How to export base and discover its structure
You can generate an SQL file (of metadata) with built-in commandline tools (available on all database installations).

Just log in to the database server, create a full=y, content=metadata_only export:

expdp \'/ as sysdba\' full=y content=metadata_only


Then use impdp to generate an SQL file:

impdp \'/ as sysdba\' sqlfile=metadata.sql


Without specifying a location, Data Pump places its files by default in the directory DATA_PUMP_DIR, but expdp will display the full path of the file it created.