如何索引$和运算符超过$或运算符

Question

早上好。我有一些问题。我有这些领域：

name: "Mike",
city: "NY",
address: "something",
pets: ["dog", "cat"]

我创建了索引

db.person.ensureIndex({name: 1})
db.person.ensureIndex({city: 1})
db.person.ensureIndex({address: 1})
db.person.ensureIndex({pets: 1})

查询是

db.person.find({$and: [{$or: [{name: "Mike"}, {city: "CA"}]}, {pets: "dog"}]}).explain()

我没有得到B_tree查询..我得到了BasicCursor ......如何解决？

Answer 1

可能是升级MongoDB版本的时候了。使用v2.2.1我得到一个BTree游标。

> db.person.insert({name: "Mike", city: "NY", address: "something", pets: ["dog", "cat"]})
> db.person.ensureIndex({name: 1})
> db.person.ensureIndex({city: 1})
> db.person.ensureIndex({address: 1})
> db.person.ensureIndex({pets: 1})
> db.person.find({$and: [{$or: [{name: "Mike"}, {city: "CA"}]}, {pets: "dog"}]}).explain()
{
        "cursor" : "BtreeCursor pets_1",
        "isMultiKey" : true,
        "n" : 1,
        "nscannedObjects" : 1,
        "nscanned" : 1,
        "nscannedObjectsAllPlans" : 1,
        "nscannedAllPlans" : 1,
        "scanAndOrder" : false,
        "indexOnly" : false,
        "nYields" : 0,
        "nChunkSkips" : 0,
        "millis" : 0,
        "indexBounds" : {
                "pets" : [
                        [
                                "dog",
                                "dog"
                        ]
                ]
        }
}