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使用数据库字典和动态性能视图 Copyright © Oracle Corporation, 2001. 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 5-2 Copyright © Oracle Corporation, 2001. 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 5-3 Copyright © Oracle Corporation, 2001. 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 Data files Control Redo files Log files Database Data Dictionary tables 5-4 Copyright © Oracle Corporation, 2001. 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 5-5 Copyright © Oracle Corporation, 2001. All rights reserved. Creating Data Dictionary Views 5-6 Script Purpose catalog.sql Creates commonly used data dictionary views and synonyms catproc.sql Runs scripts required for server-side PL/SQL Copyright © Oracle Corporation, 2001. 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 5-7 Copyright © Oracle Corporation, 2001. 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. 5-8 Copyright © Oracle Corporation, 2001. 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 DBA_xxx All of the objects in the database ALL_xxx Objects accessible by the current user USER_xxx Objects owned by the current user 5-9 Copyright © Oracle Corporation, 2001. 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 5-11 Copyright © Oracle Corporation, 2001. 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$FIXED_TABLE 5-12 Copyright © Oracle Corporation, 2001. All rights reserved. Dynamic Performance Table Examples • • • • • • • • • • • 5-13 V$CONTROLFILE V$DATABASE V$DATAFILE V$INSTANCE V$PARAMETER V$SESSION V$SGA $SPPARAMETER V$TABLESPACE V$THREAD V$VERSION Copyright © Oracle Corporation, 2001. All rights reserved. Administrative Scripts Naming Conventions 5-15 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 Copyright © Oracle Corporation, 2001. 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 5-16 Copyright © Oracle Corporation, 2001. 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 5-17 Copyright © Oracle Corporation, 2001. All rights reserved.