With an Index Organized Tables, a table is stored in an index structure. This imposes physical order on the rows themselves.
Whereas in a heap, the data is stuffed wherever it might fit, in an index organized table the data is stored in sorted order, according to the primary key. Efficient when most of the column values are included in the primary key. You access the index as if it were a table and the data is stored in a B-tree like structure.
An (IOT) index-organized table stores the entire contents of the table's row in a B-tree index structure. An IOT provides fast access for queries that have exact matches and/or range searches on the primary key. Even though an IOT is implemented as a B-tree index structure, it is created via the