Property | Description |
---|---|
Parameter type |
Big integer |
Syntax |
|
Default value |
|
Modifiable |
|
Range of values |
64 MB 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 nonzero 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.
In the Default value field, IMMEDIATE
mode autotuning requests are necessary to avoid ORA-04031
errors. The DEFERRED
and IMMEDIATE
modes are reflected in the OPER_MODE
column of the V$MEMORY_RESIZE_OPS
view.
If Automatic Memory Management is enabled (MEMORY_TARGET
is set to a positive value) and SGA_TARGET
is also set to a positive value, the SGA_TARGET
value acts as the minimum value for the size of the SGA.
See Also:
Oracle Database Administrator's Guide for information on automatic memory management
Oracle Database Administrator's Guide for information on managing the SGA manually