a2zinterviews

56.	What is a cluster key?
	The related columns of the tables are called the cluster key. The cluster key is indexed using a cluster index and its value is stored only once for multiple tables in the cluster.

57.	What is SGA?
	The System Global Area in an Oracle database is the area in memory to facilitate the transfer of information between users. It holds the most recently requested structural information between users. It holds the most recently requested structural information about the database. The structure is database buffers, dictionary cache, redo log buffer and shared pool area.

58.	What is a data segment?
	Data segment are the physical areas within a database block in which the data associated with tables and clusters are stored.

59.	What is ROWID?
	ROWID is a pseudo column attached to each row of a table. It is 18 characters long, blockno, row number are the components of ROWID.

60.	What is the usage of SAVEPOINTS?
	SAVEPOINTS are used to subdivide a transaction into smaller parts. It enables rolling back part of a transaction. Maximum of five save points are allowed.