Solution : https://service.sap.com/sap/support/notes/852365 (SAP Service marketplace login required)
Key words : 
symptom inefficient sql statement, prerequisites inefficient sql statement, enter 'reference object id', cost base optimizer, consult sap note 724545, cost based   optimizer, missing database index, press ctrl-f32, field short text, start transaction se11
Related Notes : 
       
| 724545 | Adjusting the CBO statistics manually using DBMS_STATS |