Solution : https://service.sap.com/sap/support/notes/449477 (SAP Service marketplace login required)
Key words : 
terms business information warehouse, convert individual multiprovider queries, bw olap engine, abap report sap_rsadmin_maintain, system immediately passes, resulting partial queries, parallel processing reason, convert processing, partial queries, relevant queries
Related Notes : 
       
| 840080 | Errors or incorrect data with MultiProvider query | 
| 801313 | Questions about queries based on virtual InfoCubes | 
| 782537 | Financial statement queries and multiprovider | 
| 629541 | Multiprovider: Parallel Processing | 
| 622841 | OLAP: Parallel processing on query level can be deactivated | 
| 607164 | MultiProvider: Sequential processing is faster than parallel | 
| 567746 | Composite note BW 3.x performance: Query & Web applications | 
| 529022 | Wrong values with MultiProvider, parallel proc., E/F split | 
| 518030 | Multiservice provider query with node selection in structure | 
| 495523 | Incorrect Multicube and exception aggregation results | 
| 327876 | MultiCube query and using several aggregates |