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 two 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（同義詞）
-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 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 all 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 |