The Database Library is built on a Data Dictionary, which provides a complete description of record layouts and indexes of the database, for validation and efficient data access. You can use the data dictionary for automated database creation, including building tables, indexes, and referential constraints, and granting access rights to individual users and groups. The database dictionary supports the concept of Attached Objects, which allow database records to include compressed BLOBs (Binary Large Objects) containing images, text, sounds, video, documents, spreadsheets, or programmer-defined data types.
You can request information about the dictionary table
SELECT comments FROM dictionary WHERE table_name='DICTIONARY' COMMENTS -------------------------------------------------------------------------------- Description of data dictionary tables and views
DBA_VIEWS
Description of dba_views
· OWNER Owner of the view · VIEW_NAME Name of the view · TEXT_LENGTH Length of the view text · TEXT View text · TYPE_TEXT_LENGTH Length of the type clause of the object view · TYPE_TEXT Type clause of the object view · OID_TEXT_LENGTH Length of the WITH OBJECT OID clause of the object view · OID_TEXT WITH OBJECT OID clause of the object view · VIEW_TYPE_OWNER Owner of the type of the view if the view is an object view · VIEW_TYPE Type of the view if the view is an object view · SUPERVIEW_NAME Name of the superif view is a subview
To get Full list of your Data Dictionary view run following query on your database.
SELECT * from dba_views where owner = 'SYS' and view_name like 'DBA%'; ORDER BY view_name desc
[N.B: You can use TEXT field to view he information about the objects]
ALL_VIEWS
Description of all_views
· OWNER Owner of the view · VIEW_NAME Name of the view · TEXT_LENGTH Length of the view text · TEXT View text · TYPE_TEXT_LENGTH Length of the type clause of the object view · TYPE_TEXT Type clause of the object view · OID_TEXT_LENGTH Length of the WITH OBJECT OID clause of the object view · OID_TEXT WITH OBJECT OID clause of the object view · VIEW_TYPE_OWNER Owner of the type of the view if the view is an object view · VIEW_TYPE Type of the view if the view is an object view · SUPERVIEW_NAME Name of the superif view is a subview
You can also get Full list of your Data Dictionary view run following query.
select TEXT from ALL_VIEWS where owner='SYSTEM'
V$FIXED_TABLE
This Dynamic performance view Contains the name of all V$, X$ and GV$ tables.
Description of V$FIXED_TABLE
· NAME Name of the object · OBJECT_ID Identifier of the fixed object · TYPE Object type (TABLE | VIEW) · TABLE_NUM Number that identifies the dynamic performance table if it is of type TABLE
To get Full list of Dynamic Performance View (V$) run following query
SELECT name from V$FIXED_TABLE where name like 'V$%';
When using these views you should have timed_statistics set to true in your init.ora file. This has minimal effect on performance and can be permanently left on (TIMED_STATISTICS=TRUE)
GV$ views are dynamic performance views in a parallel server environment. There is a GV$ view for almost every V$ view. These have an additional column INST_ID (instance number)
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