Solution : https://service.sap.com/sap/support/notes/591387 (SAP Service marketplace login required)
Key words : 
invalid sample size specifiedbr886e checking/collecting statistics failed, terms updates statistics reason, sample size, ora-01493 sql errors, location stats_tab_collect-3ora-01493, table/index sapr3, br301e sql error -1493, 20 patch 29to download, update statistics, program error
Related Notes : 
       
| 514205 | Corrections in BR*Tools version 6.20 | 
| 403706 | Corrections in BR*Tools Version 6.10 |