A D3 hashed table is a binary host table of a size equal to the modulo times the frame size, internally divided into groups. Modulo is the number of frames in the primary space of a hashed table.
A hashed table is composed of several host tables with the following reserved table extensions:
| Extension | Description |
|---|---|
| mds.D3S | The MDS table. There is normally only one MDS table per domain. |
| database.D3M | Master dictionary of a database can be located on any system on the network. The master dictionary is the root of the database table structure. By convention, the location of the master dictionary on the network is the location of the database, even though the tables in the database can be on another server. |
| tablename.D3D | The actual body or Primary table space of the hashed table for the dictionary level. |
| tablename.D3T | The actual body or Primary table space of the hashed table data level. |
| tablename.D3C | Table Control Block (TCB)—There is one table control block associated to each of the tables with the extensions D3S, D3M, and D3T and it is located on the same directory. |
| tablename.D3O | An optional overflow table. This table is only created on demand. It is located in the same directory as the table it extends (one of the tables with the extensions D3S, D3M, and D3T). |
| tablenameNNN.D3X | An optional index table. This table is only created on demand. It is located in the same directory as the table. NNN is an index number that uniquely identifies the index. |