MongoDB Enterprise > db.test.drop() true MongoDB Enterprise > db.test.insert({a: 1}) WriteResult({ "nInserted" : 1 }) MongoDB Enterprise > db.test.createIndex({a: 1}) { "numIndexesBefore" : 1, "numIndexesAfter" : 2, "createdCollectionAutomatically" : false , "ok" : 1 } MongoDB Enterprise > db.test.createIndex({a: -1, b: 1}) { "numIndexesBefore" : 2, "numIndexesAfter" : 3, "createdCollectionAutomatically" : false , "ok" : 1 } // CBR not enabled yet MongoDB Enterprise > db.test.explain().find({a: {$in: [1, 3]}, b: {$in: [1, 3]}}).count() { "explainVersion" : "1" , "queryPlanner" : { "namespace" : "test.test" , "parsedQuery" : { "$and" : [ { "a" : { "$in" : [ 1, 3 ] } }, { "b" : { "$in" : [ 1, 3 ] } } ] }, "indexFilterSet" : false , "queryHash" : "851B3812" , "planCacheShapeHash" : "851B3812" , "planCacheKey" : "1B96FA17" , "optimizationTimeMillis" : 1, "maxIndexedOrSolutionsReached" : false , "maxIndexedAndSolutionsReached" : false , "maxScansToExplodeReached" : false , "prunedSimilarIndexes" : false , "winningPlan" : { "isCached" : false , "stage" : "COUNT" , "inputStage" : { "stage" : "IXSCAN" , "keyPattern" : { "a" : -1, "b" : 1 }, "indexName" : "a_-1_b_1" , "isMultiKey" : false , "multiKeyPaths" : { "a" : [ ], "b" : [ ] }, "isUnique" : false , "isSparse" : false , "isPartial" : false , "indexVersion" : 2, "direction" : "forward" , "indexBounds" : { "a" : [ "[3.0, 3.0]" , "[1.0, 1.0]" ], "b" : [ "[1.0, 1.0]" , "[3.0, 3.0]" ] } } }, "rejectedPlans" : [ { "isCached" : false , "stage" : "COUNT" , "inputStage" : { "stage" : "FETCH" , "filter" : { "b" : { "$in" : [ 1, 3 ] } }, "inputStage" : { "stage" : "IXSCAN" , "keyPattern" : { "a" : 1 }, "indexName" : "a_1" , "isMultiKey" : false , "multiKeyPaths" : { "a" : [ ] }, "isUnique" : false , "isSparse" : false , "isPartial" : false , "indexVersion" : 2, "direction" : "forward" , "indexBounds" : { "a" : [ "[1.0, 1.0]" , "[3.0, 3.0]" ] } } } } ] }, "command" : { "count" : "test" , "query" : { "a" : { "$in" : [ 1, 3 ] }, "b" : { "$in" : [ 1, 3 ] } } }, "serverInfo" : { "host" : "ip-10-122-11-12" , "port" : 27017, "version" : "8.3.0-alpha0" , "gitVersion" : "nogitversion" }, "serverParameters" : { "internalQueryFacetBufferSizeBytes" : 104857600, "internalDocumentSourceGroupMaxMemoryBytes" : 104857600, "internalQueryMaxBlockingSortMemoryUsageBytes" : 104857600, "internalDocumentSourceSetWindowFieldsMaxMemoryBytes" : 104857600, "internalQueryFacetMaxOutputDocSizeBytes" : 104857600, "internalLookupStageIntermediateDocumentMaxSizeBytes" : 104857600, "internalQueryProhibitBlockingMergeOnMongoS" : 0, "internalQueryMaxAddToSetBytes" : 104857600, "internalQueryFrameworkControl" : "trySbeRestricted" , "internalQueryPlannerIgnoreIndexWithCollationForRegex" : 1 }, "ok" : 1 } MongoDB Enterprise > db.adminCommand({setParameter: 1, planRankerMode: "samplingCE" }) { "was" : "multiPlanning" , "ok" : 1 } MongoDB Enterprise > db.test.explain().find({a: {$in: [1, 3]}, b: {$in: [1, 3]}}).count() { "explainVersion" : "1" , "queryPlanner" : { "namespace" : "test.test" , "parsedQuery" : { "$and" : [ { "a" : { "$in" : [ 1, 3 ] } }, { "b" : { "$in" : [ 1, 3 ] } } ] }, "indexFilterSet" : false , "queryHash" : "851B3812" , "planCacheShapeHash" : "851B3812" , "planCacheKey" : "1B96FA17" , "optimizationTimeMillis" : 0, "maxIndexedOrSolutionsReached" : false , "maxIndexedAndSolutionsReached" : false , "maxScansToExplodeReached" : false , "prunedSimilarIndexes" : false , "winningPlan" : { "isCached" : false , "stage" : "COUNT" , "inputStage" : { "stage" : "IXSCAN" , "costEstimate" : 0.0144587, "cardinalityEstimate" : 0, "numKeysEstimate" : 1, "estimatesMetadata" : { "ceSource" : "Sampling" }, "keyPattern" : { "a" : -1, "b" : 1 }, "indexName" : "a_-1_b_1" , "isMultiKey" : false , "multiKeyPaths" : { "a" : [ ], "b" : [ ] }, "isUnique" : false , "isSparse" : false , "isPartial" : false , "indexVersion" : 2, "direction" : "forward" , "indexBounds" : { "a" : [ "[3.0, 3.0]" , "[1.0, 1.0]" ], "b" : [ "[1.0, 1.0]" , "[3.0, 3.0]" ] } } }, "rejectedPlans" : [ { "isCached" : false , "stage" : "FETCH" , "costEstimate" : 0.0234674, "cardinalityEstimate" : 0, "estimatesMetadata" : { "ceSource" : "Sampling" }, "filter" : { "b" : { "$in" : [ 1, 3 ] } }, "inputStage" : { "stage" : "IXSCAN" , "costEstimate" : 0.0144587, "cardinalityEstimate" : 1, "numKeysEstimate" : 1, "estimatesMetadata" : { "ceSource" : "Sampling" }, "keyPattern" : { "a" : 1 }, "indexName" : "a_1" , "isMultiKey" : false , "multiKeyPaths" : { "a" : [ ] }, "isUnique" : false , "isSparse" : false , "isPartial" : false , "indexVersion" : 2, "direction" : "forward" , "indexBounds" : { "a" : [ "[1.0, 1.0]" , "[3.0, 3.0]" ] } } } ] }, "command" : { "count" : "test" , "query" : { "a" : { "$in" : [ 1, 3 ] }, "b" : { "$in" : [ 1, 3 ] } } }, "serverInfo" : { "host" : "ip-10-122-11-12" , "port" : 27017, "version" : "8.3.0-alpha0" , "gitVersion" : "nogitversion" }, "serverParameters" : { "internalQueryFacetBufferSizeBytes" : 104857600, "internalDocumentSourceGroupMaxMemoryBytes" : 104857600, "internalQueryMaxBlockingSortMemoryUsageBytes" : 104857600, "internalDocumentSourceSetWindowFieldsMaxMemoryBytes" : 104857600, "internalQueryFacetMaxOutputDocSizeBytes" : 104857600, "internalLookupStageIntermediateDocumentMaxSizeBytes" : 104857600, "internalQueryProhibitBlockingMergeOnMongoS" : 0, "internalQueryMaxAddToSetBytes" : 104857600, "internalQueryFrameworkControl" : "trySbeRestricted" , "internalQueryPlannerIgnoreIndexWithCollationForRegex" : 1 }, "ok" : 1 } MongoDB Enterprise >