it doesn’t strike me as a great idea to write non-EL data into the log DB. Can we host these tables into prod or staging instead? You’ll be able to perform UNIONS with tables in log.

I think the plan is to change this EL instance to log the event "this user has now made X edits within their first 30 days", where X is in {1, 5, 10, 25, 50, 100}. That will start happening when this patch: https://gerrit.wikimedia.org/r/#/c/98079/1/WikimediaEvents.php is merged. So my idea is to backfill these milestone events so new the query can just be:

select month, count(*)

from EL_table

where event = 'NewEditorMilestone'

and milestone = 5

group by month