MongoDB4.0 explain执行计划分析
queryPlanner
queryPlanner是现版本explain的默认模式，queryPlanner模式下并不会去真正进行query语句查询，而是针对query语句进行执行计划分析并选出winning plan。
{
"queryPlanner": {
"plannerVersion": NumberInt("1"),
"namespace": "energy_tool_gs_yanshi.pointData",//该查询所在的表
"indexFilterSet": false,
"parsedQuery": {//查询参数
"$and": [
{
"pointId": {
"$eq": "5d275157000dec2f15d926b0"
}
},
{
"timeStamp": {
"$lte": 1592971200
}
},
{
"timeStamp": {
"$gte": 1569919810
}
}
]
},
"winningPlan": {//查询优化器针对该query所返回的最优执行计划的详细内容。
"stage": "FETCH",//最优查询计划的状态，FETCH:根据索引查询、
"inputStage": {
"stage": "IXSCAN",//查询的子状态，此处是索引扫描
"keyPattern": {//扫描的索引内容
"pointId": 1,
"timeStamp": -1
},
"indexName": "pointId_1_timeStamp_-1",//走的索引名称
"isMultiKey": false,//如果索引建立在array上，此处将是true。
"multiKeyPaths": {
"pointId": [ ],
"timeStamp": [ ]
},
"isUnique": false,
"isSparse": false,
"isPartial": false,
"indexVersion": NumberInt("2"),
"direction": "forward",//此query的查询顺序，此处是forward，如果用了.sort({w:-1})将显示backward。
"indexBounds": {//索引包含的字段
"pointId": [
"[\"5d275157000dec2f15d926b0\", \"5d275157000dec2f15d926b0\"]"
],
"timeStamp": [
"[1592971200.0, 1569919810.0]"
]
}
}
},
"rejectedPlans": [//优化器拒绝的查询计划
{
"stage": "FETCH",
"filter": {
"pointId": {
"$eq": "5d275157000dec2f15d926b0"
}
},
"inputStage": {
"stage": "IXSCAN",
"keyPattern": {
"timeStamp": NumberInt("-1")
},
"indexName": "timeStamp",
"isMultiKey": false,
"multiKeyPaths": {
"timeStamp": [ ]
},
"isUnique": false,
"isSparse": false,
"isPartial": false,
"indexVersion": NumberInt("2"),
"direction": "forward",
"indexBounds": {
"timeStamp": [
"[1592971200.0, 1569919810.0]"
]
}
}
}
]
},
"serverInfo": {
"host": "gs-server-6829",
"port": NumberInt("27019"),
"version": "4.0.10",
"gitVersion": "c389e7f69f637f7a1ac3cc9fae843b635f20b766"
},
"ok": 1,
"operationTime": Timestamp(1593311102, 2),
"$clusterTime": {
"clusterTime": Timestamp(1593311102, 2),
"signature": {
"hash": BinData(0, "AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId": NumberLong("0")
}
}
}
executionStats
// 1
{
"queryPlanner": {
"plannerVersion": NumberInt("1"),
"namespace": "suzhou_0.pointData",
"indexFilterSet": false,
"parsedQuery": {
"$and": [
{
"pointId": {
"$eq": "5ecb61cde0a772db005a75ec"
}
},
{
"timeStamp": {
"$lte": 1592971200
}
},
{
"timeStamp": {
"$gte": 1569919810
}
}
]
},
"winningPlan": {
"stage": "FETCH",
"inputStage": {
"stage": "IXSCAN",
"keyPattern": {
"pointId": NumberInt("1"),
"timeStamp": NumberInt("-1")
},
"indexName": "pointId_1_timeStamp_-1",
"isMultiKey": false,
"multiKeyPaths": {
"pointId": [ ],
"timeStamp": [ ]
},
"isUnique": false,
"isSparse": false,
"isPartial": false,
"indexVersion": NumberInt("2"),
"direction": "forward",
"indexBounds": {
"pointId": [
"[\"5ecb61cde0a772db005a75ec\", \"5ecb61cde0a772db005a75ec\"]"
],
"timeStamp": [
"[1592971200.0, 1569919810.0]"
]
}
}
},
"rejectedPlans": [
{
"stage": "FETCH",
"filter": {
"$and": [
{
"timeStamp": {
"$lte": 1592971200
}
},
{
"timeStamp": {
"$gte": 1569919810
}
}
]
},
"inputStage": {
"stage": "IXSCAN",
"keyPattern": {
"pointId": NumberInt("1")
},
"indexName": "pointId_1",
"isMultiKey": false,
"multiKeyPaths": {
"pointId": [ ]
},
"isUnique": false,
"isSparse": false,
"isPartial": false,
"indexVersion": NumberInt("2"),
"direction": "forward",
"indexBounds": {
"pointId": [
"[\"5ecb61cde0a772db005a75ec\", \"5ecb61cde0a772db005a75ec\"]"
]
}
}
}
]
},
"executionStats": {
"executionSuccess": true,//是否执行成功
"nReturned": NumberInt("81470000"),//查询的返回条数
"executionTimeMillis": NumberInt("245522"),//查询计划选择和查询执行所需的总时间，单位为毫秒
"totalKeysExamined": NumberInt("81470000"),//索引扫描次数
"totalDocsExamined": NumberInt("81470000"),//文档扫描次数
"executionStages": {
"stage": "FETCH",//状态，根据索引扫描文档
"nReturned": NumberInt("81470000"),//查询的返回条数
"executionTimeMillisEstimate": NumberInt("75962"),//根据索引去查询数据的时间
"works": NumberInt("81470001"),//执行了多少个工作单元，查询过程会分解为不同的工作单元,例如，检查一个索引的key值，或者查询了一个文档等
"advanced": NumberInt("81470000"),//返回到父阶段的结果数
"needTime": NumberInt("0"),//
"needYield": NumberInt("0"),//存储层请求查询系统产生锁定的次数
"saveState": NumberInt("637673"),//查询阶段暂停处理并存储其当前执行状态的次数
"restoreState": NumberInt("637673"),//查询阶段恢复一个执行状态的次数
"isEOF": NumberInt("1"),//指定查询阶段是否已经结束,1为结束，0表示该阶段还有结果需要返回
"invalidates": NumberInt("0"),
"docsExamined": NumberInt("81470000"),//在查询执行阶段扫描的文档数。
"alreadyHasObj": NumberInt("0"),
"inputStage": {
"stage": "IXSCAN",
"nReturned": NumberInt("81470000"),
"executionTimeMillisEstimate": NumberInt("10246"),//扫描索引所用的时间
"works": NumberInt("81470001"),
"advanced": NumberInt("81470000"),
"needTime": NumberInt("0"),
"needYield": NumberInt("0"),
"saveState": NumberInt("637673"),
"restoreState": NumberInt("637673"),
"isEOF": NumberInt("1"),
"invalidates": NumberInt("0"),
"keyPattern": {
"pointId": NumberInt("1"),
"timeStamp": NumberInt("-1")
},
"indexName": "pointId_1_timeStamp_-1",
"isMultiKey": false,
"multiKeyPaths": {
"pointId": [ ],
"timeStamp": [ ]
},
"isUnique": false,
"isSparse": false,
"isPartial": false,
"indexVersion": NumberInt("2"),
"direction": "forward",
"indexBounds": {
"pointId": [
"[\"5ecb61cde0a772db005a75ec\", \"5ecb61cde0a772db005a75ec\"]"
],
"timeStamp": [
"[1592971200.0, 1569919810.0]"
]
},
"keysExamined": NumberInt("81470000"),//在查询过程中，检查索引的总数
"seeks": NumberInt("1"),
"dupsTested": NumberInt("0"),
"dupsDropped": NumberInt("0"),
"seenInvalidated": NumberInt("0")
}
}
},
"serverInfo": {
"host": "gs-server-6828",
"port": NumberInt("27019"),
"version": "4.0.10",
"gitVersion": "c389e7f69f637f7a1ac3cc9fae843b635f20b766"
},
"ok": 1,
"operationTime": Timestamp(1593310893, 1),
"$clusterTime": {
"clusterTime": Timestamp(1593310893, 1),
"signature": {
"hash": BinData(0, "AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId": NumberLong("0")
}
}
}