Managing Oracle Multitenant Databases - OCP: Oracle Database 12c Administrator Certified Professional - page 578

the CDB. Set this parameter to the number of background processes, plus your estimate of
the maximum number of concurrent users, plus 10 percent for recursive sessions.
The default values of the TRANSACTIONS parameters are derived from SESSIONS . If you
increase the value of SESSIONS , you should also increase the value for TRANSACTIONS .
In a CDB, the root container's SESSIONS parameter specifies the total number of sessions
for the multitenant CDB and associated PDBs. The SESSIONS parameter for a PDB indicates
the maximum number of sessions that can utilize that PDB, and by default, it is the same
value as for the CDB root. If the maximum number of sessions is reached for a PDB, the
next attempt to connect will throw an ORA-00018 error.
The SESSIONS parameter for a PDB can't exceed the CDB SESSIONS value and can be
modified only by the PDB.
Summary
In this chapter, you learned more about the Oracle Database 12 c multitenant architecture,
how to manage a CDB and PDBs, how to establish connections to a CDB and PDBs, how
to shut down and start up a CDB, how to open and close PDBs, and how certain initializa-
tion parameters influence the CDB and PDBs.
To establish a connection to a CDB, you first learned about common users and local users
and then how to connect to the CDB and to PDBs using SQL*Plus. We showed you how to set
up a service for a PDB and connect using tnsnames.ora . We explained how to change the cur-
rent container from the CDB$ROOT to a PDB. You also created a common user and a local user.
After teaching you how to connect to the CDB and to PDBs, we showed you how to
start up and shut down container databases. You learned that the STARTUP and SHUTDOWN
commands for the CDB are basically the same as for a non-CDB. You saw that you can
open and close PDBs in addition to using the STARTUP and SHUTDOWN commands on PDBs.
Finally, you learned that several initialization parameters influence the CDB and PDBs.
Parameters related to the audit trail, maximum sessions, maximum column sizes, resource
plans, enabling pluggable databases, filename conversion for PDB provisioning, and non-
CDB compatibility settings were discussed.
Exam Essentials
Know how to establish connections to the different database container types in the Oracle
Database 12 c multitenant architecture. Make sure you understand how to connect to a
CDB and a PDB. Know the different methods for each.
Know how to create a connection to a PDB. Know that you must create a valid service
and a method to resolve the service name, for example, by using tnsnames.ora .