Jump to Navigation

195 - Oracle SGA Memory

The SGA is a chunk of memory that is allocated by an Oracle Instance (during the nomount stage) and is shared among Oracle processes,
hence the name. It contains all sorts of information about the instance and the database that is needed to operate.

Variable size:
This is combination of shared pool, Java pool and Large Pool

Fixed portion :
The size of the fixed portion is constant for a release and a plattform of Oracle, that is, it cannot be changed through any means
such as altering the initialization parameters.

Redo log buffer :
Redo Buffers is roughly equal to the parameter log_buffer.

Database buffers :
It's size is equal to db_block_size * db_block_buffers.

SQL> show sga;

Total System Global Area  612368384 bytes
Fixed Size                  1250428 bytes
Variable Size             171969412 bytes (shardpool+java pool + large pool)
Database Buffers          432013312 bytes
Redo Buffers                7135232 bytes


SQL> select sum(bytes) from v$sgastat where pool in ('shared pool', 'java pool', 'large pool');


Main menu 2

Story | by Dr. Radut