Improve querying fields exist in MongoDB

Question

I\'m in progress with estimation of MongoDB for our customers. Per requirements we need associate with some entity ent variable set of name-value pairs.

Answer 1

You can redesign your schema like this:

{
  pairs:[
  {k: "a", v: 5775},
  {k: "b", v: "b1"},
  ]
}

Then you indexing your key:

db.people.ensureIndex({"pairs.k" : 1})

After this you will able to search by exact match:

db.ent.find({'pairs.k':"a"})

In case you go with Sparse index and your current schema, proposed by @WesFreeman, you will need to create an index on each key you want to search. It can affect write performance or will be not acceptable if your keys are not static.