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我需要有关嵌套对象数组的查询优化的帮助。

我们有大量文档的集合，每个文档都包含嵌套的对象数组，最高可达 3 级，如下所示：

集合名称：产品

收集的文件总数：2000万

每个文档的大小：> = 500 kb

[
    {
        "_id":"ObjectId('121212')",
        "id":999,
        "name":"prod1",
        "sellers":[
            {
                "seller_id":99,
                "name":"Business 1",
                "providers":[
                    {
                        "seller_id":99,
                        "provider_id":1,
                        "provider_name":"prov 1",
                        "quantity":50,
                        "order_allowed":40,
                        "notification_on_stock":true
                    },
                    {
                        "seller_id":99,
                        "provider_id":2,
                        "provider_name":"prov 2",
                        "quantity":20,
                        "order_allowed":20,
                        "notification_on_stock":true
                    }
                ]
            },
            {
                "seller_id":9,
                "name":"Business 2",
                "providers":[
                    {
                        "seller_id":9,
                        "provider_id":3,
                        "provider_name":"prov 3",
                        "quantity":50,
                        "order_allowed":40,
                        "notification_on_stock":true
                    },
                    {
                        "seller_id":9,
                        "provider_id":4,
                        "provider_name":"prov 4",
                        "quantity":20,
                        "order_allowed":20,
                        "notification_on_stock":true
                    }
                ]
            }
        ]
    },
    {
        "_id":"ObjectId('232323')",
        "id":1000,
        "name":"prod 2",
        "sellers":[
            {
                "seller_id":44,
                "product_id":2,
                "name":"Business 22",
                "providers":[
                    {
                        "seller_id":44,
                        "provider_id":3,
                        "provider_name":"prov 3",
                        "quantity":50,
                        "order_allowed":40,
                        "notification_on_stock":true
                    },
                    {
                        "seller_id":44,
                        "provider_id":4,
                        "provider_name":"prov 4",
                        "quantity":20,
                        "order_allowed":20,
                        "notification_on_stock":true
                    }
                ]
            },
            {
                "seller_id":91,
                "name":"Business 21",
                "providers":[
                    {
                        "seller_id":91,
                        "provider_id":1,
                        "provider_name":"prov 1",
                        "quantity":50,
                        "order_allowed":40,
                        "notification_on_stock":true
                    },
                    {
                        "seller_id":91,
                        "provider_id":2,
                        "provider_name":"prov 2",
                        "quantity":20,
                        "order_allowed":20,
                        "notification_on_stock":true
                    }
                ]
            }
        ]
    },
    {
        "_id":"ObjectId('989798')",
        "id":1001,
        "name":"prod 3",
        "sellers":[
            {
                "seller_id":33,
                "name":"Business 112",
                "providers":[
                    {
                        "seller_id":33,
                        "provider_id":1,
                        "provider_name":"prov 1",
                        "quantity":50,
                        "order_allowed":40,
                        "notification_on_stock":true
                    },
                    {
                        "seller_id":33,
                        "provider_id":2,
                        "provider_name":"prov 2",
                        "quantity":20,
                        "order_allowed":20,
                        "notification_on_stock":true
                    }
                ]
            },
            {
                "seller_id":32,
                "name":"Business 2",
                "providers":[
                    {
                        "seller_id":32,
                        "provider_id":1,
                        "provider_name":"prov 1",
                        "quantity":50,
                        "order_allowed":40,
                        "notification_on_stock":true
                    },
                    {
                        "seller_id":32,
                        "provider_id":2,
                        "provider_name":"prov 2",
                        "quantity":20,
                        "order_allowed":20,
                        "notification_on_stock":true
                    }
                ]
            }
        ]
    }
]

我为我的产品系列添加了以下索引，如下所示，

  1. products.id 上的索引

    {“身份证”：1}

  2. 嵌套数组文档的索引

    { "products.sellers.seller_id":1 }

{
    "id":1,
    "sellers.seller_id":1,
    "sellers.providers.provider_id":1
}

我的查询：

db.products.find({
    "id":999,
    "sellers":{
        "$elemMatch":{
            "providers":{
                "$elemMatch":{
                    "seller_id":30098,
                    "provider_id":517
                }
            }
        }
    }
});

我的问题是查询总是在字段 id 上获取第一个索引，并且查询花费了大约 800 毫秒的时间，我需要对其进行优化。

4

1 回答 1

0

您的第三个复合索引将显示在拒绝计划中，因为您的条件与您的复合索引不同，

您正在匹配seller_id，provides但提供索引在selles.seller_id

我不确定根据您的要求什么是正确的，但请选择以下之一以实现获胜计划中的指标，

  1. 要么你的查询是错误的，你应该把它改成这个，
db.products.find({
    "id":999,
    "sellers":{
        "$elemMatch":{
            "seller_id":30098,
            "providers":{
                "$elemMatch":{
                    "provider_id":517
                }
            }
        }
    }
});
  1. 要么你创建了错误的索引，你应该更正它，
{
    "id":1,
    "sellers.providers.seller_id":1,
    "sellers.providers.provider_id":1
}

其次，我注意到您创建了错误的索引，我products在您的文档中看不到任何键，

  1. 嵌套数组文档的索引

    { "products.sellers.seller_id":1 }

于 2021-03-01T18:30:25.427 回答