After connecting to your Oracle database through R console and run the command ore.sync, you may have faced with:

error. If you trace queries running while the sync command is in progress, you will see the one below:

Sequence rq$object_seq belongs to RQSYS schema and actually select is granted for this sequence to RQROLE database role. Even you granted RQROLE to the user you are trying to use R with, this sequence is not accessible to the user. So the workaround is quite simple, create synonym for the sequence, a public synonym if you intend to grant RQROLE to more than one user:

CREATE PUBLIC SYNONYM RQ$OBJECT_SEQ FOR RQSYS.RQ$OBJECT_SEQ;