2.4.2 DB area types
DB areas can be classified according to application. The following table shows the available types of DB areas.
|
No. |
DB area type |
Description |
|---|---|---|
|
1 |
Data DB area |
This DB area stores tables and indexes. |
|
2 |
Work table DB area |
This DB area stores the work tables created by HADB while executing SQL commands. For details about work tables, see Types of work tables under Considerations when executing an SQL statement that creates work tables in Designs Related to Improvement of Application Program Performance in the HADB Application Development Guide. |
|
3 |
Master directory DB area |
This DB area stores the internal information for the entire system. |
|
4 |
Dictionary DB area |
This DB area stores dictionary tables (base tables) and B-tree indexes of dictionary tables (base tables). |
|
5 |
System-table DB area |
This DB area stores system tables (base tables) and B-tree indexes of system tables (base tables). |
- Note
-
All DB areas, except for the data DB area, are created automatically by HADB.
- ■ Dictionary table
-
Dictionary tables store definition information for base tables, viewed tables, B-tree indexes, text indexes, and range indexes, as well as DB area information.
Dictionary tables can be classified into base tables and viewed tables. For details, see B.1 Dictionary table overview.
- ■ System table
-
System tables store cost information related to base tables, B-tree indexes, and text indexes, as well as the chunk information for multi-chunk tables.
System tables can be classified into base tables and viewed tables. For details, see C.1 System table overview.