tailieunhanh - OCA: Oracle Database 11g Administrator Certified Associate- P15

Tham khảo tài liệu 'oca: oracle database 11g administrator certified associate- p15', công nghệ thông tin, cơ sở dữ liệu phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Managing Tablespaces 531 MANAGEMENT AUTO clause. Oracle strongly recommends AUTOMATIC segment space management for permanent locally managed tablespaces and the default behavior of Oracle 11g is AUTO. Here is a statement that creates a tablespace with manual segment space management CREATE TABLESPACE hr_index DATAFILE u02 oradata 11GR11 SIZE 2G EXTENT MANAGEMENT LOCAL AUTOALLOCATE SEGMENT SPACE MANAGEMENT MANUAL When automatic segment space management is specified bitmaps are used instead of free lists to identify which data blocks are available for inserts. The parameters PCTFREE and PCTUSED are ignored for segments in tablespaces with automatic segment space management. Automatic segment space management is available only on tablespaces configured for local extent management it is not available for temporary or system tablespaces. Automatic segment space management performs better and reduces your maintenance tasks making it the preferred technique. To specify automatic segment space management use the SEGMENT SPACE MANAGEMENT AUTO clause of the CREATE TABLESPACE statement like this or do not include the SEGMENT SPACE MANAGEMENT clause it is the default CREATE TABLESPACE hr_index DATAFILE u02 oradata 11GR11 SIZE 2G EXTENT MANAGEMENT LOCAL AUTOALLOCATE SEGMENT SPACE MANAGEMENT AUTO When automatic segment space management is used Oracle ignores the storage parameters PCTUSED FREELISTS and FREELIST GROUPS when creating objects. Although the name segment space management sounds similar to extent management it is quite different and can be more accurately regarded as block space management. Choosing Other Tablespace Options Several options are available to use when creating a tablespace. You learned to create BIGFILE or SMALLFILE tablespaces and use the EXTENT MANAGEMENT and SEGMENT SPACE MANAGEMENT options in the previous sections. In this section you will learn the other options available while creating a tablespace Specifying .