ORA-00600: internal error code, arguments: [kkestGetIdxKey: no key for idx!],
[], [], [], [], [], [], []

SELECT       mu_id, inv_id, stgr_id, heat_id 
     FROM material_unit 
     WHERE mu_id in 
         (SELECT      mu_id FROM 
             (SELECT   
                 mu.mu_id, mu.inv_id,
                 mu.stgr_id, mu.heat_id 
                 FROM
                 material_unit mu,
                 plant_configuration_item pci,
                 production_resource pr,
                 oper_res ors,
                 route_operation ro    WHERE mu.inv_id    = pci.inv_id
                 AND pci.pcfg_id    = 22
                 AND pci.res_id    = pr.res_id
                 AND ors.agres_id = pr.agres_id
                 AND ors.oper_id = ro.oper_id
                 AND ro.route_id = 'R1'
                 AND ro.step_number = 1
             )  )  
         AND      0.010000  < (SELECT to_number(chr_value) FROM material_unit_characteristic WHERE mu_id='SL18' AND mu_set = 1
                 AND chr_id = 'AVWGHT')