Solution : https://service.sap.com/sap/support/notes/428212 (SAP Service marketplace login required)
Key words : 
bw control tables rsnspace/rspspace, bw control table rsnspace, cost-based optimizer reason, control tables rsnspace/rspspace, additional customer/partner namespaces, include additional table groups, strictly speaking infocube tables, control table dbstatc, abap report sap_analyze_all_infocubes, supplied package dbms_stats
Related Notes : 
       
| 1013912 | FAQ: Oracle BW performance | 
| 588668 | FAQ: Database statistics | 
| 567745 | Composite note BW 3.x performance: DB-specific setting | 
| 524341 | Updating the statistics for individual partitions | 
| 424239 | New BRCONNECT parameter: stats_dbms_stats | 
| 408532 | Using the DBMS_STATS package for collecting statistics | 
| 403713 | BRCONNECT: Parallel updating of statistics | 
| 403704 | BRCONNECT - Enhanced function for Oracle DBA | 
| 129252 | Oracle DB Statistics for BW Tables |