Solution : https://service.sap.com/sap/support/notes/184275 (SAP Service marketplace login required)
Key words :
symptom transaction db02 shows missing primary indexes, view r3<sid>data/syskeycst, library r3<sid>data, r3<sid>data/<table>, additional key words addpfcst, r3<sid>data, unknown db indexes, change primary indexes, changing primary indexes, defective primary indexes