Local management table space is greatly improved compared to dictionary management table spaces, which is as follows:
1. Reduce recursive space management
Local management table space is your own management allocation, not the icon dictionary management table space requires a system to manage space allocation, and local tablespace is to track the remaining in this file by maintaining a bitmap by maintaining a bitmap in each data file in table space. Space and usage, and timely update (in principle, a bitmap area is added to the head of the data file per table space, record the usage status of each area. Each table file is 64K In Bit Map. Whenever a zone is used, or is released for re-use, Oracle will update this record of the data file header to reflect this change). This update is only modified on the quota of the table space without any UPDATE operations for other data dictionary, so it does not generate any rollover information, which greatly reduces spatial management and improves management efficiency. At the same time, due to the local management table space, the unified size allocation method can be used, and spatial management is also greatly reduced, and the database performance is improved.
2. The system automatically manages the EXTENTS size or uses a unified extents size.
The local management table space has autoallocate and unified size assignment (uniform), autoallocate is automatically determined by the system to determine the extents size, and the unified size assignment (unified) is specified by the user Extents size. Both allocation improves spatial management efficiency.
3. Reduce the competition between data dictionary
Because local management tablespace tracks the space situation in this file by maintaining a bitmap of each data file and updating, this update only modifies the quota of the table space without involving other data dictionary tables, thus It greatly reduces the competition between data dictionary tables and improves database performance.
4. Do not generate a rollover information
Since space management of local management table space does not modify any other data dictionary in addition to the trial of the table space, no return information is generated, thereby greatly improves the running speed of the database.
5. Do not merge adjacent remaining space
Because the EXTENTS space management of the local management table space automatically tracks adjacent remaining spaces and automatically manages the system, there is no need to merge adjacent remaining spaces. At the same time, all of the EXTents in the local management table space can also have the same size, thereby reducing space fragments.
6. Reduce space fragments
7. Provide better management for temporary tablespace
