Virtuoso supports multiple namespaces for tables and procedures.
A table or procedure is uniquely identified by a three part name
consisting of qualifier, owner and name separated by dots.
Each connection has a current qualifier which is used as the
default qualifier for if a name does not specify a qualifier. The
owner can be omitted from a name if the qualifier and name uniquely
identify the object, e.g. DB..SYS_KEYS.
Initially, all system objects have the qualifier DB and owner
The default current qualifier of all connections is DB unless
otherwise specified using db.dba.user_set_qualifier.
A user can be assigned a default qualifier set as current
qualifier upon login. This is done with the stored procedure
user_set_qualifier (in user varchar, in qualifier varchar)