5 Copyright © Oracle Corporation, All rights reserved. 使用数据库字典和动态性能视图

5-2 Copyright © Oracle Corporation, All rights reserved. 目标 学完这个课程，你应该可以掌握你下内容 : 区别内置的数据库对象 区别数据字典的内容和用法 理解数据字典视图是如何创建的 区别数据字典视图的种类 查询数据字典和动态性能视图 理解 administrative script 命名规则

5-3 Copyright © Oracle Corporation, All rights reserved. 内置的数据库对象 Other objects created with the database: Data Dictionary Performance tables PL/SQL packages Database event triggers

5-4 Copyright © Oracle Corporation, All rights reserved. Data Dictionary Central to every Oracle database Describes the database and its 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 Control files Data files Redo Log files Database Data Dictionary tables

5-5 Copyright © Oracle Corporation, All rights reserved. Base Tables and Data Dictionary Views The data dictionary contains two parts: Base tables –Stores description of the database –Created with CREATE DATABASE Data dictionary views –Used to simplify the base table information –Accessed through public synonyms –Created with the catalog.sql script

5-6 Copyright © Oracle Corporation, All rights reserved. Creating Data Dictionary Views ScriptPurpose catalog.sql Creates commonly used data dictionary views and synonyms catproc.sql Runs scripts required for server-side PL/SQL

5-7 Copyright © Oracle Corporation, All rights reserved. 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

5-8 Copyright © Oracle Corporation, All rights reserved. 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 a read-only reference for information about the database.

5-9 Copyright © Oracle Corporation, All rights reserved. Data Dictionary View Categories Three sets of static views Distinguished by their scope: – DBA : What is in all the schemas – ALL : What the user can access – USER : What is in the user’s schema USER_xxx Objects owned by the current user ALL_xxx Objects accessible by the current user DBA_xxx All of the objects in the database

5-10 Copyright © Oracle Corporation, All rights reserved.

5-11 Copyright © Oracle Corporation, All rights reserved. Data Dictionary 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

5-12 Copyright © Oracle Corporation, All rights reserved. Dynamic Performance 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 in V$FIXED_TABLE

5-13 Copyright © Oracle Corporation, All rights reserved. Dynamic Performance Table Examples V$CONTROLFILE V$DATABASE V$DATAFILE V$INSTANCE V$PARAMETER V$SESSION V$SGA $SPPARAMETER V$TABLESPACE V$THREAD V$VERSION

5-14 Copyright © Oracle Corporation, All rights reserved.

5-15 Copyright © Oracle Corporation, All rights reserved. Administrative Scripts Naming Conventions Convention cat*.sql dbms*.sql prvt*.plb utl*.sql Description Catalog and data dictionary information Database package specifications Wrapped database package code Views and tables for database utilities

5-16 Copyright © Oracle Corporation, All rights reserved. Summary In this lesson, you should have learned how to: Identify built-in database objects Identify the contents and uses of the data dictionary Understand how data dictionary views are created Identify data dictionary view categories Query the data dictionary and dynamic performance views Understand administrative script naming conventions

5-17 Copyright © Oracle Corporation, All rights reserved. Practice 5 Overview This practice covers the following topics: Identify the components and contents of the data dictionary Query the data dictionary

5-18 Copyright © Oracle Corporation, All rights reserved.

5-19 Copyright © Oracle Corporation, All rights reserved.

5-20 Copyright © Oracle Corporation, All rights reserved.