Automatic Shared Memory Management (ASMM)
With manual configuration, it is possible
for compiled SQL
frequently age out of the shared pool due to inadequate size.
With automatic SGA management, the internal tuning algorithm
monitors the workload performance and increases the shared pool
as needed to reduce the number of parses.
The ASMM feature uses a new Memory Manager
(MMAN) background process. MMAN coordinates the sizing of the
memory components and acts as a memory broker. The MMAN keeps
track of all memory components and pending resize operations.
Based on workload information from AWR, the
ASMM can capture statistics periodically,
every 60 minutes for
example, in the background, use different memory
advisories, and move memory to where it is most needed
whether that be the
large pool or buffer cache. For example in a long running OLTP
day job, a larger buffer cache is needed; while for a data
warehousing (DSS) batch job at night, more memory is needed for
the large pool. The ASMM moves the memory to buffer cache or
large pool as needed.