Found two sneaky costs in @gumroad's AWS bill:
1. Since Rails 8.1, a worker in every preview app was stuck in an OOM-kill loop, burning CPU credits
2. Our Elasticsearch client logged every request and response body: half our log volume
With cleanup: ~$1.4k/mo, ~$17k/yr saved
We recently migrated ~1B email analytics records at @gumroad from MongoDB to DynamoDB. Zero downtime.
Query time: 861ms → 7ms
Cost: $1,378 → $207/mo (~$14k/yr saved)
The trick: single-table design with precomputed counters. A stats page is one read, not a count per email.