To understand how the optimizer ends up with 0.0014% as the filter factor, first look at the six elements in the IN list predicate.

为了了解优化器如何最终以 0.0014％ 作为过滤因子，首先要查看在 IN 清单谓词上的 6 个元素。

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Another way to use conditions is to apply a filter to a list of repeatable elements.

使用条件的另一方法是将筛选器应用到可重复元素的列表上，如第2部分中的“筛选数组”中所述。

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Two particularly useful procedural list functions are filter and map . The filter function takes a list and removes those elements that fail to meet some specified criterion.

两个非常有用的过程列表函数是filter和map 。

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