Physical and logical database structures

A database is a collection of physical operating system files. The files that make up a database are redo logfiles, datafiles, control files, and temporary files. A logical database structure consists of tablespaces.

A tablespace is a logical storage unit within Oracle Database 11g XE. It is considered logical because a tablespace is not visible in the filesystem. A tablespace is a collection of one or more datafiles. A datafile belongs to one and only one tablespace. There are three types of tablespace in Oracle Database 11g XE — permanent, temporary, and undo. All our tables, indexes, and stored subprograms reside in a permanent tablespace. A temporary tablespace is used to process temporary data such as storing intermediate sorting results. All information related to undo (roll back) is stored in the undo tablespace. Undo records are used to roll back transactions when a ROLLBACK statement is issued or during recovery of the database.

Datafiles...