Overview
In 9i, Shared Pool and Default Buffer Cache SGA parameters are made Dynamic. Alter system command can be used to modify these parameters. The total size of SGA is limited by SGA_MAX_SIZE.
When the size of these parameters are adjusted using “alter system” freed memory need to be reallocated manually.
In 10g ASMM relieves DBA from manually sizing SGA.
When ASMM is enabled shared pool, large pool, java pool and DB Cache components of SGA are dynamically sized by Oracle.
Following Benefits can be achieved by ASMM
- Allocation of memory to the right component of SGA based on current activity
- Reducing the chance of memory errors
Configuration
ASMM can be enabled by setting SGA_TARGET initialization parameter. To disable it SGA_TARGET should be set to zero and following manual parameters should be configured.
- DB_KEEP_CACHE_SIZE,
- DB_RECYCLE_CACHE_SIZE,
- DB_nK_CACHE_SIZE,
- LOG_BUFFER,
- FIXED SGA and
- STREAMS_POOL_SIZE
Even when ASMM is enabled individual SGA components can be changed using alter system command.
Related Views:
v$sga_dynamic_components
Conclusion:
10g manages memory efficiently by adapting to current workload