DB2 FOR LUW / DB2FORLUW / A50 - DB2

Under rare conditions, a SQL statement involving equality joins 
between 4 or more column-organized tables, with a subset of at 
least 3 tables on the same join columns which are also connected 
through joins to one or more other tables on different join 
columns, might produce incorrect results.  This is best 
explained using an example, such as the following: 
 
select * from t1,t2,t3,t4 where t1.a=t2.a and t1.b=t4.b and 
t2.c=t4.c and t2.c=t3.c and t1.d=t3.d 
 
where t1,t2,t3, and t4 are column-organized tables.  The join 
between t2,t3, and t4 are on the same column, c.  The optimizer 
identifies this relationship and will consider all join orders 
involving these 3 tables.  Furthermore, t2,t3,and t4 are also 
connected through the join with t1, but on different columns. 
In this type of scenario, the optimizer will consider 
alternative join orders that might cause this error.

**************************************************************** 
* USERS AFFECTED:                                              * 
* DB2 UDB Version 10.5                                         * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to Version 10.5 FixPack 7.                           * 
****************************************************************

If you expect you are hitting this issue, you can apply an 
optimization guideline to request a different join order from 
the optimizer.

Problem was first fixed in DB2 UDB Version 10.5 FixPack 7.

not known / see Local fix

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

04.02.2015
20.01.2016
27.04.2016