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  • sqloraclesharePool 天高地厚

    发出一个sql语句或sql命令,让数据库执行,那么sql语句在数据库内部就要被解析,建立它的execution plan(执行规划(计划)),然后按照执行计划去执行。
    每一个sql语句都要被解析,解析成原子操作去执行。解析好的sql语句都会存在共享池里面。
    Shared Pool used to store:
    --Most recently executed SQL statements
    --Most recently used data definitions
    It consists of two key performance-related memory structures:
    --Library Cache
    --Data Dictionary Cache
    ======================
    How to resize the shared pool:
    alter system set shared_pool_size = 64M;

    ======================
    Library Cache:
    It stores information about the most recently used SQL and PL/SQL statements
    (存储的是经过编译解析后的SQL语句和PL/SQL语句)
    Enables the sharing of commonly used statements.
    Is managed by a Last Recently Used(LRU) algorithm.
    Consists of two structures:
    --Shared SQL area
    --Shared PL/SQL area
    Size determined by the Shared Pool Sizing
    ====================
    (如果现在执行的sql语句已经在LibraryCache中了,就不需要再解析,就可以提高执行速度)

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  • 原文地址:https://www.cnblogs.com/net2012/p/2874791.html
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