Tablespace
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Atablespaceis a storage location where the actual data underlyingdatabaseobjects can be kept. It provides a layer of abstraction between physical and logical data,[1]and serves to allocate storage for allDBMSmanaged segments. (A database segment is adatabase objectwhich occupies physical space such astabledata andindexes.) Once created, a tablespace can be referred to by name when creating database segments.
Overview
[edit]Tablespaces specify only the database storage locations, not the logical database structure, ordatabase schema.For instance, different objects in the same schema may have different underlying tablespaces. Similarly, a tablespace may service segments for more than one schema. Sometimes it can be used to specify schema so as to form a bond between logical and physical data.
By using tablespaces, an administrator also can control the disk layout of an installation. A common use of tablespaces is to optimize performance. For example, a heavily used index can be placed on a fastSSD.On the other hand, a database table which contains archived data that is rarely accessed could be stored on a less expensive but slowermagnetic hard drive.
While it is common for tablespaces to store their data in a filesystem file, a single file must be part of a single tablespace. Somedatabase management systemsallow tablespaces to be configured directly over operating-system device entries, calledraw devices,providing better performance by avoiding the OS filesystem overheads.
Oraclestores data logically in tablespaces and physically in datafiles associated with the corresponding tablespace.
References
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Oppel, Andrew J. (2009).Databases: a beginner's guide.McGraw Hill Professional. p. 44.ISBN978-0-07-160846-6.Retrieved2011-05-23.
[...] a logical file that forms a layer of abstraction between the physical and logical layers, thereby providing better logical data independence.