The main purpose of the Oracle data dictionary is to store data that describes the structure of the objects in the Oracle database. Because of this purpose, there are many views in the Oracle data dictionary that provide information about the attributes and composition of the data structures within the database.
All of the views listed in this section actually have three varieties, which are identi-fied by their prefixes:
DBA_
Includes all the objects in the database. A user must have DBA privileges to use this view.
USER_
Includes only the objects in the user’s own database schema.
Data Dictionary Tables | 121 ALL_
Includes all the objects in the database to which a particular user has access. If a user has been granted rights to objects in another user’s schema, these objects will appear in this view.
This means that, for instance, there are three views that relate to tables: DBA_
TABLES, USER_TABLES, and ALL_TABLES.
Some of the more common views that directly relate to the data structures are described in Table 4-2.
Table 4-2. Data dictionary views about data structures
Data dictionary view Type of information
ALL_TABLES Information about the object and relational tables TABLES Information about the relational tables TAB_COMMENTS Comments about the table structures TAB_HISTOGRAMS Statistics about the use of tables
TAB_PARTITIONS Information about the partitions in a partitioned table
TAB_PRIVS* Different views detailing all the privileges on a table, the privileges granted by the user, and the privileges granted to the user
TAB_COLUMNS Information about the columns in tables and views COL_COMMENTS Comments about individual columns
COL_PRIVS* Different views detailing all the privileges on a column, the privileges granted by the user, and the privileges granted to the user
LOBS Information about large object (LOB) datatype columns
VIEWS Information about views
INDEXES Information about the indexes on tables IND_COLUMNS Information about the columns in each index IND_PARTITIONS Information about each partition in a partitioned index
PART_* Different views detailing the composition and usage patterns for partitioned tables and indexes CONS_COLUMNS Information about the columns in each constraint
CONSTRAINTS Information about constraints on tables SEQUENCES Information about sequence objects SYNONYMS Information about synonyms
TAB_COL_STATISTICS Statistics used by the cost-based analyzer TRIGGERS Information about the triggers on tables TRIGGER_COLS Information about the columns in triggers
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CHAPTER 5
Managing Oracle
5Many Oracle users and developers are not actively aware of the system and database management activities that go on around them. But effective management is vital to providing a reliable, available, and secure platform that delivers optimal perfor-mance. This chapter focuses on how you can manage Oracle to ensure these virtues for your environment.
Much of the management responsibility usually falls upon the database administrator.
Users and developers of Oracle also need to be aware of some of the techniques described here. The DBA is typically responsible for the following management tasks:
• Installing and upgrading the database and options
• Creating tables and indexes
• Creating and managing tablespaces
• Managing control files, online redo logs, archived redo logs, job queues, and server processes
• Creating, monitoring, and tuning data-loading procedures
• Adding users and groups and implementing security procedures
• Implementing backup, recovery, information lifecycle management, and high availability plans
• Monitoring database performance and exceptions
• Reorganizing and tuning the database
• Troubleshooting database problems
• Coordinating with Oracle Worldwide Customer Support Services
Particularly in smaller companies, DBAs are also often called upon to take part in database schema design and security planning. DBAs in large enterprises may also help set up replication strategies, disaster and high-availability strategies, hierarchical storage management procedures, and the linking of database event monitoring (e.g., specific database tasks and status) into enterprise network monitors.
Managing Oracle | 123 Oracle’s feature list has grown with each database release. Yet managing Oracle can be much less labor-intensive today than it was in the past. While database releases highlighted in early editions of this book described the novelty of an easier-to-use man-agement interface, producing better versions of Oracle Enterprise Manager (EM) was only part of the effort to simplify management underway within Oracle Server Devel-opment. The database itself has now become more self-tuning and self-managing.
Initially, this effort was focused mostly on better management of single instances of the Oracle database. Oracle Database 10gexpanded its capabilities with a focus on grid computing. Grid computing highlighted the need for effective management of scores of computers and database instances.
Manageability of a grid must take into account disk virtualization, resource pooling, provisioning of computer resources, dynamic workload management, and dynamic control of changing grid components. Oracle’s grid initiative resulted in many signifi-cant changes in managing the database geared toward signifisignifi-cantly reducing this complexity. While targeted at simplifying grid management, most of these improve-ments also provide great impact in simplifying management of more traditional Oracle database implementations.
As a consequence of the grid initiative and tuning and self-managing initiatives, readers of early editions of this book will find a large number of management changes in this chapter and in others throughout this book.
All of the tasks we’ve just described come under the heading of managing the data-base. Many of the provisioning duties, including installation, initial configuration, and cloning, are discussed in Chapter 3. Security issues are discussed in Chapter 6.
This chapter explores the following aspects of managing Oracle:
• Using Oracle Enterprise Manager, which provides an easy-to-use interface and underlying framework for many database-management tasks, including new database capabilities
• Managing database fragmentation, which can affect database performance
• Performing backup and recovery operations and information lifecycle manage-ment, which are the foundation of database integrity protection
• Working with Oracle Support
In subsequent chapters, we’ll cover other related topics in more depth, including security, performance, and high availability. You will need an understanding of all of these areas as youplan and implement effective management strategies for your Ora-cle database environment.
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