IT35689: Query with 'ORDER BY' and referencing a common subexpression over column-organized tables may return rows in the wrong order

Db2 Version 11.1 Mod 4 Fix Pack 7 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• 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.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to db2_v111m4fp7 or later                            *
  ****************************************************************
  

Problem conclusion

• Upgrade to db2_v111m4fp7 or later
  

Temporary fix

Comments

APAR Information

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

  IT35685

• 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

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