Oracle Large Pool is an optional memory component of the oracle database SGA. This area is used for providing large memory allocations in many situations that arise during the operations of an oracle database instance.

1. Session memory for the a shared server and the Oracle XA Interface when distributed transactions are involved

2. I/O Server Processes

3. Parallel Query Buffers

4. Oracle Backup and Restore Operations using RMAN

Large Pool plays an important role in Oracle Database Tuning since the allocation of the memory for the above components otherwise is done from the shared pool. Also due to the large memory requirements for I/O and Rman operations, the large pool is better able to satisfy the requirements instead of depending on the Shared Pool Area.

Usage of a Large Pool Area allows the shared pool to primarily cache SQL and avoid the overhead casued by shrinking the SQL Cache Area