MongoDB 大数据技术之mongodb中在嵌套子文档的文档上面建立索引

一、给collection objectid赋自定义的值

MongoDB Enterprise > db.testid.insert({_id:{imsi:"4567890123",address:"测试数据"}})

MongoDB Enterprise > db.testid.createIndex({"_id.imsi":1})

MongoDB Enterprise > db.testid.createIndex({"_id.address":1})

MongoDB Enterprise > db.testid.createIndex({"_id:imsi":1,"_id.address":1})

MongoDB 大数据技术之mongodb中在嵌套子文档的文档上面建立索引

二、查询嵌套

MongoDB Enterprise > db.testid.find().pretty()
{ "_id" : { "imsi" : "4567890123", "address" : "测试数据" } }
{ "_id" : { "imsi" : "4567890123", "address" : "测试数据", "id" : 123 } }

MongoDB Enterprise > db.testid.find({"_id.imsi":"4567890123"})
{ "_id" : { "imsi" : "4567890123", "address" : "测试数据" } }
{ "_id" : { "imsi" : "4567890123", "address" : "测试数据", "id" : 123 } }

三、转载文章

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1.在mongodb的test库：

> db.data.insert({name:"1616",info:{url:"http://www.1616.net/",city:"beijing"}});

> db.data.insert({name:"hao123",info:{url:"http://www.hao123.com/",city:"beijing"}});

> db.data.insert({name:"ll4la",info:{url:"http://www.114la.com/",city:"dongguan"}});

2.对字段 info 创建索引：

> db.data.ensureIndex({info: 1});

3.data表的索引查询：

rs0:PRIMARY> db.data.getIndexes()

[

{

"v" : 1,

"key" : {

"_id" : 1

"name" : "_id_",

"ns" : "test.data"

{

"v" : 1,

"key" : {

"info" : 1

"name" : "info_1",

"ns" : "test.data"

}

]

4.索引的用法：

以下查询是可以用到info的索引的：

>db.data.find({info: {url:"http://www.1616.net/", city:"beijing"}});

>db.data.find({info: {url:"http://www.1616.net/"} });

>db.data.find({info: {city:"beijing"});

可以使用query.explain()查看索引的使用：

rs0:PRIMARY> db.data.find({info: {city:"beijing"}}).explain()

{

"queryPlanner" : {

"plannerVersion" : 1,

"namespace" : "test.data",

"indexFilterSet" : false,

"parsedQuery" : {

"info" : {

"$eq" : {

"city" : "beijing"

}

"winningPlan" : {

"stage" : "FETCH",

"inputStage" : {

"stage" : "IXSCAN",

"keyPattern" : {

"info" : 1

"indexName" : "info_1",

"isMultiKey" : false,

"isUnique" : false,

"isSparse" : false,

"isPartial" : false,

"indexVersion" : 1,

"direction" : "forward",

"indexBounds" : {

"info" : [

"[{ city: \"beijing\" }, { city: \"beijing\" }]"

]

}

"rejectedPlans" : [ ]

"serverInfo" : {

"host" : "mycentos.WORKGROUP",

"port" : 27017,

"version" : "3.2.8",

"gitVersion" : "ed70e33130c977bda0024c125b56d159573dbaf0"

"ok" : 1

}

但是这样的查询就不行：

>db.data.find({"info.city":"beijing"}); //字段部分必须加引号

>db.data.find({info.url:"..."});

这样的查询语句，只能使用类似的组合索引：

> db.data.ensureIndex({"info.url":1, "info.city":1});

5.组合索引

> db.data.ensureIndex({"info.url":1, "info.city":1});

即使查询时，与定义的排序相反，也是可以使用索引扫描的。

rs0:PRIMARY> db.data.find({"info.url": /http:*/i}).sort({"info.url": -1, "info.city":-1}).explain()

{

"queryPlanner" : {

"plannerVersion" : 1,

"namespace" : "test.data",

"indexFilterSet" : false,

"parsedQuery" : {

"info.url" : /http:*/i

"winningPlan" : {

"stage" : "FETCH",

"inputStage" : {

"stage" : "IXSCAN",

"filter" : {

"info.url" : /http:*/i

"keyPattern" : {

"info.url" : 1,

"info.city" : 1

"indexName" : "info.url_1_info.city_1",

"isMultiKey" : false,

"isUnique" : false,

"isSparse" : false,

"isPartial" : false,

"indexVersion" : 1,

"direction" : "backward",

"indexBounds" : {

"info.url" : [

"[/http:*/i, /http:*/i]",

"({}, \"\"]"

"info.city" : [

"[MaxKey, MinKey]"

]

}