DB2 FOR LUW / DB2FORLUW / B50 - DB2

If a query:
- contains a common subexpression ("CSE") over column-organized
tables
- SELECTs the same column from different references to that CSE
- orders the output on one copy of that column using ORDER BY

and the structure of the query is such that same column from the
different CSE references can have different values by the time
the data streams from those references join together, the output
might be ordered on the wrong copy of the column - the one from
the other CSE reference - rather than the specified one.

Example:

CREATE TABLE "FOJ "."TABLE6" (
"CD_DEMO_SK" INTEGER NOT NULL )
DISTRIBUTE BY HASH("CD_DEMO_SK")
IN "USERSPACE1"
ORGANIZE BY COLUMN;
ALTER TABLE "FOJ "."TABLE6" ADD PRIMARY KEY ("CD_DEMO_SK") NOT
ENFORCED;

CREATE TABLE "FOJ "."TABLE10" (
"C_CUSTOMER_SK" INTEGER NOT NULL ,
"C_BIRTH_DAY" INTEGER ,
"C_BIRTH_MONTH" INTEGER ,
"C_BIRTH_YEAR" INTEGER )
DISTRIBUTE BY HASH("C_CUSTOMER_SK")
IN "USERSPACE1"
ORGANIZE BY COLUMN;

ALTER TABLE "FOJ "."TABLE10" ADD PRIMARY KEY ("C_CUSTOMER_SK")
NOT ENFORCED;
insert into "FOJ "."TABLE6" values 1,2,3,4;
insert into "FOJ "."TABLE10" values
(1,1,1,1),(1,2,3,4),(2,3,4,5) ;

with v(c1, c2, c3) as
(select C_BIRTH_DAY, C_BIRTH_YEAR, count(C_BIRTH_MONTH) from
FOJ.TABLE10 group by C_BIRTH_DAY, C_BIRTH_YEAR)
select v1.c1 as w, v1.c2+v1.c3 as x, v2.c1, v2.c2+v2.c3 as z
from v v2 right join v v1 on v1.c2=v2.c3
order by v2.c1, x

W           X           C1          Z
----------- ----------- ----------- -----------
          1           2           3           6
          1           2           2           5
          1           2           1           2
          2           5           -           -
          3           6           -           -

  5 record(s) selected.

The rows should be in the order of C1.

****************************************************************
* USERS AFFECTED:                                              *
* All                                                          *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* See Error Description                                        *
****************************************************************
* RECOMMENDATION:                                              *
* Upgrade to 11.5.6 or later                                   *
****************************************************************

****************************************************************
* USERS AFFECTED:                                              *
* All                                                          *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* See Error Description                                        *
****************************************************************
* RECOMMENDATION:                                              *
* Upgrade to 11.5.6 or later                                   *
****************************************************************

Upgrade to 11.5.6 or later

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

25.01.2021
26.01.2021
23.06.2021