Partial index shouldn't do fetch on conditions that are true by the definition of the index

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    • Query Optimization
    • Fully Compatible
    • v7.0, v6.3, v6.0, v5.0, v4.4
    • QO 2023-03-06, QO 2023-03-20, QO 2023-04-03, QO 2023-04-17, QO 2023-05-01
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      db.xxx.ensureIndex({x:1},{partialFilterExpression:{bin:true}})

      > db.xxx.find({bin:true,x:1}).explain()
{
	"queryPlanner" : {
		"plannerVersion" : 1,
		"namespace" : "test.xxx",
		"indexFilterSet" : false,
		"parsedQuery" : {
			"$and" : [
				{"bin" : {"$eq" : true}},
				{"x" : {"$eq" : 1}}
			]
		},
		"winningPlan" : {
			"stage" : "FETCH",
			"filter" : {"bin" : {"$eq" : true}},
			"inputStage" : {
				"stage" : "IXSCAN",
				"keyPattern" : {"x" : 1},
				"indexName" : "x_1",
				"isMultiKey" : false,
				"multiKeyPaths" : { "x" : [ ] },
				"isUnique" : false,
				"isSparse" : false,
				"isPartial" : true,
				"indexVersion" : 2,
				"direction" : "forward",
				"indexBounds" : { "x" : [ "[1.0, 1.0]" 	] }
			}
		},
		"rejectedPlans" : [ ]
	},
	"serverInfo" : {
		"host" : "AD-MAC10G.local",
		"port" : 27017,
		"version" : "3.4.2",
		"gitVersion" : "3f76e40c105fc223b3e5aac3e20dcd026b83b38b"
	},
	"ok" : 1
}

      There's no need to do the FETCH with a check on bin:true since that condition is already satisfied by the index partial filterexpression

            Assignee:
            Milena Ivanova
            Reporter:
            Alexander Komyagin (Inactive)
            Votes:
            13 Vote for this issue
            Watchers:
            49 Start watching this issue

              Created:
              Updated:
              Resolved: