mongodb - mongodb 中相同的查询具有不同的执行时间

标签 mongodb

我已多次执行同一个查询，执行时间从大约一秒到超过 20 秒不等。

MongoDB 版本是 3.2.10。

下面是快速查询和慢速查询的解释方法的输出。

快速查询:

{
  "executionTimeMillis": 309,
  "allPlansExecution": [
    {
      "shardName": "sh001-rs",
      "allPlans": []
    }
  ],
  "totalKeysExamined": 18478,
  "nReturned": 15096,
  "executionStages": {
    "executionTimeMillis": 309,
    "shards": [
      {
        "shardName": "sh001-rs",
        "executionSuccess": true,
        "executionStages": {
          "needYield": 0,
          "docsExamined": 18378,
          "saveState": 144,
          "restoreState": 144,
          "isEOF": 1,
          "inputStage": {
            "saveState": 144,
            "isEOF": 1,
            "seenInvalidated": 0,
            "keysExamined": 18478,
            "nReturned": 18378,
            "invalidates": 0,
            "keyPattern": {
              "_id": 1
            },
            "isUnique": true,
            "needTime": 99,
            "isMultiKey": false,
            "executionTimeMillisEstimate": 30,
            "dupsTested": 0,
            "restoreState": 144,
            "direction": "forward",
            "indexName": "_id_",
            "isSparse": false,
            "advanced": 18378,
            "stage": "IXSCAN",
            "dupsDropped": 0,
            "needYield": 0,
            "isPartial": false,
            "indexBounds": {
              "_id": []
            },
            "works": 18478,
            "indexVersion": 1
          },
          "nReturned": 15096,
          "needTime": 3381,
          "filter": {
            "available": {
              "$gt": 0
            }
          },
          "executionTimeMillisEstimate": 180,
          "alreadyHasObj": 0,
          "invalidates": 0,
          "works": 18478,
          "advanced": 15096,
          "stage": "FETCH"
        }
      }
    ],
    "nReturned": 15096,
    "totalKeysExamined": 18478,
    "totalChildMillis": 251,
    "totalDocsExamined": 18378,
    "stage": "SINGLE_SHARD"
  },
  "totalDocsExamined": 18378
}

查询速度慢:

{
  "executionTimeMillis": 16139,
  "allPlansExecution": [
    {
      "shardName": "sh001-rs",
      "allPlans": []
    }
  ],
  "totalKeysExamined": 18478,
  "nReturned": 15096,
  "executionStages": {
    "executionTimeMillis": 16139,
    "shards": [
      {
        "shardName": "sh001-rs",
        "executionSuccess": true,
        "executionStages": {
          "needYield": 0,
          "docsExamined": 18378,
          "saveState": 677,
          "restoreState": 677,
          "isEOF": 1,
          "inputStage": {
            "saveState": 677,
            "isEOF": 1,
            "seenInvalidated": 0,
            "keysExamined": 18478,
            "nReturned": 18378,
            "invalidates": 0,
            "keyPattern": {
              "_id": 1
            },
            "isUnique": true,
            "needTime": 99,
            "isMultiKey": false,
            "executionTimeMillisEstimate": 270,
            "dupsTested": 0,
            "restoreState": 677,
            "direction": "forward",
            "indexName": "_id_",
            "isSparse": false,
            "advanced": 18378,
            "stage": "IXSCAN",
            "dupsDropped": 0,
            "needYield": 0,
            "isPartial": false,
            "indexBounds": {
              "_id": []
            },
            "works": 18478,
            "indexVersion": 1
          },
          "nReturned": 15096,
          "needTime": 3381,
          "filter": {
            "available": {
              "$gt": 0
            }
          },
          "executionTimeMillisEstimate": 14518,
          "alreadyHasObj": 0,
          "invalidates": 0,
          "works": 18478,
          "advanced": 15096,
          "stage": "FETCH"
        }
      }
    ],
    "nReturned": 15096,
    "totalKeysExamined": 18478,
    "totalChildMillis": 16076,
    "totalDocsExamined": 18378,
    "stage": "SINGLE_SHARD"
  },
  "totalDocsExamined": 18378
}

db.stats() 的结果:

{
    "raw" : {
        "sh001-rs/host101-prod:27017,host102-prod:27018" : {

            "db" : "records",
            "collections" : 2,
            "objects" : 124335,
            "avgObjSize" : 48253.87085695902,
            "dataSize" : 5999645033,
            "storageSize" : 5008375808,
            "numExtents" : 0,
            "indexes" : 17,
            "indexSize" : 17960960,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000018")
            }
        },
        "sh002-rs/host101-prod:27018,host102-prod:27017" : {

            "db" : "records",
            "collections" : 2,
            "objects" : 100643,
            "avgObjSize" : 58044.42780918693,
            "dataSize" : 5841765348,
            "storageSize" : 4884041728,
            "numExtents" : 0,
            "indexes" : 17,
            "indexSize" : 13737984,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000002")
            }
        },
        "sh003-rs/host103-prod:27017,host104-prod:27018" : {

            "db" : "records",
            "collections" : 2,
            "objects" : 191296,
            "avgObjSize" : 31400.14176459518,
            "dataSize" : 6006721519,
            "storageSize" : 5967814656,
            "numExtents" : 0,
            "indexes" : 17,
            "indexSize" : 32346112,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000012")
            }
        },
        "sh004-rs/host103-prod:27018,host104-prod:27017" : {

            "db" : "records",
            "collections" : 2,
            "objects" : 100904,
            "avgObjSize" : 58444.951716482996,
            "dataSize" : 5897329408,
            "storageSize" : 5684531200,
            "numExtents" : 0,
            "indexes" : 17,
            "indexSize" : 14114816,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff000000000000000c")
            }
        },
        "sh005-rs/host105-prod:27017,host106-prod:27018" : {

            "db" : "records",
            "collections" : 16,
            "objects" : 851626,
            "avgObjSize" : 10900.204212882181,
            "dataSize" : 9282897313,
            "storageSize" : 7225233408,
            "numExtents" : 0,
            "indexes" : 43,
            "indexSize" : 31690752,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff000000000000000e")
            }
        },
        "sh006-rs/host105-prod:27018,host106-prod:27017" : {

            "db" : "records",
            "collections" : 2,
            "objects" : 100946,
            "avgObjSize" : 58688.667386523484,
            "dataSize" : 5924386218,
            "storageSize" : 7723163648,
            "numExtents" : 0,
            "indexes" : 17,
            "indexSize" : 13565952,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000059")
            }
        },
        "sh007-rs/host107-prod:27017,host108-prod:27018" : {

            "db" : "records",
            "collections" : 2,
            "objects" : 100988,
            "avgObjSize" : 58563.519497366025,
            "dataSize" : 5914212707,
            "storageSize" : 4643889152,
            "numExtents" : 0,
            "indexes" : 17,
            "indexSize" : 14073856,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff000000000000000c")
            }
        },
        "sh008-rs/host107-prod:27018,host108-prod:27017" : {

            "db" : "records",
            "collections" : 2,
            "objects" : 100747,
            "avgObjSize" : 58695.07362005817,
            "dataSize" : 5913352582,
            "storageSize" : 4877357056,
            "numExtents" : 0,
            "indexes" : 17,
            "indexSize" : 13676544,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000002")
            }
        },
        "sh009-rs/host109-prod:27017,host110-prod:27018" : {

            "db" : "records",
            "collections" : 4,
            "objects" : 69101,
            "avgObjSize" : 152884.28821580007,
            "dataSize" : 10564457200,
            "storageSize" : 16441020352,
            "numExtents" : 32,
            "indexes" : 17,
            "indexSize" : 26171376,
            "fileSize" : 19251855360,
            "nsSizeMB" : 16,
            "extentFreeList" : {
                "num" : 0,
                "totalSize" : 0
            },
            "dataFileVersion" : {
                "major" : 4,
                "minor" : 22
            },
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000000")
            }
        },
        "sh010-rs/host110-prod:27017,host113-prod:27018" : {

            "db" : "records",
            "collections" : 4,
            "objects" : 69148,
            "avgObjSize" : 152176.07311852838,
            "dataSize" : 10522671104,
            "storageSize" : 16439971776,
            "numExtents" : 32,
            "indexes" : 17,
            "indexSize" : 26269488,
            "fileSize" : 19251855360,
            "nsSizeMB" : 16,
            "extentFreeList" : {
                "num" : 0,
                "totalSize" : 0
            },
            "dataFileVersion" : {
                "major" : 4,
                "minor" : 22
            },
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000002")
            }
        },
        "sh011-rs/host109-prod:27018,host111-prod:27017" : {

            "db" : "records",
            "collections" : 2,
            "objects" : 77687,
            "avgObjSize" : 75111.53102835738,
            "dataSize" : 5835189511,
            "storageSize" : 5171572736,
            "numExtents" : 0,
            "indexes" : 17,
            "indexSize" : 9543680,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000002")
            }
        },
        "sh012-rs/host114-prod:27017,host115-prod:27018" : {

            "db" : "records",
            "collections" : 4,
            "objects" : 91151,
            "avgObjSize" : 115459.23068315213,
            "dataSize" : 10524224336,
            "storageSize" : 16454213568,
            "numExtents" : 32,
            "indexes" : 17,
            "indexSize" : 42793184,
            "fileSize" : 19251855360,
            "nsSizeMB" : 16,
            "extentFreeList" : {
                "num" : 0,
                "totalSize" : 0
            },
            "dataFileVersion" : {
                "major" : 4,
                "minor" : 22
            },
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000028")
            }
        },
        "sh013-rs/host114-prod:27018,host115-prod:27017" : {

            "db" : "records",
            "collections" : 2,
            "objects" : 99992,
            "avgObjSize" : 58494.27406192495,
            "dataSize" : 5848959452,
            "storageSize" : 6180712448,
            "numExtents" : 0,
            "indexes" : 17,
            "indexSize" : 13615104,
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff00000000000000a5")
            }
        },
        "sh014-rs/host111-prod:27018,host113-prod:27017" : {

            "db" : "records",
            "collections" : 4,
            "objects" : 91498,
            "avgObjSize" : 114842.1660801329,
            "dataSize" : 10507828512,
            "storageSize" : 16454213568,
            "numExtents" : 32,
            "indexes" : 17,
            "indexSize" : 42646016,
            "fileSize" : 19251855360,
            "nsSizeMB" : 16,
            "extentFreeList" : {
                "num" : 0,
                "totalSize" : 0
            },
            "dataFileVersion" : {
                "major" : 4,
                "minor" : 22
            },
            "ok" : 1,
            "$gleStats" : {
                "lastOpTime" : Timestamp(0, 0),
                "electionId" : ObjectId("7fffffff0000000000000004")
            }
        }
    },
    "objects" : 2170062,
    "avgObjSize" : 48193.523844940835,
    "dataSize" : 104583640243,
    "storageSize" : 123156111104,
    "numExtents" : 128,
    "indexes" : 264,
    "indexSize" : 312205824,
    "fileSize" : 77007421440,
    "extentFreeList" : {
        "num" : 0,
        "totalSize" : 0
    },
    "ok" : 1
}

我注意到主要是“saveState”和“restoreState”的数量不同。造成执行时间差异的可能原因是什么？

提前致谢。

最佳答案

我不知道这是否足以作为您的答案，但运行相同的查询时可能会得到不同的数字。 取决于:

  • 您的服务器上目前正在发生多少其他操作
  • 是内存(RAM)中请求的文档，在本例中是索引。

Here您还可以找到 explain()

输出的文档

关于mongodb - mongodb 中相同的查询具有不同的执行时间，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47788504/

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