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 DBA.

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 db.dba.user_set_qualifier.

user_set_qualifier  (in user varchar, in qualifier varchar)