To get the datafile sizes from the database

col file_name for a70
col tablespace_name for a30
clear breaks
clear computes
compute sum of SIZE_IN_MB on report
break on report
select tablespace_name,file_name,AUTOEXTENSIBLE,INCREMENT_BY,MAXBYTES/1024/1024 “MAX in MB”,bytes/1024/1024 “SIZE_IN_MB” from dba_data_files order by tablespace_name;