MongoDB如何索引数组？ [英] How does MongoDB index arrays?

问题描述

在MongoDB中，如果我要在字段color中存储一个数组（比如 [red，blue] ） ，是否索引red和blue所以我可以查询<例如，code>red，或者make {red，blue} 复合索引？

In MongoDB, if I were to store an array (say ["red", "blue"]) in a field "color", does it index "red" and "blue" so I could query for "red", for example, or does in make {"red", "blue"} a composite index?

推荐答案

当涉及到索引数组时，MongoDB会索引数组的每个值，以便您可以查询单个项目，例如red 。例如：

When it comes to indexing arrays, MongoDB indexes each value of the array so you can query for individual items, such as "red." For example:

> db.col1.save({'colors': ['red','blue']})
> db.col1.ensureIndex({'colors':1})

> db.col1.find({'colors': 'red'})
{ "_id" : ObjectId("4ccc78f97cf9bdc2a2e54ee9"), "colors" : [ "red", "blue" ] }
> db.col1.find({'colors': 'blue'})
{ "_id" : ObjectId("4ccc78f97cf9bdc2a2e54ee9"), "colors" : [ "red", "blue" ] }

有关更多信息，请查看MongoDB关于Multikeys的文档：http://www.mongodb.org/display/DOCS/Multikeys

For more information, check out MongoDB's documentation on Multikeys: http://www.mongodb.org/display/DOCS/Multikeys

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