Expert Indexing in Oracle Database 11g: Maximum Performance for Your Database

Understanding the Advantages

There are specific advantages of IOTs, including the following:

• Storage space can be saved because the data is the index, so there is only one segment or set of segments in the database for an index-organized table, rather than the normal two segments that come with a heap-organized table and associated index(es).
• Query performance benefits can occur because there are less I/O requirements. Since the data is stored as part of the index, there is a potentially significant I/O reduction.
• DML performance benefits can occur because there is only the need to update the index segment(s), as there is no data segment(s) as part of the structure. There is no need to update the table and then any associated index as with heap-organized ...