firestore: Storage charges do not go down after deleting data

[kyle_int]

Hello,

I deleted a large amount of data from Firestore in our test project 5 days ago.

But the Cloud Firestore Storage cost in the billing report does not decrease.

Even though I deleted about 2 million documents, the cost increased instead of decreasing.

I also saw an article that said it could be because Firestore's garbage collection is delayed, but it's strange that it hasn't changed even after 5 days.

Did I miss something?

Thanks for your time and attention.

[mcbsalceda]

Hi @kyle_int,

Welcome to Google Cloud Community!

It looks like the issue you're encountering could be related to the write and delete charges in Firestore. According to Firebase pricing, each write and delete operation incurs a cost, and that includes both document writes (like updates or creations) and deletes. So even though you deleted a large number of documents, there are a few things that might explain why your costs aren't going down:

• Costs of Deletions. When you delete documents, Firestore charges for both reads (to fetch the documents before deleting) and the delete operation itself. The number of deletes you perform could result in significant costs, especially with 2 million documents. So while you're deleting, you're also incurring delete costs.
• New Writes or Updates. If you've added new data or updated documents after the deletions, those actions count as writes and would increase your costs. Every set() or update() operation is considered a write and incurs a charge. So if there was any new data added or updates to existing data, this could be what's causing your costs to go up rather than down.
• Delayed Reclaim of Storage. Firestore’s garbage collection doesn’t immediately free up space after deletions. The storage cost reduction can take some time, even though the deletes are recorded.

If you deleted the documents using the Firebase CLI, keep in mind that those operations incur both read and delete charges. So, if you ran a large delete operation, this could explain why you're still seeing high costs despite deleting the documents. If you're not seeing the expected cost reduction after a reasonable delay, it might be worth reviewing how many writes or deletes were performed, as those operations can quickly add up in cost. You might also want to check out the Understand Cloud Firestore billing documentation to get a better understanding of how Firestore billing works and what factors contribute to your costs.

Hope this helps!