I would argue this question is not really related, but we use PrestoDB (the technology AWS Athena is built using), and it is particularly great for when data becomes too large to fit in a "regular" database. PrestoDB and Apache Impala are the two major open-source surprisingly-fast-distributed-SQL-query-planning-engines. If you pair either of them with a columnar data storage format like Parquet or ORC, you can make analytical workloads work on inconveniently-sized data. AWS Athena abstracts the cluster management for you and runs PrestoDB on spare EC2 instances under the hood.