db.samplec.explain(true).aggregate(z)
{
	"stages" : [
		{
			"$cursor" : {
				"query" : {
					"$and" : [
						{
							"a" : {
								"$gte" : 500000
							}
						},
						{
							"a" : {
								"$lte" : 700000
							}
						}
					]
				},
				"queryPlanner" : {
					"plannerVersion" : 1,
					"namespace" : "test.samplec",
					"indexFilterSet" : false,
					"parsedQuery" : {
						"$and" : [
							{
								"a" : {
									"$lte" : 700000
								}
							},
							{
								"a" : {
									"$gte" : 500000
								}
							}
						]
					},
					"queryHash" : "847EC3FB",
					"planCacheKey" : "B9955400",
					"winningPlan" : {
						"stage" : "FETCH",
						"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" : [
									"[500000.0, 700000.0]"
								]
							}
						}
					},
					"rejectedPlans" : [ ]
				},
				"executionStats" : {
					"executionSuccess" : true,
					"nReturned" : 200001,
					"executionTimeMillis" : 321,
					"totalKeysExamined" : 200001,
					"totalDocsExamined" : 200001,
					"executionStages" : {
						"stage" : "FETCH",
						"nReturned" : 200001,
						"executionTimeMillisEstimate" : 2,
						"works" : 200002,
						"advanced" : 200001,
						"needTime" : 0,
						"needYield" : 0,
						"saveState" : 1575,
						"restoreState" : 1575,
						"isEOF" : 1,
						"docsExamined" : 200001,
						"alreadyHasObj" : 0,
						"inputStage" : {
							"stage" : "IXSCAN",
							"nReturned" : 200001,
							"executionTimeMillisEstimate" : 0,
							"works" : 200002,
							"advanced" : 200001,
							"needTime" : 0,
							"needYield" : 0,
							"saveState" : 1575,
							"restoreState" : 1575,
							"isEOF" : 1,
							"keyPattern" : {
								"a" : 1
							},
							"indexName" : "a_1",
							"isMultiKey" : false,
							"multiKeyPaths" : {
								"a" : [ ]
							},
							"isUnique" : false,
							"isSparse" : false,
							"isPartial" : false,
							"indexVersion" : 2,
							"direction" : "forward",
							"indexBounds" : {
								"a" : [
									"[500000.0, 700000.0]"
								]
							},
							"keysExamined" : 200001,
							"seeks" : 1,
							"dupsTested" : 0,
							"dupsDropped" : 0
						}
					},
					"allPlansExecution" : [ ]
				}
			}
		},
		{
			"$sample" : {
				"size" : NumberLong(25)
			}
		}
	],
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1570048933, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1570048933, 1)
}