文档介绍：Storage Structure and Relationships
Objectives
pleting 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
anized table
Index partition
Undo segment
Temporary segment
Types of Segments
LOB segment
Bootstrap segment
Nested table
Storage Clause Precedence
Oracle default
Tablespace
Segment
Extent Allocation and Deallocation
An extent is a chunk of space used by a segment within a tablespace.
An extent is allocated when the segment is:
Created
Extended
Altered
An extent is deallocated when the segment is:
Dropped
Altered
Truncated
Used and Free Extents
Data file
Free extent
Used extent
File header