• Oracle

    Oracle Indexes and Constraints-10

    Indexes: http://docs.oracle.com/cd/E11882_01/server.112/e40540/indexiot.htm#CNCPT1895 http://www.oracle.com/us/education/my-richardfoote-seminar-079059.html A table dependent object. (Root — Branch –Leaf) An index is an optional structure, associated with a table or table cluster. Index properties: Usability Indexes are usable (default) or unusable. An unusable index is not maintained by DML operations and is ignored by the optimizer. An unusable index can improve the performance of bulk loads. Instead of dropping an index and later re-creating it, you can make the index unusable and then rebuild it. Unusable indexes and index partitions do not consume space. When you make a usable index unusable, the database drops its index segment. When we move the table without index it will be unusable.…