List report shows double rows for some of the Items which belongs to the spesific level in a hierarchy. Report contains Union Query and grouping.
Extra rows were shown on month level Item - list showed multiple identical rows under month level grouping where other columns also had identical values.
Product issue. Stitching of queries failed to match records with 'NULL' values correctly and remove corresponding rows. Design change to product code was made for Cognos 10.2.1 (10.2 RP1) where stitch functionality was improved introducing "StitchWithNulls" -parameter (ref. APAR PM83742).
IBM Cognos 10.1.1 and 10.2.0
Diagnosing the problem
Happens using either Conventional Query Mode (CQM) or Dynamic Query Mode (DQM).
Resolving the problem
To enbale advanced parameter "StitchWithNulls", locate "CQEConfig.xml" file under "[Cognos Install]/configuration" directory on application server and add xml entry under the "QueryEngine" section:
<entry name="StitchWithNulls" value="1"/>