I normally create my datafiles like this, with AUTOEXTEND ON and specifying a MAXSIZE:
ALTER TABLESPACE "INDX" ADD DATAFILE '/h01/oradata/MIMIDB/DATAFILES/indx12.dbf' SIZE 64M AUTOEXTEND ON NEXT 64M MAXSIZE 16384M;
My filesystem is nearing capacity and I cannot allow this datafile to continue to expand beyond whatever its current size happens to be (~8G). If I turn AUTOEXTEND OFF, does that mean I cannot add anything more to this datafile and I will receive an error if I try to do so? Do I need add another new mount point, /h02, to the filesystem and create an additional datafile for tablespace INDX there first, before turning AUTOEXTEND OFF on this datafile on /h01?