db.collection.explain().count() does not respect hint option

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    • Type: Bug
    • Resolution: Done
    • Priority: Major - P3
    • 3.3.14
    • Affects Version/s: 3.2.0
    • Component/s: Querying, Shell
    • Fully Compatible
    • ALL
    • Hide 
      db.testcounthint.insert({a:1, b:1, c:1});
db.testcounthint.insert({a:1, b:2, c:2});
db.testcounthint.insert({a:2, b:1, c:3});
db.testcounthint.insert({a:2, b:2, c:4});
db.testcounthint.createIndex({a:1, b:1})
db.testcounthint.createIndex({b:1, a:1})
db.testcounthint.createIndex({a:1, b:1, c:1})
db.testcounthint.explain().count({a:1, b:2}, {hint: "a_1_b_1_c_1"})
      Show
      db.testcounthint.insert({a:1, b:1, c:1}); db.testcounthint.insert({a:1, b:2, c:2}); db.testcounthint.insert({a:2, b:1, c:3}); db.testcounthint.insert({a:2, b:2, c:4}); db.testcounthint.createIndex({a:1, b:1}) db.testcounthint.createIndex({b:1, a:1}) db.testcounthint.createIndex({a:1, b:1, c:1}) db.testcounthint.explain().count({a:1, b:2}, {hint: "a_1_b_1_c_1"})
    • Query 2016-09-19
    • None
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      The following command generates a plan that does not utilize the a_1_b_1_c_1 index.

      > db.testcounthint.explain().count({a:1, b:2}, {hint: "a_1_b_1_c_1"})
{
	"queryPlanner" : {
		"plannerVersion" : 1,
		"namespace" : "test.testcounthint",
		"indexFilterSet" : false,
		"parsedQuery" : {
			"$and" : [
				{
					"a" : {
						"$eq" : 1
					}
				},
				{
					"b" : {
						"$eq" : 2
					}
				}
			]
		},
		"winningPlan" : {
			"stage" : "COUNT",
			"inputStage" : {
				"stage" : "COUNT_SCAN",
				"keyPattern" : {
					"b" : 1,
					"a" : 1
				},
				"indexName" : "b_1_a_1",
				"isMultiKey" : false,
				"isUnique" : false,
				"isSparse" : false,
				"isPartial" : false,
				"indexVersion" : 1
			}
		},
		"rejectedPlans" : [ ]
	},
	"serverInfo" : {
		"host" : "grey.local",
		"port" : 27017,
		"version" : "3.2.5",
		"gitVersion" : "34e65e5383f7ea1726332cb175b73077ec4a1b02"
	},
	"ok" : 1
}

      Please note that without the explain, the correct plan is generated.

      db.testcounthint.count({a:1, b:2}, {hint: "a_1_b_1_c_1"})

      Additionally, note that the following command with explain generates the correct plan:

      > db.testcounthint.explain().find({a:1,b:2}).hint("a_1_b_1_c_1").count()
{
	"queryPlanner" : {
		"plannerVersion" : 1,
		"namespace" : "test.testcounthint",
		"indexFilterSet" : false,
		"parsedQuery" : {
			"$and" : [
				{
					"a" : {
						"$eq" : 1
					}
				},
				{
					"b" : {
						"$eq" : 2
					}
				}
			]
		},
		"winningPlan" : {
			"stage" : "COUNT",
			"inputStage" : {
				"stage" : "COUNT_SCAN",
				"keyPattern" : {
					"a" : 1,
					"b" : 1,
					"c" : 1
				},
				"indexName" : "a_1_b_1_c_1",
				"isMultiKey" : false,
				"isUnique" : false,
				"isSparse" : false,
				"isPartial" : false,
				"indexVersion" : 1
			}
		},
		"rejectedPlans" : [ ]
	},
	"serverInfo" : {
		"host" : "grey.local",
		"port" : 27017,
		"version" : "3.2.5",
		"gitVersion" : "34e65e5383f7ea1726332cb175b73077ec4a1b02"
	},
	"ok" : 1
}

            Assignee:
            Maria van Keulen
            Reporter:
            Kelsey Schubert
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            0 Vote for this issue
            Watchers:
            6 Start watching this issue

              Created:
              Updated:
              Resolved: