查看MongoDB Quick Start的源代码

== Index ==

<source lang=bash>
> for (i=0; i<200000; i++){
... db.numbers.save({num:i});
... }
> db.numbers.count()
200000
> db.numbers.find()
{ "_id" : ObjectId("548ff09c991680933fb5a00b"), "num" : 0 }
{ "_id" : ObjectId("548ff09c991680933fb5a00c"), "num" : 1 }
{ "_id" : ObjectId("548ff09c991680933fb5a00d"), "num" : 2 }
{ "_id" : ObjectId("548ff09c991680933fb5a00e"), "num" : 3 }
{ "_id" : ObjectId("548ff09c991680933fb5a00f"), "num" : 4 }
{ "_id" : ObjectId("548ff09c991680933fb5a010"), "num" : 5 }
{ "_id" : ObjectId("548ff09c991680933fb5a011"), "num" : 6 }
{ "_id" : ObjectId("548ff09c991680933fb5a012"), "num" : 7 }
{ "_id" : ObjectId("548ff09c991680933fb5a013"), "num" : 8 }
{ "_id" : ObjectId("548ff09c991680933fb5a014"), "num" : 9 }
{ "_id" : ObjectId("548ff09c991680933fb5a015"), "num" : 10 }
{ "_id" : ObjectId("548ff09c991680933fb5a016"), "num" : 11 }
{ "_id" : ObjectId("548ff09c991680933fb5a017"), "num" : 12 }
{ "_id" : ObjectId("548ff09c991680933fb5a018"), "num" : 13 }
{ "_id" : ObjectId("548ff09c991680933fb5a019"), "num" : 14 }
{ "_id" : ObjectId("548ff09c991680933fb5a01a"), "num" : 15 }
{ "_id" : ObjectId("548ff09c991680933fb5a01b"), "num" : 16 }
{ "_id" : ObjectId("548ff09c991680933fb5a01c"), "num" : 17 }
{ "_id" : ObjectId("548ff09c991680933fb5a01d"), "num" : 18 }
{ "_id" : ObjectId("548ff09c991680933fb5a01e"), "num" : 19 }
has more
> it
{ "_id" : ObjectId("548ff09c991680933fb5a01f"), "num" : 20 }
{ "_id" : ObjectId("548ff09c991680933fb5a020"), "num" : 21 }
{ "_id" : ObjectId("548ff09c991680933fb5a021"), "num" : 22 }
{ "_id" : ObjectId("548ff09c991680933fb5a022"), "num" : 23 }
{ "_id" : ObjectId("548ff09c991680933fb5a023"), "num" : 24 }
{ "_id" : ObjectId("548ff09c991680933fb5a024"), "num" : 25 }
{ "_id" : ObjectId("548ff09c991680933fb5a025"), "num" : 26 }
{ "_id" : ObjectId("548ff09c991680933fb5a026"), "num" : 27 }
{ "_id" : ObjectId("548ff09c991680933fb5a027"), "num" : 28 }
{ "_id" : ObjectId("548ff09c991680933fb5a028"), "num" : 29 }
{ "_id" : ObjectId("548ff09c991680933fb5a029"), "num" : 30 }
{ "_id" : ObjectId("548ff09c991680933fb5a02a"), "num" : 31 }
{ "_id" : ObjectId("548ff09c991680933fb5a02b"), "num" : 32 }
{ "_id" : ObjectId("548ff09c991680933fb5a02c"), "num" : 33 }
{ "_id" : ObjectId("548ff09c991680933fb5a02d"), "num" : 34 }
{ "_id" : ObjectId("548ff09c991680933fb5a02e"), "num" : 35 }
{ "_id" : ObjectId("548ff09c991680933fb5a02f"), "num" : 36 }
{ "_id" : ObjectId("548ff09c991680933fb5a030"), "num" : 37 }
{ "_id" : ObjectId("548ff09c991680933fb5a031"), "num" : 38 }
{ "_id" : ObjectId("548ff09c991680933fb5a032"), "num" : 39 }
has more
> db.numbers.find({num:500})
{ "_id" : ObjectId("548ff09c991680933fb5a1ff"), "num" : 500 }
> db.numbers.find({num:{"$gt":199997}})
{ "_id" : ObjectId("548ff0b1991680933fb8ad49"), "num" : 199998 }
{ "_id" : ObjectId("548ff0b1991680933fb8ad4a"), "num" : 199999 }

> db.numbers.find({num:{"$gt":33,"$lt":36}})
{ "_id" : ObjectId("548ff09c991680933fb5a02d"), "num" : 34 }
{ "_id" : ObjectId("548ff09c991680933fb5a02e"), "num" : 35 }

> db.numbers.find({num:{"$gt":199997}}).explain()
{
        "cursor" : "BasicCursor",
        "indexBounds" : [ ],
        "nscanned" : 200000,
        "nscannedObjects" : 200000,
        "n" : 2,
        "millis" : 60,
        "oldPlan" : {
                "cursor" : "BasicCursor",
                "indexBounds" : [ ]
        },
        "allPlans" : [
                {
                        "cursor" : "BasicCursor",
                        "indexBounds" : [ ]
                }
        ]
}
</source>

Find a line, the time is 60ms


Use Indexes:

<source lang=bash>
> db.numbers.ensureIndex({num:1})
> db.numbers.getIndexes()
[
        {
                "name" : "_id_",
                "ns" : "test.numbers",
                "key" : {
                        "_id" : 1
                }
        },
        {
                "_id" : ObjectId("548ff1ea991680933fb8ad4b"),
                "ns" : "test.numbers",
                "key" : {
                        "num" : 1
                },
                "name" : "num_1"
        }
]
> db.numbers.find({num:{"$gt":199997}}).explain()
{
        "cursor" : "BtreeCursor num_1",
        "indexBounds" : [
                [
                        {
                                "num" : 199997
                        },
                        {
                                "num" : 1.7976931348623157e+308
                        }
                ]
        ],
        "nscanned" : 3,
        "nscannedObjects" : 2,
        "n" : 2,
        "millis" : 0,
        "allPlans" : [
                {
                        "cursor" : "BtreeCursor num_1",
                        "indexBounds" : [
                                [
                                        {
                                                "num" : 199997
                                        },
                                        {
                                                "num" : 1.7976931348623157e+308
                                        }
                                ]
                        ]
                }
        ]
}

</source>

The time is less than 1ms

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