v$db_cache_advice 字段解释

Question

因为建议器做预测是，DB_CACHE_SIZE 的预测值的增长步长是相同
的，是16M。我们按照这一步长增加DB_CACHE_SIZE，如果每次增加物理读降低都很明
显，就可以继续增加，直到物理读降低不明显，说明继续增加DB_CACHE_SIZE 没有太大作
用。当然，性能和可用资源是天平的两端，你需要根据自己系统的实际情况调整。

Answer 1

连接到:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining optionsSQL> select size_for_estimate, estd_physical_read_factor,
  2  estd_physical_reads
  3  from v$db_cache_advice
  4  where name = 'DEFAULT';SIZE_FOR_ESTIMATE ESTD_PHYSICAL_READ_FACTOR ESTD_PHYSICAL_READS
----------------- ------------------------- -------------------
                4                     1.163              140179
                8                    1.0312              124291
               12                    1.0185              122759
               16                    1.0097              121702
               20                    1.0049              121120
               24                         1              120529
               28                     .9941              119813
               32                     .9906              119397
               36                     .9886              119156
               40                     .9845              118656
               44                     .9803              118157SIZE_FOR_ESTIMATE ESTD_PHYSICAL_READ_FACTOR ESTD_PHYSICAL_READS
----------------- ------------------------- -------------------
               48                     .9677              116634已选择12行。
--两个网址备用
--http://www.oracle.com/technology/global/cn/pub/articles/oracle-database-11g-top-features/11g-caching-pooling.html--http://www.oracle.com/technology/global/cn/obe/obe10gdb_vmware/manage/saa/saa.htm