The shared
pool is also used for caching information from the Oracle data dictionary, which is
the metadata that describes the structure and content of the database itself.
Youcan specify a SHARED_POOL_SIZE initialization parameter, or it will be automatically
sized if MEMORY_TARGET or SGA_TARGET is specified. Note that
prior to Oracle Database 10g, ???out of memory??? errors were possible if the shared
pool was undersized, but current Oracle database releases now can leverage automatic
shared memory tuning.
Redo log buffer
The redo log buffer caches redo information until it is written to the physical redo
log files stored on a disk. This buffer also improves performance. Oracle caches the
redo until it can be written to a disk at a more optimal time, which avoids the overhead
of constantly writing the redo logs to disk.
Other pools in the SGA
The SGA includes several other pools:
Large pool
Provides memory allocation for various I/O server processes, backup, and recovery,
and provides session memory where shared servers and Oracle XA for transaction
processing are used.
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