Is it slow/poor form to use the $in
operator in MongoDB with a large array of possibilities?
posts.find({
author : {
$in : ['friend1','friend2','friend3'....'friend40']
}
})
App Engine, for example, won't let you use more than 30 because they translate directly to one query per item in the IN array, and so instead force you into using their method for handling fan out. While that's probably the most efficient method in Mongo too, the code for it is significantly more complex so I'd prefer to just use this generic method.
Will Mongo execute these $in
queries efficiently for reasonable-sized datasets?