les05_数据字典和性能视图.pptVIP

Using Data Dictionaryand Dynamic Performance Views Objectives After completing this lesson, you should be able to do the following: Identify built-in database objects Identify the contents and uses of the data dictionary Describe how data dictionary views are created Identify data dictionary view categories Query the data dictionary and dynamic performance views Describe administrative script naming conventions Built-In Database Objects Other objects created with the database: Data dictionary Performance tables PL/SQL packages Database event triggers 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 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 Creating Data Dictionary Views 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 a 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 all the schemas ALL: What the user can access USER: What is in the user’s schema 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_TABL