{
	"explainVersion" : "1",
	"stages" : [
		{
			"$cursor" : {
				"queryPlanner" : {
					"namespace" : "test.xxx",
					"indexFilterSet" : false,
					"parsedQuery" : {
						"a" : {
							"$not" : {
								"$eq" : 2
							}
						}
					},
					"queryHash" : "6C205A8F",
					"planCacheKey" : "63384EA0",
					"optimizationTimeMillis" : 1,
					"maxIndexedOrSolutionsReached" : false,
					"maxIndexedAndSolutionsReached" : false,
					"maxScansToExplodeReached" : false,
					"prunedSimilarIndexes" : false,
					"winningPlan" : {
						"isCached" : false,
						"stage" : "PROJECTION_COVERED",
						"transformBy" : {
							"b" : 1,
							"_id" : 0
						},
						"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" : [
									"[MinKey, 2.0)",
									"(2.0, MaxKey]"
								],
								"b" : [
									"[MinKey, MaxKey]"
								]
							}
						}
					},
					"rejectedPlans" : [ ]
				},
				"executionStats" : {
					"executionSuccess" : true,
					"nReturned" : 3,
					"executionTimeMillis" : 3,
					"totalKeysExamined" : 4,
					"totalDocsExamined" : 0,
					"executionStages" : {
						"isCached" : false,
						"stage" : "PROJECTION_COVERED",
						"nReturned" : 3,
						"executionTimeMillisEstimate" : 0,
						"works" : 5,
						"advanced" : 3,
						"needTime" : 1,
						"needYield" : 0,
						"saveState" : 1,
						"restoreState" : 1,
						"isEOF" : 1,
						"transformBy" : {
							"b" : 1,
							"_id" : 0
						},
						"inputStage" : {
							"stage" : "IXSCAN",
							"nReturned" : 3,
							"executionTimeMillisEstimate" : 0,
							"works" : 5,
							"advanced" : 3,
							"needTime" : 1,
							"needYield" : 0,
							"saveState" : 1,
							"restoreState" : 1,
							"isEOF" : 1,
							"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" : [
									"[MinKey, 2.0)",
									"(2.0, MaxKey]"
								],
								"b" : [
									"[MinKey, MaxKey]"
								]
							},
							"keysExamined" : 4,
							"seeks" : 2,
							"dupsTested" : 0,
							"dupsDropped" : 0
						}
					}
				}
			},
			"nReturned" : NumberLong(3),
			"executionTimeMillisEstimate" : NumberLong(3)
		},
		{
			"$match" : {
				"b" : {
					"$not" : {
						"$exists" : true
					}
				}
			},
			"nReturned" : NumberLong(0),
			"executionTimeMillisEstimate" : NumberLong(3)
		},
		{
			"$group" : {
				"_id" : {
					"$const" : null
				},
				"a" : {
					"$sum" : {
						"$const" : 1
					}
				}
			},
			"maxAccumulatorMemoryUsageBytes" : {
				"a" : NumberLong(0)
			},
			"totalOutputDataSizeBytes" : NumberLong(0),
			"usedDisk" : false,
			"spills" : NumberLong(0),
			"spilledDataStorageSize" : NumberLong(0),
			"numBytesSpilledEstimate" : NumberLong(0),
			"spilledRecords" : NumberLong(0),
			"nReturned" : NumberLong(0),
			"executionTimeMillisEstimate" : NumberLong(3)
		},
		{
			"$project" : {
				"a" : true,
				"_id" : false
			},
			"nReturned" : NumberLong(0),
			"executionTimeMillisEstimate" : NumberLong(3)
		}
	],
	"serverInfo" : {
		"host" : "ip-10-0-106-40",
		"port" : 27017,
		"version" : "8.0.0-alpha",
		"gitVersion" : "2303b0fec38ba62b6199cd9e83932edd89c61fab"
	},
	"serverParameters" : {
		"internalQueryFacetBufferSizeBytes" : 104857600,
		"internalQueryFacetMaxOutputDocSizeBytes" : 104857600,
		"internalLookupStageIntermediateDocumentMaxSizeBytes" : 104857600,
		"internalDocumentSourceGroupMaxMemoryBytes" : 104857600,
		"internalQueryMaxBlockingSortMemoryUsageBytes" : 104857600,
		"internalQueryProhibitBlockingMergeOnMongoS" : 0,
		"internalQueryMaxAddToSetBytes" : 104857600,
		"internalDocumentSourceSetWindowFieldsMaxMemoryBytes" : 104857600,
		"internalQueryFrameworkControl" : "forceClassicEngine"
	},
	"command" : {
		"aggregate" : "xxx",
		"pipeline" : [
			{
				"$match" : {
					"a" : {
						"$ne" : 2
					}
				}
			},
			{
				"$match" : {
					"b" : {
						"$exists" : false
					}
				}
			},
			{
				"$count" : "a"
			}
		],
		"cursor" : {
			
		},
		"$db" : "test"
	},
	"ok" : 1
}