Database Reference
In-Depth Information
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Streams pool
: This is a pool of memory used by data-sharing tools such as Oracle GoldenGate,
Oracle Streams, and so on. This pool is available in Oracle 10
g
and above and is resizable
online. If the Streams pool is not configured and you use the Streams functionality, Oracle will
use up to 10 percent of the shared pool for streams memory.
•
The “Null”
pool
: This one doesn't really have a name. It is the memory dedicated to block
buffers (cached database blocks), the redo log buffer, and a “fixed SGA” area.
A typical SGA might look as shown in Figure
4-1
.
Figure 4-1.
Typical SGA
The parameters that have the greatest effect on the overall size of the SGA are as follows:
JAVA_POOL_SIZE
: Controls the size of the Java pool.
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SHARED_POOL_SIZE
: Controls the size of the shared pool (to some degree).
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LARGE_POOL_SIZE
: Controls the size of the large pool.
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STREAMS_POOL_SIZE
: Controls the size of the Streams pool.
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DB_*_CACHE_SIZE
: Eight of these
CACHE_SIZE
parameters control the sizes of the various buffer
caches available.
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LOG_BUFFER
: Controls the size of the redo buffer (to some degree).
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SGA_TARGET
: Used with automatic SGA memory management in Oracle 10
g
and above, can be
changed online.
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SGA_MAX_SIZE
: Used to control the size of the SGA.
•
MEMORY_TARGET
: Used with automatic memory management (both PGA and SGA automatic
memory management) in Oracle 11
g
and above.
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MEMORY_MAX_SIZE
: Used to control the maximum amount of memory Oracle should strive to
use over both the PGA and SGA sizes under automatic memory management in Oracle 11
g
and above. This is really just a target; the PGA may exceed the optimum size if the number of
users increases beyond some level or a session(s) allocates large untunable bits of memory as
demonstrated earlier.
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