TLDR: author forgot to create indexes in cloud-based MySQL database and paid too much for the queries which were run as full-table scans. Interestingly enough,

TLDR: author forgot to create indexes in cloud-based MySQL database and paid too much for the queries which were run as full-table scans. Interestingly enough, some DBs (like Cassandra) would refuse scan-type queries unless specifically asked to. I wonder if cloud-based DBs which charge per row inspected could have such mode... Though of course it's their incentive not to.