在 MongoDB 中获取所有具有最高价值的数据答案

【问题标题】：Getting all data with highest value in MongoDB在 MongoDB 中获取所有具有最高价值的数据
【发布时间】：2022-01-21 20:06:24
【问题描述】：

我在 MongoDB 5 中有一个名为“漏洞”的集合。它看起来像这样：

[
  { _id: "...", "project": 244, "scanner": "sonarqube", "version": 1 },
  { _id: "...", "project": 244, "scanner": "sonarqube", "version": 2 },
  { _id: "...", "project": 244, "scanner": "sonarqube", "version": 2 },
  { _id: "...", "project": 244, "scanner": "shellcheck", "version": 1 },
  { _id: "...", "project": 244, "scanner": "shellcheck", "version": 2 },
  { _id: "...", "project": 244, "scanner": "shellcheck", "version": 3 },
  { _id: "...", "project": 244, "scanner": "powershell", "version": 2 },
  { _id: "...", "project": 244, "scanner": "powershell", "version": 3 },
  { _id: "...", "project": 244, "scanner": "powershell", "version": 4 },
  { _id: "...", "project": 244, "scanner": "powershell", "version": 4 }
]

我想为每个扫描仪检索具有最高版本的文档。它应该返回：

[
  { _id: "...", "project": 244, "scanner": "sonarqube", "version": 2 },
  { _id: "...", "project": 244, "scanner": "sonarqube", "version": 2 },
  { _id: "...", "project": 244, "scanner": "shellcheck", "version": 3 },
  { _id: "...", "project": 244, "scanner": "powershell", "version": 4 },
  { _id: "...", "project": 244, "scanner": "powershell", "version": 4 }
]

我想只用一个查询来完成。

有什么建议吗？

非常感谢

【问题讨论】：

标签： database mongodb collections max aggregation

【解决方案1】：

  db.collection.aggregate([
   {
     $sort: {
           version: -1
           }
  },
  {
   $group: {
  _id: "$scanner",
  version: {
    $first: "$version"
  },
  test: {
    $push: {
      v: "$version",
      id: "$_id",
      p: "$project"
      }
     }
    }
  },
  {
   $project: {
     items: {
      $filter: {
        input: "$test",
        as: "item",
        cond: {
        $eq: [
          "$$item.v",
          "$version"
        ]
       }
      }
     }
   }
  },
   {
    $unwind: "$items"
   },
   {
    $project: {
     scanner: "$_id",
     _id: "$items.id",
     project: "$items.p",
     version: "$items.v"
    }
   }
  ])

解释：

按版本降序排列（排序）
按扫描仪分组，从每个版本的列表中取出第一个值并将所有值推送到测试数组中，以便我们适合在下一阶段进行过滤
从测试数组中只过滤我们需要的最大版本的元素
展开仅过滤最大值的测试数组
在最后的 $project 阶段，根据您需要的原始名称重命名字段

playground

【讨论】：