Undo Segment An undo segment is used to save the old value (undo data) when a process changes data in a database. It stores the location of the data and the data as it existed before being modified. The header of an undo segment contains a transaction table where information about the current transactions using [...]
Archive for the ‘Tablespaces’ Category
3 Apr
Automatic segment space management
Automatic Segment-Space Management • Bitmap segments contain a bitmap that describes the status of each block in the segment with respect to its available space. • The map is contained in a separate set of blocks referred to as bitmapped blocks (BMBs). • When inserting a new row, the server searches the map for a [...]
3 Apr
Tablespaces
Tablespaces The data in an Oracle database are stored in tablespaces. • An Oracle database can be logically grouped into smaller logical areas of space known as tablespaces. • A tablespace can belong to only one database at a time. • Each tablespace consists of one or more operating system files, which are called data [...]
