Database Reference
In-Depth Information
Before we establish connections, let's discuss users and containers in the multitenant
environment.
Chapter 11, “Creating Oracle Multitenant Databases,” demonstrates how
to create CDBs and PDBs. The exercises in this chapter assume that you
have created a CDB and PDBs.
User Accounts in a CDB
In the multitenant environment, a user is either a common user, which has access to all con-
tainers in the CDB, or a local user, which has access only to the PDB in which it was created.
The Common Users in a CDB
In the context of a CDB, the word common is used to indicate that some entity is common to
all containers. In context, local means that an entity is restricted to exactly one container.
A common user is a CDB user that has the same identity in CDB$ROOT and in all PDBs and
can connect to and perform operations in the root and in any PDB where it has CREATE
SESSION privileges. Examples of common users that are created with each CDB are SYS and
SYSTEM . The ability to create, modify, or delete CDB-wide attributes of a common user or
role is restricted to a common user connected to the root. A common user with appropriate
privileges can switch between containers and administer PDBs from the root. A DBA-created
common user has the following characteristics:
Username begins with the characters c## or C## .
Username contains only ASCII or EBCDIC characters.
Resides in the root and uses the same identity to connect to every PDB.
The schema associated with a common user can be different in each PDB.
It is not essential for a common user to have the same privileges in every PDB. In
Exercise 12.1, we will demonstrate how to create a common user in an existing CDB.
The Local Users in a CDB
The local user is not a common user but is local to a specific PDB and can operate in only
a single PDB. A user who has the CREATE USER role or greater within a PDB, including
common users, can create a local user. A local user has the following characteristics:
Username may not begin with the characters c## or C## .
Is unique and specific to a particular PDB and owns a schema in the same PDB.
Can't be created in the root.
Can't log on to another PDB or to the root.
If granted, can access objects in a common-user schema in the same PDB.
In Exercise 12.2, we will demonstrate how to create a local user in an existing PDB.
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