如何为 mongodb 中的特定文档创建复合索引

Question

我是运行 MongoDB 4.2，请看下面我的文件长什么样：

{
    "_id" : ObjectId("61e8e5b72e74b7fc3e16b632"),
    "1" : 2,
    "age_upon_outcome" : "1 year",
    "animal_id" : "A725717",
    "animal_type" : "Cat",
    "breed" : "Domestic Shorthair Mix",
    "color" : "Silver Tabby",
    "date_of_birth" : "2015-05-02",
    "datetime" : "2016-05-06 10:49:00",
    "monthyear" : "2016-05-06T10:49:00",
    "name" : "",
    "outcome_subtype" : "SCRP",
    "outcome_type" : "Transfer",
    "sex_upon_outcome" : "Spayed Female",
    "location_lat" : 30.6525984560228,
    "location_long" : -97.7419963476444,
    "age_upon_outcome_in_weeks" : 52.9215277777778
}

最重要的是，我需要创建一个复合索引，以提高查找“outcome_type”为“Transfer”的品种的查询性能，但我不确定如何创建将下面的命令缩小到仅包含 outcome_type=Transfer

的文档

db.collection.createIndex( { breed: 1 } )

Answer 1

会是这个：

db.collection.createIndex(
   { breed: 1 },
   { partialFilterExpression: { outcome_type: 'Transfer' } }
)

如何为 mongodb 中的特定文档创建复合索引

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