if count or match after lookup very slow

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    • Type: Improvement
    • Resolution: Done
    • Priority: Major - P3
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    • Affects Version/s: None
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      aggregate query like below very slow [{
      "$lookup": {
      "from": "a" ,
      "let":

      { "item": "b" }

      ,
      "pipeline": [
      {
      "$match": {
      "$expr": {
      "$and":[

      {"$eq": [ "$_id", "$$item" ]}

      ]
      }
      }
      },

      { "$limit":1 }

      ],
      "as": "tmp_item"
      }
      },

      { "$count":"count"}

      ]
      I must put $count or $match after $lookup because of use lookup's results

              Assignee:
              Unassigned
              Reporter:
              George Wang
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                Created:
                Updated:
                Resolved: