Just a heads up so others can avoid similar scares: Heroku gives 7 days' notice before deleting databases on their Hobby Basic tier once they exceed >10GB or >10m rows. [1]
Hobby Basic tier is meant for “Small side projects and proof-of-concepts”[2]. It's possible for a startup to spend a lot of time in this tier because it spans from tiny (10,000 rows, to quite large 10m rows). I suspect many startups reach $m valuations with smaller databases.
So what happened to:
> “Anything that can go wrong will go wrong.”
If your db admin's takes a week's holidays, they could return to quite a surprise.
Unexpected growth could push your db past its limits earlier than anticipated and an alert email could easily be missed.
Heroku's own infrastructure could go down at an inopportune time, preventing maintenance. For example heroku's database metrics page is currently not displaying database metrics for some databases – including the one with 7 days to live (what should be displayed [3], what is actually displayed [4]).
Even in perfect circumstances, 7 days is just too aggressive.
[1] https://i.imgur.com/FDF6Gu4.png
[2] https://www.heroku.com/pricing#data-services
[3] https://i.imgur.com/tAmmNx5.png
[4] https://i.imgur.com/DUdXB7P.png