Describe Oracle9i architecture.

What will be an ideal response?

Oracle architecture contains three major areas: System Global Area (SGA) or memory structure, background processes and physical storage structure. The System Global Area (SGA) memory area is used for instance to store information that is shared by database and user processes. The SGA consists of a database buffer cache, a shared pool, Java pool and redo log buffers. In Oracle8i, Java pool was used only if Java was used, but it is required in Oracle9i. The database buffer cache contains actual data from the database. The user transactions are first stored in the buffer and then written to the disk. The shared pool contains the executed SQL and PL/SQL statements for reuse of the information. The shared pool keeps parsed statements based upon ‘least recently used’ algorithm.The redo log buffers store the redo entries for the online redo logs before writing

them to the disk.



The background processes run simultaneously and independently of each other. These

processes work on databases, and there can be a number of suc