DB2 FOR LUW / DB2FORLUW / A10 - DB2

Queries in the following form may show bad performance when a 
CASE WHEN condition contains subqueries: 
 
SELECT COUNT(*) 
FROM 
   (SELECT T1.COL1, T1.COL2, T1.COL3, T1.COL4, 
           T1.COL5, T1.COL6, T1.COL7, T1.COL8 
   FROM TAB01 T1 INNER JOIN TAB02 T2 INNER JOIN session.#tt4 T3 
           ON 1=1 ON (T1.COL2 = T2.COL2) 
   WHERE ((T2.COL6 = 'My string' AS CHAR(16)FOR BIT DATA))) AND 
   CASE 
   WHEN (T3.COL55 > CAST(2 AS NUMERIC(1, 0))) 
   THEN CAST(x'01' AS CHAR(1) FOR BIT DATA) 
   ELSE 
      CASE 
      WHEN (((T2.MyCol_A IN (SELECT T4.MyCol_B AS MyCol_B FROM 
session.#tt5 T4)) 
          OR (T2.MyCol_C IN (SELECT T5.MyCol_B AS MyCol_B FROM 
session.#tt5 T5))) 
          OR (T2.MyCol_D IN (SELECT T6.MyCol_B AS MyCol_B FROM 
session.#tt5 T6))) 
      THEN CAST(x'01' AS CHAR(1) FOR BIT DATA) 
      ELSE CAST(x'00' AS CHAR(1) FOR BIT DATA) 
      END 
   END = CAST(x'01' AS CHAR(1) FOR BIT DATA))

**************************************************************** 
* USERS AFFECTED:                                              * 
* all                                                          * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to version 10.1 Fix Pack 5                           * 
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First fixed in version 10.1 Fix Pack 5

not known / see Local fix

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

19.03.2015
16.07.2015
16.07.2015