Connecting to a CDB or PDB

• Connecting to a CDB or PDB is not different of connecting to a standard database.
• When you create a PDB, it is automatically assigned a service which can be used to reach this specific PDB.
• You can either use the EZ connect syntax, the Oracle Net Service syntax or the new : ALTER SESSION SET CONTAINER syntax.
• The CDB_SERVICES view lets you view the services for each PDB.
• The SHOW CON_NAME command can be used to identify the container your are connected to.

Users and administrative tasks

• Only a common user can connect to CDB$ROOT.
• To use the ALTER SESSION SET CONTAINER command, a common user must have the SET CONTAINER privilege.
• All management tasks except PLUG/UNPLUG and STOP/START  in a PDB are equivalent to a standard database.
• You can use the CONTAINER=ALL clause in a DDL statement to execute it in all PDBs. This can only be done by a common user with the SET CONTAINER privilege.
• By DEFAULT when you issue a DDL the CONTAINER clause is equal to CURRENT.
• A common user name starts wth C##

Continue reading OCP 12C – Managing CDBs and PDBs →

The multitenant architecture

• Needs enterprise edition and the multitenant option.
• Consists of a CDB (Container database) and zero, one or up to 252 PDBs (pluggable databases).
• Has a root container (the CDB itself) and a seed container (template to create PDBs)
• There is only one instance per CDB.
• A PDB doesn’t have :
  • background processes
  • undo tablespace, it uses the CDB’s.
  • redologs, it uses the CDB’s.
  • controlfiles
• A PDB have :
  • It’s own tablespaces
  • It’s own local users and local roles
  • It’s own metadata
• A PDB CAN have :
  • a temporary tablespace or can use the CDB temporary tablespace.
  • it’s own Resource Manager Plan or can use the default CDB one.
• Users can be common users (at the CDB level) or local users (local to a PDB)

Continue reading OCP 12C – Basics of Multitenant Container Database (CDB) →

EM Database Express

• The old Enterprise Manager database control is replaced by Enterprise Manager database express in Oracle 12c.
• It contains only basic administration capabilities as the advanced ones are included in Enterprise Manager cloud control
• With EM database Express you can manage Security (Users, roles, profiles), Configuration (Instance Parameters, memory, database features), Storage (tablespaces, undo, redo, archive logs, control files), Performance.
• Enterprise Manager needs the XML DB component.
• You can configure the port used by EM database Express using :  exec DBMS_XDB_CONFIG.setHTTPsPort(5500);
• You can get the port configured for EM database Express using :  select DBMS_XDB_CONFIG.getHTTPsPort from dual;
• The EM_EXPRESS_BASIC (read-only role)  and EM_EXPRESS_ALL (access all functionnalities) roles can be used to grant access to EM Database Express to non-administrative users.
• You can’t start or stop your DB with EM database express, this means that you database is accessible through EM database express only when you opened it.
• Listener should be up and running for access to EM Express being possible.
• Alternative for performing some DBA admin tasks is the DBA tab of SQLDeveloper