MongoDB one query with multiple OR or multiple queries?

Question

Every user has a mobile number, and I want to check there are other users in my address book.

So I have 1000 numbers and I want to check if any of the is in the database, so my initial idea is that for each number I run a mongodb query:

for (var i=0; i < numbers.length; i++) {
  db.users.findOne({phoneNumber: numbers[i]});
}

however I have been suggested to do so:

db.users.find($or: numbers.map(function(number){return {phoneNumber: number}}));
// That would result into a
// db.users.find($or:[{phoneNumber: "123"}, {phoneNumber: "234"}...])

Now are the two equivalent? Is the second way more expensive?

JohnnyHK · Accepted Answer · 2014-02-08 18:51:44Z

4

Using $in would be the cleanest way to find the docs where phoneNumber appears in numbers:

db.users.find({phoneNumber: {$in: numbers}})

answered Feb 8, 2014 at 18:51

JohnnyHK

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3 Comments

piggyback Over a year ago

apparently if numbers.length == 500 it takes at least 30s

Neil Lunn Over a year ago

@haskellguy is that your own results or just heresay? At any rate $in will be more efficient than $or as the latter is exclusive. The main performance factor will be how many numbers you have in the array of the documents in the collection,

piggyback Over a year ago

what kind of complexity does $in has? assuming I have n documents and m elements in the array?

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