19. A system comprising: one or more processors; one or more non-transitory computer-readable media storing instructions, which, when executed by the one or more processors cause the system to perform operations comprising: a database server establishing a plurality of database sessions for access to a plurality of pluggable databases in a container database, wherein said container database includes a separate database dictionary for each pluggable database of said plurality of pluggable databases, wherein said database server establishing a plurality of database sessions includes, for each database session of said plurality of database sessions: receiving a connection request; determining that the connection request is for access to a particular pluggable database of said plurality of said pluggable databases; and attaching the respective database dictionary of said particular pluggable database to said each database session.
24. The system of claim 19 , wherein at least two pluggable databases of said plurality of pluggable databases each define a tablespace having a same tablespace name.