Solution : https://service.sap.com/sap/support/notes/131372 (SAP Service marketplace login required)
Key words : 
note 766349, prerequisites
Related Notes : 
       
| 766349 | FAQ: Oracle SQL optimization | 
| 303462 | Required information for expensive SQL statements | 
| 215917 | Easy change from Rule to Cost-Based Optimizer | 
| 132861 | CBO: Statistics creation with SAPDBA or BRCONNECT | 
| 130480 | Database Hints in Open SQL for Oracle | 
| 129385 | Database hints in Open SQL | 
| 127715 | CBO: Optimum parameters for performance | 
| 125588 | Corrections in SAPDBA version 4.0B | 
| 124361 | Oracle parameterization (R/3 >= 4.x, Oracle 8.x/9.x) | 
| 122718 | CBO: Tables with special treatment | 
| 114716 | Performance problems Oracle 8.0.4/all entries | 
| 109034 | Collective note: SAPDBA - performance/CBO | 
| 106047 | DB21: Customizing the DBSTATC | 
| 96296 | CC-ERROR: Database problem in client copy | 
| 93256 | CBO: Changes for installation of 4.0 | 
| 93098 | CBO: Changes in upgrade to 4.0 | 
| 31511 | Program runs very long: Performance analysis | 
| 19466 | Downloading SAP kernel patches |