Data Dictionary stores metadata about structure of database - Database

Q.  What stores the metadata about the structure of the database, in particular the schema of the database?
- Published on 28 Aug 15

a. Indices
b. Database log
c. Data files
d. Data Dictionary

ANSWER: Data Dictionary
 

    Discussion

  • Nirja Shah   -Posted on 30 Oct 15
    - One of the most important parts of an Oracle database is its data dictionary, which is a read-only set of tables that provides information about the database.

    - A data dictionary contains:

    - The definitions of all schema objects in the database (tables, views, indexes, clusters, synonyms, sequences, procedures, functions, packages, triggers, and so on)

    - How much space has been allocated for, and is currently used by, the schema objects

    - Default values for columns

    - Integrity constraint information

    - The names of Oracle users

    - Privileges and roles each user has been granted

    - Auditing information, such as who has accessed or updated various schema objects

    - Other general database information

    - The data dictionary is structured in tables and views, just like other database data.

    - All the data dictionary tables and views for a given database are stored in that database's SYSTEM tablespace.

    - Not only is the data dictionary central to every Oracle database, it is an important tool for all users, from end users to application designers and database administrators.

    - Use SQL statements to access the data dictionary.

    - Because the data dictionary is read-only, you can issue only queries (SELECT statements) against it's tables and views.

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