Does Key order matter in a MongoDB BSON doc?

问题

I know certain commends need the hashmap / dictionary to be ordered, but does the actual BSON document in MongoDB matter and would the index still work?

E.g.

db.people.ensureIndex({LName:1, FName:1});

Would it work on both:

{LName:"abc", FName:"def"}, 
{FName:"ghi", LName:"jkl"} 

?

Thanks

回答1:

The order of a document's properties does not affect indexing.

You can see this for yourself by running this query:

db.people.find({LName: "abc"}).explain()

and then this query:

db.people.find({LName: "jkl"}).explain()

you should see that MongoDB will use the index in both cases (the cursor property should be something like "BtreeCursor LName_1_FName_1").

来源：https://stackoverflow.com/questions/4453424/does-key-order-matter-in-a-mongodb-bson-doc