Automatically Managed SGA Components (75)

最新推荐文章于 2025-12-18 10:59:28 发布

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当设置SGA_TARGET参数后，Oracle10g能够自动调整共享池、Java池、大池、缓冲区高速缓存及Streams池等组件的大小，以适应当前的工作负载。这些组件的内存分配会根据长期和短期趋势进行优化调整。

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.