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V2EX  ›  MySQL

MySQL 手册中的 dive into 该怎么理解?

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  •   virus94 · 309 天前 · 967 次点击
    这是一个创建于 309 天前的主题,其中的信息可能已经有所发展或是发生改变。

    在看 mysql5.7 的手册,看到 Optimization 章节时,发现这一段

     • Otherwise, any index on col_name is nonunique and the optimizer can estimate the row count for each
    range using dives into the index or index statistics.
    
    With index dives, the optimizer makes a dive at each end of a range and uses the number of rows in the
    range as the estimate. For example, the expression col_name IN (10, 20, 30) has three equality
    ranges and the optimizer makes two dives per range to generate a row estimate. Each pair of dives yields
    an estimate of the number of rows that have the given value.
    
      Index dives provide accurate row estimates, but as the number of comparison values in the expression
    increases, the optimizer takes longer to generate a row estimate. Use of index statistics is less accurate
    than index dives but permits faster row estimation for large value lists.
    

    查了一下有道词典,dive 翻译为潜水,俯冲,知乎上有个 DBA 翻译了这个章节,也翻译成潜水,总感觉不对.

    请教各位,这里面的 dive 和 dive into 该如何理解?

    3 回复  |  直到 2019-03-24 16:54:06 +08:00
        1
    mywaiting   309 天前   ♥ 1
    dive into 理解为“深入”?
        2
    fkdog   309 天前
    不止 dive into,还有 dig into,
        3
    isrfr   233 天前 via Android
    植入?
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