mongodb中的索引创建
一 索引的建立
索引的建立：是为了提升查询的速度
测试插入100000条数据到数据库中
for(i=0;i<100000;i++){
db.test.insert({name:'test'+i,age:i})
}
查询第1000名人员的信息并且进行显示
db.test.find({name:'test1000'})
{ "_id" : ObjectId("5f9561df1221b7ffcd13e3ca"), "name" : "test1000", "age" : 1000 }
查询程序执行的时间
db.test.find({name:'test100000'}).explain('executionStats')
{
"queryPlanner" : {
"plannerVersion" : 1,
"namespace" : "mydb.test",
"indexFilterSet" : false,
"parsedQuery" : {
"name" : {
"$eq" : "test1000"
}
},
"winningPlan" : {
"stage" : "FETCH",
"inputStage" : {
"stage" : "IXSCAN",
"keyPattern" : {
"name" : 1
},
"indexName" : "name_1",
"isMultiKey" : false,
"multiKeyPaths" : {
"name" : [ ]
},
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 2,
"direction" : "forward",
"indexBounds" : {
"name" : [
"[\"test1000\", \"test1000\"]"
]
}
}
},
"rejectedPlans" : [ ]
},
"executionStats" : {
"executionSuccess" : true,
"nReturned" : 1,
"executionTimeMillis" : 0,
"totalKeysExamined" : 1,
"totalDocsExamined" : 1,
"executionStages" : {
"stage" : "FETCH",
"nReturned" : 1,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 1,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"docsExamined" : 1,
"alreadyHasObj" : 0,
"inputStage" : {
"stage" : "IXSCAN",
"nReturned" : 1,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 1,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"keyPattern" : {
"name" : 1
},
"indexName" : "name_1",
"isMultiKey" : false,
"multiKeyPaths" : {
"name" : [ ]
},
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 2,
"direction" : "forward",
"indexBounds" : {
"name" : [
"[\"test1000\", \"test1000\"]"
]
},
"keysExamined" : 1,
"seeks" : 1,
"dupsTested" : 0,
"dupsDropped" : 0,
"seenInvalidated" : 0
}
}
},
"serverInfo" : {
"host" : "LAPTOP-TFVLBBKE",
"port" : 27017,
"version" : "3.4.6",
"gitVersion" : "c55eb86ef46ee7aede3b1e2a5d184a7df4bfb5b5"
},
"ok" : 1
}
设置索引加快查询时间和速度
