node.js - Mongo DB - What should I put to indexes? -

i have query .sort() , .select():

item.find({title: searchregexp}).lean().select('slug title poster').limit(50).sort('-_id') 

should put mongodb indexes:

1. query fields { title: 1 }
2. sort fields { _id: -1 })
3. select fields { slug: 1, title: 1, poster: 1 }

or them together? { title: 1, _id: -1, slug: 1, title: 1, poster: 1 }