Database Reference
In-Depth Information
USERNAME AUTHENTI COM
------------------------------ -------- ---
ANONYMOUS PASSWORD YES
APEX_040200 PASSWORD YES
APEX_PUBLIC_USER PASSWORD YES
[...]
45 rows selected.
SQL>
The security model obviously had to change as well. You can read more about that subject later in this chapter in
section “Users and roles”.
The Pluggable Database
After you have created the initial Container Database it is time to consider your options on how to proceed. You will
have at least one PDB in your CDB: the seed database. Other Pluggable Databases could have been created as well,
but in most cases you may want to keep the CDB lean during creation.
PDBs can be created using ASM and OMF or on the file system. The remainder of the chapter will try to
accommodate both of these but sometimes it is necessary to focus on just one. From a manageability point of view
using ASM with OMF is the easiest way to administer a CDB with PDBs.
The seed PDB
Every Container Database comes with exactly one seed database, and that fact cannot be changed. The seed database
has a fixed container ID of 2, and is opened read only by default. Every user-PDB has started its life a clone of the seed
PDB, directly or indirectly. The seed contains the bare minimum Oracle deems necessary to get a PDB cloned and
started. For that reason the seed is lightweight and comes with only two tablespaces: SYSTEM and SYSAUX. It also has
its own TEMP tablespace.
The seed database should not be modified at all, every attempt to open it will result in” ORA-65017: seed
pluggable database may not be dropped or altered”. This has an interesting implication: if you were hoping that you
could modify the seed to match your organization's database standards, then this is bad news. However, you can
have your custom “seed” database from which you clone your user-PDBs as you will see in the section “Managing
Pluggable Databases”.
The User-Pluggable Database
A User PDB in this topic indicates a Pluggable Database that has been cloned from either another user-PDB or the
seed database, but is open for business. In other words, the user-PDB is the application object, and responsible
for user connections and storing application data. Whenever you read about a PDB in the sections that follow you
probably read about a user PDB even if it is not explicitly mentioned.
As you will see shortly, Pluggable Databases are very flexible and can easily be transported between Container
Databases.
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