Use
dictionary-managed tablespaces only for compatibility with previous
versions of Oracle.
When you use locally managed tablespaces, the data dictionary is not updated and rollback
activity is not generated during extent creations. Locally managed tablespaces automatically track
adjacent free space, so there is no need to coalesce extents. Within a locally managed tablespace,
all extents can have the same size or the system can automatically determine the size of extents.
To use local space management, you can specify the local option for the extent management
clause in the create tablespace command. An example of the create tablespace command
declaring a locally managed tablespace is shown here:
create tablespace CODES_TABLES
datafile '/u01/oracle/VLDB/codes_tables.dbf'
size 500M
extent management local uniform size 256K;
Assuming that the block size for the database in which this tablespace is created is 8KB, in
this example, the tablespace is created with the extent management declared as local and with
a uniform size of 256KB. Each bit in the bitmap describes 32 blocks (256/8). If the uniform size
clause is omitted, the default is autoallocate. The default size for uniform is 1MB.
NOTE
If you specify local in a create tablespace command, you cannot
specify a default storage clause, minextents, or temporary. If you use
the create temporary tablespace command to create the tablespace,
you can specify extent_management local.
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