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  • 查看library_cache 库缓冲区的命中率


    关于library cache的命中率:
        SQL> desc V$librarycache
        NAMESPACE                                        VARCHAR2(64)
        GETS                                                NUMBER
        GETHITS                                             NUMBER
        GETHITRATIO                                        NUMBER
        PINS                                                 NUMBER
        PINHITS                                              NUMBER
        PINHITRATIO                                         NUMBER
        RELOADS                                             NUMBER
        INVALIDATIONS                                       NUMBER
        DLM_LOCK_REQUESTS                                 NUMBER
        DLM_PIN_REQUESTS                                   NUMBER
        DLM_PIN_RELEASES                                    NUMBER
        DLM_INVALIDATION_REQUESTS                        NUMBER
    DLM_INVALIDATIONS                                    NUMBER


    计算library cache的命中率:
        NAMESPACE=SQL AREA
        Library Cache Hit Ratio = sum(pinhits) / sum(pins)  以下语句计算librarycache 命中率



    库缓存区的命中率应保持在95%,否则应考虑增大shared_pool_size
     
    SYS @ prod >SELECT SUM(pins) "Executions",SUM(reloads) "CacheMisses while Executing", ROUND((SUM(pins)/(SUM(reloads)+SUM(pins)))*100,2)   "HitRatio, %" FROM V$LIBRARYCACHE;

    Executions       CacheMisses while Executing         HitRatio, %
    ---------- --------------------------- ------------------------ ------------------------ -----------
     131527               2472                         98.16

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  • 原文地址:https://www.cnblogs.com/iyoume2008/p/4690709.html
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