可以在ArangoDB中编写查询来聚合关联文档中的值吗？_Arangodb

可以在ArangoDB中编写查询来聚合关联文档中的值吗？

arangodb

可以在ArangoDB中编写查询来聚合关联文档中的值吗？,arangodb,Arangodb,假设你有一个电影订阅服务，拥有普通和高级会员资格以下是由用户活动生成并作为文档存储在集合中的数据示例： [ { "eventType": "sessionInfo", "userType": "premium", "sessionGroupID": 1 }, { "eventType": "mediaPlay", "productSKU": "starwars", "sess

假设你有一个电影订阅服务，拥有普通和高级会员资格

以下是由用户活动生成并作为文档存储在集合中的数据示例：

[
    {
        "eventType": "sessionInfo",
        "userType": "premium",
        "sessionGroupID": 1
    },
    {
        "eventType": "mediaPlay",
        "productSKU": "starwars",
        "sessionGroupID": 1,
        "elapsed": 200
    },
    {
        "eventType": "sessionInfo",
        "userType": "premium",
        "sessionGroupID": 2
    },
    {
        "eventType": "mediaPlay",
        "productSKU": "xmen",
        "sessionGroupID": 2,
        "elapsed": 500
    },
    {
        "eventType": "sessionInfo",
        "userType": "normal",
        "sessionGroupID": 3
    },
    {
        "eventType": "mediaPlay",
        "productSKU": "xmen",
        "sessionGroupID": 3,
        "elapsed": 10
    },
    {
        "eventType": "sessionInfo",
        "userType": "normal",
        "sessionGroupID": 4
    },
    {
        "eventType": "mediaPlay",
        "productSKU": "xmen",
        "sessionGroupID": 4,
        "elapsed": 100
    },
    {
        "eventType": "sessionInfo",
        "userType": "normal",
        "sessionGroupID": 5
    },
    {
        "eventType": "mediaPlay",
        "productSKU": "xmen",
        "sessionGroupID": 5,
        "elapsed": 5
    },
    {
        "eventType": "mediaPlay",
        "productSKU": "starwars",
        "sessionGroupID": 5,
        "elapsed": 25
    }
]

您可以看到有两种“事件类型”：

“sessionInfo”文档，包含整个系统共有的信息用户会话
“mediaPlay”文档，用于存储一次播放的秒数电影被观看了

（每个“mediaPlay”事件都包含sessionGroupID，因此它可以与该会话关联。）

问题1: 如果总共有数千万个文档，您将如何编写一个按用户类型分组的查询，以总计每部电影的观看时间

所需的查询结果：

premium users - total of "elapsed":
    xmen: 500
    starwars: 200

normal users - total of "elapsed":
    xmen: 115
    starwars: 25

问题2: 如果数据的结构不适合这种查询，那么理想的结构是什么

例如，将“mediaPlay”事件作为嵌套数组嵌套在每个“sessionInfo”文档中是否更好

像这样

[
    {
        "eventType": "sessionInfo",
        "userType": "premium",
        "sessionGroupID": 1,
        "viewLog": [
            {
                "eventType": "mediaPlay",
                "productSKU": "starwars",
                "sessionGroupID": 1,
                "elapsed": 200
            }
        ]
    },
    {
        "eventType": "sessionInfo",
        "userType": "premium",
        "sessionGroupID": 2,
        "viewLog": [
            {
                "eventType": "mediaPlay",
                "productSKU": "xmen",
                "sessionGroupID": 2,
                "elapsed": 500
            }
        ]
    },
    {
        "eventType": "sessionInfo",
        "userType": "normal",
        "sessionGroupID": 3,
        "viewLog": [
            {
                "eventType": "mediaPlay",
                "productSKU": "xmen",
                "sessionGroupID": 3,
                "elapsed": 10
            }
        ]
    },
    {
        "eventType": "sessionInfo",
        "userType": "normal",
        "sessionGroupID": 4,
        "viewLog": [
            {
                "eventType": "mediaPlay",
                "productSKU": "xmen",
                "sessionGroupID": 4,
                "elapsed": 100
            }
        ]
    },
    {
        "eventType": "sessionInfo",
        "userType": "normal",
        "sessionGroupID": 5,
        "viewLog": [
            {
                "eventType": "mediaPlay",
                "productSKU": "xmen",
                "sessionGroupID": 5,
                "elapsed": 5
            },
            {
                "eventType": "mediaPlay",
                "productSKU": "starwars",
                "sessionGroupID": 5,
                "elapsed": 25
            }
        ]
    }
]

感谢您的指导和建议

下面的查询遍历集合并收集按用户类型分组的所有会话ID。然后，它创建一个子查询，该子查询迭代集合并收集所有电影和经过的时间总和，其中

eventType

为“mediaPlay”，收集的会话包含

sessionGroupID

@@coll

是一个包含集合名称的集合

FOR doc IN @@coll
  FILTER doc.eventType == "sessionInfo"
  COLLECT userTypes = doc.userType INTO sessions = doc.sessionGroupID
  RETURN {
    "userTypes" : userTypes,
    "movies" : (
      FOR event IN @@coll
        FILTER event.sessionGroupID IN sessions
        FILTER event.eventType == "mediaPlay"
        COLLECT movie = event.productSKU INTO elapsed = event.elapsed
        RETURN { "movie" : movie, "elapsed" : SUM(elapsed) }
      )
  }

此查询的结果是：

[
  {
    "userTypes": "normal",
    "movies": [
      {
        "movie": "starwars",
        "elapsed": 25
      },
      {
        "movie": "xmen",
        "elapsed": 115
      }
    ]
  },
  {
    "userTypes": "premium",
    "movies": [
      {
        "movie": "starwars",
        "elapsed": 200
      },
      {
        "movie": "xmen",
        "elapsed": 500
      }
    ]
  }
]

关于你的第二个问题。嵌套数组/对象不会优化此查询，但应将数据拆分为两个集合。每个

eventType

（例如，命名集合，如eventType

sessionInfo

和

mediaPlay

）。这减少了所需的筛选语句的数量，更重要的是，它允许您通过SessionInfo和mediaPlays单独查询，这大大提高了您的性能

然后，查询将如下所示：

FOR doc IN sessionInfo
  COLLECT userTypes = doc.userType INTO sessions = doc.sessionGroupID
  RETURN {
    "userTypes" : userTypes,
    "movies" : (
      FOR event IN mediaPlay
        FILTER event.sessionGroupID IN sessions
        COLLECT movie = event.productSKU INTO elapsed = event.elapsed
        RETURN { "movie" : movie, "elapsed" : SUM(elapsed) }
      )
  }

以下查询遍历集合并收集按用户类型分组的所有会话ID。然后，它创建一个子查询，该子查询迭代集合并收集所有电影和经过的时间总和，其中

eventType