Last point TS Opt M6: $topn(1) and/or $top

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    • Type: New Feature
    • Resolution: Fixed
    • Priority: Major - P3
    • 6.0.0-rc0
    • Affects Version/s: None
    • Component/s: None
    • None
    • Fully Compatible
    • None
    • 3
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      A query like this:

       

      db.coll.aggregate([
  {$group: {
    _id: "$meta.a",
     mostRecent: {$topN: {
       n: 1,
       sortBy: {ts: -1},
       output: {
         ts: "$ts",
         measureA: "$measureA",
         measureB: "$measureB"
       }
     }}
  }}
])

      or

      db.coll.aggregate([
  {$group: {
    _id: "$meta.a",
     mostRecent: {$top: {
       sortBy: {ts: -1},
       output: {
         ts: "$ts",
         measureA: "$measureA",
         measureB: "$measureB"
       }
     }}
  }}
])

      Will be rewritten to something like this to get the last point optimization:

      db.measurements.aggregate([
   {$sort: {"meta.a": 1, "ts": -1}},
   {$group: {
     _id: "$sensorId”,
     ts: {$first: "$ts”},
     measureA: {$first: "$measureA"},
     measureB: {$first: "$measureB"}
   }}
])

       

            Assignee:
            Alya Berciu
            Reporter:
            Ruslan Abdulkhalikov (Inactive)
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              Created:
              Updated:
              Resolved: