Overview of Oracle SGA Regions Donald K. Burleson

Overview of the Oracle SGA Regions

When an Oracle database is started, the Oracle executable issues the malloc( ) command to create a region of RAM memory.  The SGA is commonly called the Oracle region because it is a region of RAM memory on the database server RAM heap.

The Oracle DBA controls the size of the SGA, and proper SGA management can have a huge impact on performance.  However, we must remember that the SGA is a static memory region, and the needs of the Oracle database are constantly changing.  Until Oracle, the SGA was not dynamic and could not be altered.  After Oracle became commonplace in 2002, the dynamic adjustment of the SGA was common, and there is also speculation that a future release of Oracle will reconfigure itself based on the needs of the database. 

However, until then, changing the SGA requires constant monitoring, and it is sometimes a good approach to develop a general setting for the SGA parameters based on the historical needs of the application.

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