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Datafile Contents (63)

原创 IT综合 作者:tsinglee 时间:2007-10-16 16:58:56 0 删除 编辑
When a datafile is first created, the allocated disk space is formatted but does not
contain any user data. However, Oracle reserves the space to hold the data for future
segments of the associated tablespace—it is used exclusively by Oracle. As the data
grows in a tablespace, Oracle uses the free space in the associated datafiles to allocate
extents for the segment.
The data associated with schema objects in a tablespace is physically stored in one or
more of the datafiles that constitute the tablespace. Note that a schema object does not
correspond to a specific datafile; rather, a datafile is a repository for the data of any
schema object within a specific tablespace. Oracle allocates space for the data
associated with a schema object in one or more datafiles of a tablespace. Therefore, a
schema object can span one or more datafiles. Unless table striping is used (where
data is spread across more than one disk), the database administrator and end users
cannot control which datafile stores a schema object.[@more@]

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