Shared Pool _ use large pool

Using the large pool
Use large pool

Unlike the shared pool, the large pool does not have an LRU list. Oracle does not
Attempt to age objects out of the large pool.
Unlike the shared pool, the large pool does not contain the LRU list. Oracle will not try to put objects
Remove from large pool because it is not used for a long time.
You shoshould consider refreshing ing a large pool if your instance uses any of
Following:

If your instance uses any of the following, you should consider using the large pool:

■ Parallel query
Parallel query uses shared pool memory to cache parallel execution message
Buffers.
Parallel query:
Parallel query uses the Shared Pool memory to cache parallel execution messages
■ Recovery Manager
Recovery Manager uses the Shared Pool to cache I/O buffers during Backup and
Restore operations. For I/O Server Processes and backup and restore operations,
Oracle allocates buffers that are a few hundred kilobytes in size.

Recovery Management
The recover Manager uses the Shared Pool to cache data in the I/O buffer during backup and recovery.
For I/O service processes and backup and recovery operations. Oracle will allocate buffers with a size of several hundred kb.
■ Shared Server
In a Shared Server architecture, the session memory for each client process is
Stored ded in the shared pool.

Shared Server:
In shared server access mode, the session memory of each client process is included in the shared pool.

Tuning the large pool and shared pool for the Shared Server Architecture
Debug large pool and share pool in Shared Server Mode

As Oracle allocates Shared Pool memory for Shared Server session memory,
Amount of Shared Pool memory available for the library cache and dictionary Cache
Decreases. If you allocate this session memory from a different pool, then oracle can
Use the Shared Pool primarily for caching shared SQL and not incur the performance
Overhead from shrinking the shared SQL cache.

Since Oracle allocates shared session memory from the share pool memory, there is not enough library Cache
And dictionary cache for the shared pool. If you allocate data to the session memory from different pools.
Therefore, Oracle can use the share pool to cache shared SQL, so as not to reduce the shared SQL cache.
Performance is affected.

Oracle recommends using the large pool to allocate the Shared Server-related user
Global Area (UGA), rather that using the Shared Pool.

Oracle recommends using the large pool to allocate UGA related to the Shared Server, rather than using the Shared Pool.

This is because Oracle uses the Shared Pool to allocate system global area (SGA) memory for other purposes,
Such as shared SQL and PL/SQL procedures. Using the large pool instead of the Shared Pool
Decreases fragmentation of the Shared Pool.

For other reasons, Oracle uses the Shared Pool to allocate SGA memory, such as shared SQL and PL/SQL stored procedures.
Using a large pool instead of a shared pool reduces the fragmentation of the Shared Pool.