Shulou(Shulou.com)06/01 Report--

In the test library of mongodb:

> 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"}});"

two。 Create an index on the field info:

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

Index query for 3.data table:

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. The use of the index:

The following query can use the index of info:

> 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"})

You can use query.explain () to view the use of the index:

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

}

But this kind of query doesn't work:

> db.data.find ({"info.city": "beijing"}); / / the fields must be in quotation marks

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

For such query statements, only similar composite indexes can be used:

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

5. Combinatorial index

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

Index scanning can be used even when querying, contrary to the sort defined.

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]"

]

}

}

}

"rejectedPlans": []

}

"serverInfo": {

"host": "mycentos.WORKGROUP"

"port": 27017

"version": "3.2.8"

"gitVersion": "ed70e33130c977bda0024c125b56d159573dbaf0"

}

"ok": 1

}

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