An index only scan is an index access that is not followed by a table access because the index itself contains all the requested data.

仅扫描索引是未包含表访问的索引访问，因为索引本身包含了所有被请求的数据。

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Typically, a non-matching index scan is chosen by the optimizer when the underlying index provides benefits such as index-only access, avoids sort, or some similar benefit.

通常情况下，在基础索引提供好处(如唯一索引访问、避免排序或一些类似的好处)时，可通过优化器选择非匹配索引扫描。

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The option can be used in non matching index scans in a screening fashion and as part of index-only access.

该选项以筛选的方式用于非匹配索引扫描，且是仅索引访问的一部分。

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