MongoDB version is 4.1.5 > db.version() 4.1.5 Create base collection, and its index. > db.base.createIndex({x:1}) { "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 } Explain sort query on base collection. It uses IXSCAN. > db.base.find({}).sort({x:1}).explain() { "queryPlanner" : { "plannerVersion" : 1, "namespace" : "test.base", "indexFilterSet" : false, "parsedQuery" : {   }, "queryHash" : "B7791BAD", "planCacheKey" : "B7791BAD", "winningPlan" : { "stage" : "FETCH", "inputStage" : { "stage" : "IXSCAN", "keyPattern" : { "x" : 1 }, "indexName" : "x_1", "isMultiKey" : false, "multiKeyPaths" : { "x" : [ ] }, "isUnique" : false, "isSparse" : false, "isPartial" : false, "indexVersion" : 2, "direction" : "forward", "indexBounds" : { "x" : [ "[MinKey, MaxKey]" ] } } }, "rejectedPlans" : [ ] }, "serverInfo" : { "host" : "8ab9c3a1df86", "port" : 27017, "version" : "4.1.5", "gitVersion" : "f3349bac21f200cf2f9854eb51b359d3cbee3617" }, "ok" : 1 } Create a view based on base collection > db.createView("view", "base", [{$project:{x:1}}]) { "ok" : 1 } Explain sort query on view collection. It uses COLLSCAN. > db.view.find({}).sort({x:1}).explain() { "stages" : [ { "$cursor" : { "query" : {   }, "fields" : { "x" : 1, "_id" : 1 }, "queryPlanner" : { "plannerVersion" : 1, "namespace" : "test.base", "indexFilterSet" : false, "parsedQuery" : {   }, "queryHash" : "8B3D4AB8", "planCacheKey" : "8B3D4AB8", "winningPlan" : { "stage" : "COLLSCAN", "direction" : "forward" }, "rejectedPlans" : [ ] } } }, { "$project" : { "_id" : true, "x" : true } }, { "$sort" : { "sortKey" : { "x" : 1 } } } ], "ok" : 1 }