Data dictionaries and dynamic performance views

Built-indatabase Objects

Other objects created with the database:

· Data Dictionary

· Performance tables

Pl/sql Packages

· Database event triggers

Data Dictionary

· Central Toevery Oracle Database

· Describes the database and it ' s objects

· Contains read-only tables and views

· Stored in the SYSTEM tablespace

· Owned by the user SYS

· Maintained by the Oracle server

· Accessed with SELECT

Base Tables & Data Dictionary views

The data dictionary contains and parts:

· Base tables

-stores Description of the database

-create with Create DATABASE

· Data Dictionary views

-used to simplify the base table information

-accessed through public synonyms (synonyms)

-create with the Catalog.sql script

Createdata Dictionary views

Script	Purpose
Catalog.sql	Creates commonly used data dictionary views and  synonyms
Catproc.sql	Runs scripts required for Server-side PL/SQL

Data Dictionary Contents

The data dictionary provides information about:

· Logical and physical database structures

· Definitions and space allocations of objects

· Integrity constraints

· Users

· Roles

· Privileges

· Auditing

How does the Data Dictionary is used?

Primary uses:

· Oracle Server uses it to find information about:

-users

-schema objects

-storage Structures

· Oracle server modifies it when a DDL statement is executed

· Users and DBAs use it as read-only reference for information about the database

Data Dictionary View Categories

· Three sets of static views

· Distinguished by their scope:

-dba:what is in the schemas

-all:what the user can access

-user:what is in the USER ' s schema

Data Dictionary Tables Examples:

· General Overview: dictionary, Dict_columns.

· Schema objects:dba_tables, Dba_indexes, Dba_tab_columns, dba_constraints.

· Space allocation:dba_segments, Dba_extents.

· Database structure:dba_tablespaces, Dba_data_files.

Dynamic perfomance Tables

· Virtual tables

· Record Current database activity

· Continually updated while the database is operational

· Information is accessed from memory and control file

· Used to monitor and tune the database

· owned by SYS user

· synonyms begin with v$

· Listed Inv$fixed_table

Dynamic Performanceexamples

V$controlfile

V$database

V$datafile

v$instance

V$parameter

v$session

V$SGA

V$spparameter

V$tablespace

V$thread

v$version

Admin Script naming

Convention	Description
Cat*.sql	Catalog and Data dictionary information
Dbms*.sql	Database Package Specifications
Prvt*.plb	Wrapped database Package Code
Utl*.sql	Views and tables for database Utilities

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Data dictionaries and dynamic performance views