ensure
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n. ??; ???? vt. ??...;
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MongoDB verifyIndex() ??? ???
??: MongoDB? verifyIndex() ???? ???? ???? ?????.
??: >db.COLLECTION_NAME.ensureIndex({KEY:1}) ???? Key ?? ????? ??? ??? ?? 1? ??? ???? ?????? ????? ?????. ?????? ???? ????? -1?? ????? ??????.
MongoDB verifyIndex() ??? ?
>db.col.ensureIndex({"title":1})
>
ensureIndex() 方法中你也可以設置使用多個字段創(chuàng)建索引（關系型數據庫中稱作復合索引）。
>db.col.ensureIndex({"title":1,"description":-1})
>