Mongoose / MongoDB batchSize（30）仍返回所有结果

Question

The following query returns all my users. I was hoping it would be batched.

statics.findAllUsers = function findAllUsers(callback) {
  this.find({}, callback).batchSize(30);
};

Answer 1

batchSize() instructs the driver to retrieve a certain number of items per time. It'll still get everything from the DB, only a batch at a time.

To make it clearer: If you use batchSize(30) then it'll ask for 30 items then, when you need the 31st, it'll query the next 30 and so forth.

If you need only that number of items, then use limit() (and offset() to set which is the first item)

Docs: http://docs.mongodb.org/manual/reference/method/cursor.batchSize/