Oracle自动内存管理的几个小问题(二)
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sys@HUA>
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sys@HUA>alter system set sga_target=0;
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System altered.
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sys@HUA>show parameter pool;
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NAME TYPE VALUE
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------------------------------------ ----------- ------------------------------
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_shared_io_pool_size big integer 0
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buffer_pool_keep string
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buffer_pool_recycle string
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global_context_pool_size string
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java_pool_size big integer 4M
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large_pool_size big integer 8M
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olap_page_pool_size big integer 0
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shared_pool_reserved_size big integer 7549747
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shared_pool_size big integer 208M
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streams_pool_size big integer 0
3) 是否有在SGA内的
组件，但是却不在自动内存管理之内的？
The following pools are manually sized components and are not affected by Automatic Shared Memory Management: * Log buffer * Other buffer caches (such as KEEP, RECYCLE, and other nondefault block size) * Fixed SGA and other internal allocations To manually size these memory pools, you must set the DB_KEEP_CACHE_SIZE, DB_RECYCLE_CACHE_SIZE, DB_nK_CACHE_SIZE, and LOG_BUFFER initialization parameters. The memory allocated to these pools is deducted from the total available for SGA_TARGET when Automatic Shared Memory Management computes the values of the automatically tuned memory pools.
4） 组件之间“挪借”内存空间，是按什么单位进行？是一个一个字节来分配？
Memory for the shared pool, large pool, java pool, and buffer cache is allocated in units of granules. The granule size is 4MB if the SGA size is less than 1GB. If the SGA size is greater than 1GB, the granule size changes to 16MB. The granule size is calculated and fixed when the instance starts up. The size does not change during the lifetime of the instance.
The granule size that is currently being used for SGA can be viewed in the view V$SGA_DYNAMIC_COMPONENTS. The same granule size is used for all dynamic components in the SGA.
5） 如果使用了自动内存管理，每个pool的值都设置为0了，那如何查看当前每个pool的当前值？
V$MEMORY_DYNAMIC_COMPONENTS displays information about the current sizes of all dynamically tuned memory components, including the total sizes of the SGA and instance PGA.