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  1. Core Server
  2. SERVER-31760

Lookup sub-pipeline is not using index for equality match

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Details

    • Bug
    • Status: Closed
    • Major - P3
    • Resolution: Fixed
    • None
    • 3.6.3, 3.7.1
    • Aggregation Framework
    • None
    • MongoDB server version: 3.6.0-rc1
    • Fully Compatible
    • ALL
    • v3.6
    • Query 2017-11-13, Query 2017-12-04, Query 2017-12-18, Query 2018-01-01, Query 2018-01-15
    • 0

    Description

      I am doing following aggregation to join two collection using foreign pipeline.
      It seems match stage is not using index at all.

      db.blogpost.aggregate([
        { $lookup: { 
          from: 'comment', 
          let: { blogpost_id: "$_id" }, 
          pipeline: [ { 
             $match: { $expr: { $eq: [ "$blogpost.id", "$$blogpost_id"] } } 
          } ], 
          as: 'comments'
        }}
      ])
      

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              david.storch@mongodb.com David Storch
              naveenk Naveen
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              Dates

                Created:
                Updated:
                Resolved: