Redo Log Buffer
The redo log buffer holds the most recent changes to the data blocks in the datafiles. When the
redo log buffer is one-third full, or every three seconds, Oracle writes redo log records to the redo
log files. As of Oracle Database 10g, the LGWR process will write the redo log records to the redo
log files when 1MB of redo is stored in the redo log buffer. The entries in the redo log buffer, once
written to the redo log files, are critical to database recovery if the instance crashes before the
changed data blocks are written from the buffer cache to the datafiles. A user??™s committed
transaction is not considered complete until the redo log entries have been successfully written
to the redo log files.
Large Pool
The large pool is an optional area of the SGA. It is used for transactions that interact with more
than one database, message buffers for processes performing parallel queries, and RMAN parallel
backup and restore operations. As the name implies, the large pool makes available large blocks
of memory for operations that need to allocate large blocks of memory at a time.
The initialization parameter LARGE_POOL_SIZE controls the size of the large pool and is a
dynamic parameter as of Oracle9i release 2.
Java Pool
The Java pool is used by the Oracle JVM (Java Virtual Machine) for all Java code and data within
a user session. Storing Java code and data in the Java pool is analogous to SQL and PL/SQL code
cached in the shared pool.
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