Types of Segments Segments are space-occupying objects in a database. They use space in the data files of a database. This section describes the different types of segments. Table A table is the most common means of storing data within a database. A table segment stores that data for a table that is neither clustered nor partitioned. Data within a table segment is stored in no particular order, and the database administrator (DBA) has very little control over the location of rows within the blocks in a table. All the data in a table segment must be stored in one tablespace. Table partition Scalability and. | Storage Structure and Relationships Objectives After completing this lesson, you should be able to do the following: Describe the logical structure of the database List the segment types and their uses List the keywords that control block space usage Obtain storage structure information Storage and Relationship Structure Database PROD DISK1/ DISK2/ DISK3/ DISK1/ DISK1/ . Table Data Seg . Index Index Seg RB Seg S_DEPT Data Seg S_EMP Data Seg Temp Temp Seg 1 2 1 2 1 2 1 1 2 2 1 FREE 1 1 2 2 1 EXTENTS S_DEPT (cont'd) Data Seg S_EMP FIRST_NAME Index Index Seg Oracle DATA BLOCKS RBS1 (cont'd) RB Seg RBS2 (cont'd) RB Seg RBS1 RB Seg RBS2 RB Seg SEGMENTS SYSTEM USER_DATA RBS TEMP TABLESPACES DATA FILES Types of Segments Table Cluster Table partition Index Types of Segments Segments are space-occupying objects in a database. They use space in the data files of a database. This section describes the different types of segments. . | Storage Structure and Relationships Objectives After completing this lesson, you should be able to do the following: Describe the logical structure of the database List the segment types and their uses List the keywords that control block space usage Obtain storage structure information Storage and Relationship Structure Database PROD DISK1/ DISK2/ DISK3/ DISK1/ DISK1/ . Table Data Seg . Index Index Seg RB Seg S_DEPT Data Seg S_EMP Data Seg Temp Temp Seg 1 2 1 2 1 2 1 1 2 2 1 FREE 1 1 2 2 1 EXTENTS S_DEPT (cont'd) Data Seg S_EMP FIRST_NAME Index Index Seg Oracle DATA BLOCKS RBS1 (cont'd) RB Seg RBS2 (cont'd) RB Seg RBS1 RB Seg RBS2 RB Seg SEGMENTS SYSTEM USER_DATA RBS TEMP TABLESPACES DATA FILES Types of Segments Table Cluster Table partition Index Types of Segments Segments are space-occupying objects in a database. They use space in the data files of a database. This section describes the different types of segments. Table A table is the most common means of storing data within a database. A table segment stores that data for a table that is neither clustered nor partitioned. Data within a table segment is stored in no particular order, and the database administrator (DBA) has very little control over the location of rows within the blocks in a table. All the data in a table segment must be stored in one tablespace. Table partition Scalability and availability are major concerns when there is a table in a database with high concurrent usage. In such cases, data within a table may be stored in several partitions, each of which resides in a different tablespace. The Oracle server currently supports partitioning by a range of key values, by a hashing algorithm, and by a list of values. If a table is partitioned, each partition is a segment, and the storage parameters can be specified to control them independently. Use of this type of segment requires the partitioning option within the Oracle9i .
