IT20634: INCORRECT RESSULT WHEN AT LEAST 3 COLUMNAR TABLES ARE JOINED THROUGH CDE NLJNS AND TOP NLJN IS EARLY OUT

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

APAR status

• Closed as program error.

Error description

• - If at least 3 COLUMNAR TABLES ARE JOINED THROUGH CDE NLJNS AND
  TOP NLJN IS EARLY OUT, then it is possible to get wrong plan
  where a predicate is evaluated too late in the plan, above early
  out join. In this case we could loose rows.
  
  - An example of a query that might generate a wrong plan:
  SELECT DISTINCT C1 FROM T1, T2, T3 WHERE (T1.C1 <> T2.C1) AND
  (T3.C2 <= T2.C2) AND (T1.C3 <= T3.C3)
  

Local fix

• Setting the following undocumented join support registry
  variable will solve the issue:
  db2set -im DB2_CDE_ILLEGAL_JOIN_SUPPORT=1
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Columnar tables only                                         *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Please, See Error Description and install this fix.          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Please, See Error Description and install this fix.          *
  ****************************************************************
  

Problem conclusion

• Please, See Error Description and install this fix.
  

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

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels

• RB10 PSY

     UP