Oracle安装配置和使用概要.ppt

Oracle Database 10g: 2 Day DBA for Windows 1-* Managing Indexes Indexes are optional structures that are associated with tables. They can be created to increase the performance of data retrieval. An Oracle index provides a direct access path to table data. Indexes can be created on one or more columns of a table. After an index is created, it is automatically maintained and used by the Oracle server. When a table is updated, changes to the relevant indexes are automatically made with complete transparency to the user. You can click the Indexes link under the Schema heading of the Administration page to view the Indexes page. You can view index attributes or use the Actions menu to View Dependencies for an index. Indexes can be created explicitly, or they can be created implicitly by using constraints that are placed on a table. Oracle Database 10g: 2 Day DBA for Windows 1-* Creating and Dropping Indexes To create a standard (B-tree) index on one column: 1. Click table in the Schema region of the Administration page. The Tables page appears. 2. Enter the table name or use the search facility to select the table. Select Create Index from the Actions drop-down menu. Click Go. 3. The Create Index page appears. Enter a name for the new index. Enter the tablespace name and select Standard B-tree as the index type. 4. Select the column in the list of table columns by entering 1 in the Order column. Accept ASC as the Sorting Order. Click OK to create the index. 5. After the index is created, the Indexes page appears with a confirmation message. The new index is listed under Results. Perform the following steps to drop an index: 1. Select Indexes in the Schema region of the Administration page. The Indexes page appears. 2. Enter the index name or use the search facility to locate the index. Click Delete. 3. If you are certain you have identified the correct index, click Yes on the Confirmation page. 4. A confirmation message appears if the index has been successfull