Incorrect results for $elemMatch-$not when index is hinted

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    • Query Optimization
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      const coll = db.coll;
coll.drop()
coll.insert({
    "_id" : 122,
    "a" : NumberInt(0)
})

const q = [
	{
		"$match" : {
			"a" : {
				"$elemMatch" : {
                    "$nin" : [ ]
				}
			}
		}
	},
	{
		"$project" : {
			"_id" : 0,
			"a" : 1
		}
	}
];

jsTestLog(coll.aggregate(q).toArray())
// [ ]
jsTestLog(coll.aggregate(q, {hint: '_id_'}).toArray())
// [ { "a" : 0 } ]
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      const coll = db.coll; coll.drop() coll.insert({ "_id" : 122, "a" : NumberInt(0) }) const q = [ { "$match" : { "a" : { "$elemMatch" : { "$nin" : [ ] } } } }, { "$project" : { "_id" : 0, "a" : 1 } } ]; jsTestLog(coll.aggregate(q).toArray()) // [ ] jsTestLog(coll.aggregate(q, {hint: '_id_' }).toArray()) // [ { "a" : 0 } ]
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      See repro above.

            Assignee:
            Alexander Ignatyev
            Reporter:
            Matt Boros
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              Created:
              Updated: