Ecto.Query.WindowAPI.ntile

You're seeing just the function ntile, go back to Ecto.Query.WindowAPI module for more information.

Returns integer ranging from 1 to the argument value, dividing the partition as equally as possible.

from p in Post,
     select: ntile(10) |> over(partition_by: p.category_id, order_by: p.date)

Note that this function must be invoked using window function syntax.