Question

我已经使用不同的组合进行了一段时间的研究 Mongodb聚合管道中的$ project，$ match，$ unwind。我的数据就像：

{
    "flow":[
        {"y":1},
        {"y":69696},
        {"y":3}
    ]
}
{
    "flow":[
        {"y":4},
        {"y":69632},
        {"y":6},
        {"y":7},
        {"y":8}
    ]
}

我想根据flow.y是否设置了第16位来对流数组元素进行分组。我想返回值的总和（不设置位）和匹配元素的计数。因此，对于上面的示例，我想检索：

[  
   {  "bitset": {
              "_id":null,
              "count":2,
              "y_total":8256
          },
       "bitunset": {
              "_id":null,
              "count":6,
              "y_total":29
          },
   }
]

我可以在两个单独的聚合调用中检索信息，但希望将它们组合在一起。

db.collection.aggregate([
  {$unwind: {path: "$flow"}},
  {$match: {"flow.y": { $bitsAllSet: 65536 }}},
  {$group: {
    _id: null,
    count: { $sum: 1 },
    y_total: {$sum: "$flow.y"}
  }}

我也尝试过：

db.collection.aggregate([
  {$unwind: {path: "$flow"}},
  {$match: {$or: [{"flow.y": { $bitsAllSet: 65536 }},
                  {"flow.y": { $bitsAllClear: 65536 }}]}},
  {$group: {
    _id: null,
    count: { $sum: 1 },
    y_total: {$sum: "$flow.y"}
  }}

如果我可以别名$ or运算符的结果，那会很好。 数据库版本v3.6.5

Answer 1

这是基于$facet的解决方案：

db.collection.aggregate([{
    $unwind: "$flow"
}, {
    $facet: {
        "bitset": [{
                $match: { "flow.y": { $bitsAllSet: 65536 } }
            }, {
                $group: {
                    _id: null,
                    count: { $sum: 1 },
                    y_total: {$sum: {$subtract: [ "$flow.y", 65536 ] }}
                }
            }
        ],
        "bitunset": [{
                $match: { "flow.y": { $bitsAllClear: 65536 } }
            }, {
                $group: {
                    _id: null,
                    count: { $sum: 1 },
                    y_total: { $sum: "$flow.y" }
                }
            }
        ]
    }
}])

或者没有$group阶段：

db.collection.aggregate([{
    $unwind: "$flow"
}, {
    $facet: {
        "bitset": [{
                $match: { "flow.y": { $bitsAllSet: 65536 } }
            }
        ],
        "bitunset": [{
                $match: { "flow.y": { $bitsAllClear: 65536 } }
            }
        ]
    }
}, {
    $project: {
        y_count_set: { $size: "$bitset.flow.y" },
        y_total_set: { $subtract: [ { $sum: "$bitset.flow.y" }, { $multiply: [ { $size: "$bitset.flow.y" }, 65536 ] } ] },
        y_count_unset: { $size: "$bitunset.flow.y" },
        y_total_unset: { $sum: "$bitunset.flow.y" }
    }
}])

在单个字段上别名多个$ match条件

1 个答案: