OCP 1Z0 052 128

128. Note the points about data dictionary views and dynamic performance views: 
1) These are stored in the SYSTEM tablespace. 
2) These are the based on the virtual tables. 
3) These are owned by the SYS user. 
4) These can be queried by a normal user only if O7_DICTIONARY_ACCESSIBILTY parameter is set to 
TRUE. 
5) The V$FIXED_TABLE view can be queried to list the names of these views. 
Which statements listed describe the data dictionary views? 
A.1 and 3 
B.2, 3, and 5 
C.1, 2, and 3 
D.2, 3, 4, and 5 
Answer: A

Storage of the Data Dictionary

The data dictionary base tables are the first objects created in any Oracle database. All data dictionary tables and views for a database are stored in the SYSTEM tablespace. Because the SYSTEM tablespaceis always online when the database is open, the data dictionary is always available when the database is open.

How Oracle Database Uses the Data Dictionary

The Oracle Database user SYS owns all base tables and user-accessible views of the data dictionary. Data in the base tables of the data dictionary is necessary for Oracle Database to function. Therefore, only Oracle Database should write or change data dictionary information. No Oracle Database user should ever alter rows or schema objects contained in the SYS schema because such activity can compromise data integrity. The security administrator must keep strict control of this central account.

Restricting System Privileges by Securing the Data Dictionary

To secure the data dictionary, set the O7_DICTIONARY_ACCESSIBILITY initialization parameter to FALSE, which is the default value. This feature is called the dictionary protection mechanism.

The O7_DICTIONARY_ACCESSIBILITY initialization parameter controls restrictions on system privileges when you upgrade from Oracle Database release 7 to Oracle8i and later releases. If the parameter is set to TRUE, then access to objects in the SYSschema is allowed (Oracle Database release 7 behavior). Because the ANY privilege applies to the data dictionary, a malicious user with ANY privilege could access or alter data dictionary tables.

The V$FIXED_TABLE view contains information about all of the dynamic performance tables and views.

SQL> SELECT COUNT(*)  2    FROM DICTIONARY;  COUNT(*)----------      26661 row selectedSQL> SELECT COUNT(*)  2    FROM dictionary  3   WHERE table_name NOT IN (SELECT NAME FROM v$fixed_table);  COUNT(*)----------      16221 row selected

SQL> col name form a10SQL> col REFERENCED_NAME form a20SQL> col owner form a10SQL> SELECT NAME, referenced_name, referenced_type, owner  2    FROM dba_dependencies  3   WHERE NAME = 'ALL_TABLES';NAME       REFERENCED_NAME      REFERENCED_TYPE    OWNER---------- -------------------- ------------------ ----------ALL_TABLES USER$                TABLE              SYSALL_TABLES SEG$                 TABLE              SYSALL_TABLES TAB$                 TABLE              SYSALL_TABLES TS$                  TABLE              SYSALL_TABLES ALL_TABLES           VIEW               PUBLICALL_TABLES DEFERRED_STG$        TABLE              SYSALL_TABLES OBJ$                 TABLE              SYSALL_TABLES OBJAUTH$             TABLE              SYSALL_TABLES X$KSPPI              TABLE              SYSALL_TABLES X$KSPPCV             TABLE              SYSALL_TABLES X$KZSRO              TABLE              SYSALL_TABLES V$ENABLEDPRIVS       VIEW               SYS12 rows selected

SQL> SELECT t.table_name, t.owner, t.tablespace_name  2    FROM dba_tables t  3   WHERE t.table_name = 'USER$';TABLE_NAME                     OWNER      TABLESPACE_NAME------------------------------ ---------- ------------------------------USER$                          SYS        SYSTEM1 row selected

SQL> SELECT t.table_name, t.owner, t.table_name  2    FROM dba_tables t  3   WHERE t.table_name = 'USER$';TABLE_NAME                     OWNER      TABLE_NAME------------------------------ ---------- ------------------------------USER$                          SYS        USER$1 row selected