Why choose BigQuery for Billing Setup & Why not Cloud SQL or similar
Ah, I’m glad you’ve asked! There are two key reasons:
1) Cloud SQL is something you provision and pay for it to be able to handle a particular capacity, regardless of whether you are using it. The minimum cost to keep a Cloud SQL instance running is significant, even if you never query it. On the other hand, BigQuery will accept the billing data it gets sent and then basically "go to sleep" waiting for you to come and query it. BigQuery charges a (relatively) tiny amount to hold on to that data for you–but even that, only after you’ve gone past the free tier (of 10GB). Then, when you do query it, you can have it process/reprocess up to 1TB of data before you go past its free tier for that, too. So you are unlikely to pay anything for this, at all!
2) Google only supports billing export to BigQuery, and not Cloud SQL. So that’s the only way to do it automatically. I mean, I guess you could export it to a file in Cloud Storage and then load it up into a Cloud SQL instance, if you want to, but… ¯_(ツ)_/¯
I hope this helps!