About tablespace starting from Oracle8i, Oracle supports two types of tablespaces: Dictionary management method tablespace: The management information of all storage spaces in the tablespace is saved in the data dictionary. Local management method tablespace: All storage spaces in the tablespace are stored in the "bitmap" in the header of the data file.
1, Dictionary Management Table Space Create TableSpace ... DataFile '...' 'Size ... unuseExtent Management Dictionary
2, local management table space Create TableSpace ... DataFile '...' size ... unuseExtent management local autoallocate / unform size ... segment space management manual / auto.autoallocate is automatically managed by Oracle's assignment of the area. In the Autoallocate mode, the smallest area in the table space is 64kb.uniform size ... The maximum advantage of it is that no storage debris is generated in the table space to avoid waste of storage space.
.SEGMENT SPACE Management Manual (default) Oracle will use the available list (Free List) to manage the free data blocks in the segment. .SEGMENT SPACE Management Autoracle uses a bitmap to manage the used data blocks and free data blocks in segments.
