what is SGA?

The System Global Area (SGA) is a group of shared memory areas that are dedicated to an Oracle “instance” (an instance is your database programs and RAM).




All Oracle processes use the SGA to hold information. The SGA is used to store incoming data (the data buffers as defined by the db_cache_size parameter), and internal control information that is needed by the database. You control the amount of memory to be allocated to the SGA by setting some of the Oracle “initialization parameters”.  These might include db_cache_size, shared_pool_size and log_buffer