DB2 FOR LUW / DB2FORLUW / A50 - DB2

It is possible to get wrong results when access plan contains 
index scan on the outer leg of the hash join and filtering is 
applied to the scan results. 
 
Example below will demonstrate the issue. 
SQL using "WITH RR" will return correct results. 
SQL without "WITH RR" will return incorrect results. 
 
select count(*) from (select rowid rid from test1 where 
tabschema = 'MYSCHEMA') a , (select rowid rid from test1 where 
tabname = 'TEST1') b where a.rid = b.rid 
 
1 
----------- 
38 
 
 1 record(s) selected. 
 
select count(*) from (select rowid rid from test1 where 
tabschema = 'MYSCHEMA') a , (select rowid rid from test1 where 
tabname = 'TEST1') b where a.rid = b.rid WITH RR 
 
1 
----------- 
20020 
1 record(s) selected. 
 
Access plans will look the same and will have index scan on the 
outer leg of the hash join. 
In the problem case we will not qualify all rows on the outer of 
hash join due to problems with how we apply filtering.

**************************************************************** 
* USERS AFFECTED:                                              * 
* Wrong results                                                * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to v10.5fp6 or latest fixpak or use workaround below * 
* db2set DB2_TCG_DEFAULT_OPTIONS="set disable_pushdown on".    * 
* restart the instance.                                        * 
****************************************************************

db2set DB2_TCG_DEFAULT_OPTIONS="set disable_pushdown on". 
restart the instance.

not known / see Local fix

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

10.06.2015
19.01.2016
09.05.2017