Comparison of local management table space and dictionary management table space

Comparison
The Local management table space greatly improves management efficiency and database performance compared to the Dictionary management table space, with the following advantages:

1. Reduced recursive space management

The Local management table space is the management of its own allocation, rather than the dictionary management table space requires a system to manage the allocation of space, the surface space is through the table space in each data file to maintain a bitmap to track the remaining space in this file and the use of the block. and make updates in time. This update only modifies the amount of tablespace and does not perform any update operations on other data dictionary tables, so no fallback information is generated, which greatly reduces space management and improves management efficiency. At the same time, because the local management table space can adopt the uniform size distribution (uniform), it also greatly reduces the space management and improves the database performance.

2. The system automatically manages the extents size or adopts the unified extents size

The Local management table space has automatic allocation (autoallocate) and uniform size allocation (uniform) two spatial allocation methods, automatic allocation (autoallocate) is the system to automatically determine the size of the extents, and uniform size allocation (uniform) The user specifies the extents size. Both of these methods improve the efficiency of space management.

3. Reduced competition between data dictionaries

Because the local management table space keeps track of the space and updates of blocks in this file by maintaining a bitmap of each data file, this update modifies only the amount of tablespace and does not involve other data dictionary tables, thus greatly reducing competition among data dictionary tables and improving database performance.

4. Do not generate fallback information

Because the spatial management of the local management table space does not modify any other data dictionary tables except for the amount of table space, it does not produce fallback information, thus greatly increasing the speed of the database.

5. No need to merge adjacent remaining space

Because the extents space management of the local management table space automatically tracks adjacent remaining space and is automatically managed by the system, there is no need to merge adjacent remaining space. At the same time, all extents of the local management table space can also have the same size, thereby reducing space fragmentation.

6. Reduction of space debris

7. Provides better management of temporary tablespace space