SGA_Target

sga_target 10g官档描述如下：

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.