Common Views and Their Uses


In your life as a DBA, many of the data dictionary views will become some of your most useful tools. They can tell you, at a glance, what is going on in your database, and who is doing what. You will likely (and you really should) create a library of useful and much-used and relied-upon scripts to provide information out of the data dictionary. This way, you can easily get the information that you need, and you don't have to think and rethink, check and recheck the contents of the views that you are accessing to get the information you are after.

Table 5.2 provides many of the most commonly used data dictionary views, their purpose, and their meanings. In a simple, generic database, with no additional products installed, there are more than 1,200 entries in the DICTIONARY view, so an exhaustive list should be generated on your own to familiarize yourself with the kinds of information that you can glean from the data dictionary. Although Table 5.2 lists the DBA views because this exam is geared to database administrators, there are usually equivalent USER or ALL views accessible by anyone logging in to the database.

Table 5.2. DICTIONARY View Entries

Purpose

View

Description

Provide general overview

DICTIONARY

Provides descriptions of data dictionary tables and views

 

DICT_COLUMNS

Provides descriptions of columns in the data dictionary tables and views

Provide information relevant about user objects, such as tables, constraints, columns, and indexes

DBA_TABLES

Provides information on tables in the database

 

DBA_OBJECTS

Provides information on stored objects in the database such as the owner, the object name and type, and often most relevant, its status (VALID or INVALID)

 

DBA_LOBS

Provides description of all LOBs contained in all tables

 

DBA_INDEXES

Provides description of all indexes in the database

 

DBA_TAB_COLUMNS Also DBA_TAB_COLS

Provides information on columns of user tables, views, and clusters

 

DBA_CONSTRAINTS

Provides information on all constraints in the database

Provide information about users, privileges, and roles

DBA_USERS

Provides information about all users in the database

 

DBA_SYS_PRIVS

Provides information on all system privileges that have been granted to either users or to roles in the database

 

DBA_ROLES

Provides information about all roles in the database

Space allocation for database objects

DBA_EXTENTS

Provides information concerning extents

 

DBA_SEGMENTS

Provides information concerning segments

 

DBA_FREE_SPACE

Provides information concerning free space

Provide information about database structures

DBA_ROLLBACK_SEGS

Provides description of all rollback segments

 

DBA_DATA_FILES

Provides information about all database data files

 

DBA_TABLESPACES

Provides a description of all tablespaces

Provide auditing information in the database

DBA_AUDIT_EXISTS

Provides a list of audit trail entries that have been produced by AUDIT EXISTS or AUDIT NOT EXISTS

 

DBA_AUDIT_OBJECTS

Provides audit trail records for statements that concern objects such as tables, clusters, views, indexes, sequences, public database links, synonyms, and so on

Provide information about currently running processes

V$ views

Provides information about the current state of connections, sessions, SQL, and other active information in the database


This is by no means an exhaustive list, and you should acquaint yourself with its components. The data dictionary is one of your most powerful tools as a DBA.



    Oracle 9i Fundamentals I Exam Cram 2
    Oracle 9i Fundamentals I Exam Cram 2
    ISBN: 0789732653
    EAN: 2147483647
    Year: 2004
    Pages: 244
    Authors: April Wells

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