Oracle Database 2 Day DBA 11g Release- P8

Oracle Database 2 Day DBA 11g Release- P8:Oracle Database 2 Day DBA is a database administration quick start guide that teachesyou how to perform day-to-day database administrative tasks. The goal of this guideis to help you understand the concepts behind Oracle Database. It teaches you how toperform all common administrative tasks needed to keep the database operational,including how to perform basic troubleshooting and performance monitoringactivities.
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Oracle Database 2 Day DBA 11g Release- P8 Managing Tables After partitions are defined, certain operations become more efficient. For example, for some queries, the database can generate query results by accessing only a subset of partitions, rather than the entire table. This technique (called partition pruning) can provide order-of-magnitude gains in improved performance. In addition, data management operations can take place at the partition level, rather than on the entire table. This results in reduced times for operations such as data loads; index creation and rebuilding; and backup and recovery. Each partition can be stored in its own tablespace, independent of other partitions. Because different tablespaces can be on different disks, this provides a table structure that can be better tuned for availability and performance. Storing partitions in different tablespaces on separate disks can also optimize available storage usage, because frequently accessed data can be placed on high-performance disks, and infrequently retrieved data can be placed on less expensive storage. Partitioning is useful for many types of applications that manage large volumes of data. Online transaction processing (OLTP) systems often benefit from improvements in manageability and availability, while data warehousing systems benefit from increased performance and manageability. Compressed Tables Table Compression is suitable for both OLTP applications and data warehousing applications. Compressed tables require less disk storage and result in improved query performance due to reduced I/O and buffer cache requirements. Compression is transparent to applications and incurs minimal overhead during bulk loading or regular DML operations such as INSERT, UPDATE or DELETE. You can configure table compression on the Storage subpage of the Create Table page. See Also: ■ Oracle Database Administrators Guide for design and management considerations for different table types ■ Oracle Database Concepts and Oracle Database VLDB and Partitioning Guide for more information about partitioned tables and indexes ■ Oracle Database Concepts for more information about LOBs, SecureFiles and BasicFiles ■ Example: Creating a Table on page 8-9Viewing Tables You can use Database Control to list all the tables in a specified schema, and to view the definitions of individual tables. To view tables: 1. Go to the Database Home page, logging in as user SYSTEM. See Accessing the Database Home Page on page 3-4. 2. At the top of the page, click Schema to view the Schema subpage. 3. In the Database Objects section, click Tables. The Tables page appears. 4. In the Schema field, enter the name of a schema. Alternatively, click the flashlight icon adjacent to the Schema field to search for a schema. Examples of schema names include SYS and hr. Managing Schema Objects 8-7Managing Tables 5. Leave the Object Name field blank to search for and display all tables in the schema. Alternatively, enter a table name or partial table name to limit the search. If you enter a search string in the Object Name field, all tables that have names that start with the search string are displayed. If you precede the search string with an asterisk (*), all tables that have the search string anywhere in the table name are displayed. 6. Click Go. The tables in the specified schema are displayed. 7. To view the definition of a particular table, select the table and then click View. Alternatively, click the table name. The View Table page appears. See Also: ■ About Tables on page 8-3Viewing Table Data Besides viewing table names and table definitions, you can view the data stored in the table, and the SQL statement used to display the data. You can also change the SQL statement to alter the results set. To view table data: 1. Search for a table as described in Viewing Tables on page 8-7. For example, search for the tables in the hr schema. 2. Select the table that contains the data that you want to view. For example, select employees. 3. In the Actions list, select View Data, and then click Go. The View Data for Table page appears.8-8 Oracle Database 2 Day DBA Managing Tables The Query field displays the SQL query that was run to view the data for the table. The Result section shows the data in the table. You may have to use the horizontal scroll bar at the bottom of the page to view all columns. 4. (Optional) Click a column name to sort the ...