MongoDB group by date intervals

Question

I have a collection with datetime field and count filed:

{
    _id: null,
    datetime: new Date(),
    count: 1234
}
         


        

Answer 1

There are two different ways to do this. One is to issue a separate count() query for each of the ranges. This is pretty easy, and if the datetime field is indexed, it will be fast.

The second way is to combine them all into one query using a similar method as your SQL example. To do this, you need to use the aggregate() method, creating a pipeline of $project to create the 0 or 1 values for the new "last_day", "last_week", and "last_month" fields, and then use the $group operator to do the sums.