1
          where not exists (select 1 from t2 where t1.a=t2.a) and
  <-------------- condition 1
                       nodenumber(t1.a)=1;
  <-------------- condition 2
  

Local fix

• 1) Turn DB2_ANTIJOIN=NO
  2) Manually rewrite the query to form:
  select count(*) from t1 left join t2 on t1.a=t2.a where t2.a is
  null and nodenumber(t1.a)=1;
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to DB2 version 101 fixpack 4                         *
  ****************************************************************
  

Problem conclusion

• Problem is fixed in DB2 version 101 fixpack 4
  

Temporary fix

Comments

APAR Information

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

  IT00270

• 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

• RA10 PSY

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