Is it possible to aggregate Loki logs by day on Grafana? - elasticsearch

Question

I have a set of logs like this:
{"action": "action_a", "username": "user_1", "ts": "2021-09-10T02:18:14.103Z"}
{"action": "action_a", "username": "user_2", "ts": "2021-09-10T02:17:14.103Z"}
{"action": "action_a", "username": "user_1", "ts": "2021-09-09T02:16:14.103Z"}
{"action": "action_a", "username": "user_1", "ts": "2021-09-08T02:15:14.103Z"}
Is it possible to group the logs by date and username to get a count of unique users per day?
I currently have the following query:
sum by (username) (count_over_time({job="my-app"} | json | username != "" [$__range]))
This effectively gives me a pie chart of unique users for the current dashboard range. Instead, I would like a time-series to show the number of unique users per day (for the past 60 days, for example). In other words, the Daily Active Users (DAU).
With the above logs, I need something like:
{"2021-09-10": 2}
{"2021-09-09": 1}
{"2021-09-08": 1}
Is this possible with Loki or should I look to something like Elasticsearch instead?

Answer 1

To aggregate by day with LogQL, you can replace $__range with your desired time grouping interval.
E.g.
sum by (username) (
count_over_time(
{job="my-app"} | json | username != ""
[1d]) # <-- put your desired time interval here instead of $__range
)
You can then use a time series visualization to show you your data:
Useful links:
supported time intervals
LogQL metric queries documentation

Answer 2

Maybe creating a new label using label_format would do the trick?
Labels format expression
sum by (day) (
count_over_time({job="my-app"} | json | label_format day=`{{.ts| substr 0 10}}` | username != ""[$__range])
)