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Automatically Managed SGA Components (75)

原创 IT综合 作者:tsinglee 时间:2007-10-23 10:55:05 0 删除 编辑

When you set a value for SGA_TARGET, Oracle Database 10g automatically sizes the
most commonly configured components, including:
■ The shared pool (for SQL and PL/SQL execution)
■ The Java pool (for Java execution state)
■ The large pool (for large allocations such as RMAN backup buffers)
■ The buffer cache
■ The Streams pool
You need not set the size of any of these components explicitly. By default the
parameters for these components will appear to have values of zero. Whenever a
component needs memory, it can request that it be transferred from another
component by way of the internal automatic tuning mechanism. This transfer of
memory occurs transparently, without user intervention.
The performance of each of these automatically sized components is monitored by the
Oracle Database instance. The instance uses internal views and statistics to determine
how to distribute memory optimally among the components. As the workload
changes, memory is redistributed to ensure optimal performance. To calculate the
optimal distribution of memory, the database uses an algorithm that takes into
consideration both long-term and short-term trends.

当设置了SGA_TARGET后 ,Oracle 10g 自动调增大多数组件 , 如 :
共享池 ,java池 , 大池 ,高速缓存 , Streams pool


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