Using group by in DynamoDB
You can create 2 GSIs: 1 with date as hashKey, 1 with month as hashKey.
Those GSIs will point you to the rows of that month / of that day.
Then you can just query the GSI, get all the rows of that month/day, and do the aggregation on your own. 
Does that work for you?
Thanks!
Erben
For a project I have to use DynamoDB(aws) and python(with boto).
I have items with a date and I need to display the count grouped by date or by month.
Something like
by date of the month [1/2: 5, 2/2: 10, 3/2: 7, 4/2: 30, 5/2: 25, ...]
or 
by month of the year [January: 5, February: 10, March: 7, ...]