Solution : https://service.sap.com/sap/support/notes/626172 (SAP Service marketplace login required)
Key words : 
prerequisites additional internal optimizer settings, symptom considerable performance problems, business information warehouse, unfavorable access plan, setting _push_join_predicate = true, hash_join_enabled=falseis set, terms outer join, outer join queries, current oracle release, _push_join_predicate = falsethe problem
Related Notes : 
       
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| 706132 | Composite SAP Note: Problems with Oracle 9i | 
| 621349 | |
| 619188 | FAQ: Oracle wait events | 
| 124361 | Oracle parameterization (R/3 >= 4.x, Oracle 8.x/9.x) |