oracle: sga_target

SGA_TARGET

Property	Description
Parameter type	Big integer
Syntax	SGA_TARGET = integer [K | M | G]
Default value	0 (SGA autotuning is disabled)
Modifiable	ALTER SYSTEM
Range of values	64 to operating system-dependent
Basic	Yes

SGA_TARGET specifies the total size of all SGA components. If SGA_TARGET is specified, then the following memory pools are automatically sized:

• Buffer cache (DB_CACHE_SIZE)
  
• Shared pool (SHARED_POOL_SIZE)
  
• Large pool (LARGE_POOL_SIZE)
  
• Java pool (JAVA_POOL_SIZE)
  
• Streams pool (STREAMS_POOL_SIZE)
  

If these automatically tuned memory pools are set to non-zero values, then those values are used as minimum levels by Automatic Shared Memory Management. You would set minimum values if an application component needs a minimum amount of memory to function properly.
The following pools are manually sized components and are not affected by Automatic Shared Memory Management:

• Log buffer
  
• Other buffer caches, such as KEEP, RECYCLE, and other block sizes
  
• Fixed SGA and other internal allocations
  

The memory allocated to these pools is deducted from the total available for SGA_TARGET when Automatic Shared Memory Management computes the values of the automatically tuned memory pools.