A client recently inquired about the costs of running Cassandra vs a traditional RDBMS like Postgres or Mysql, in the cloud.
They are releasing a b2b product similar to Slack, Trello, etc which will have a free tier. And they're concerned about the costs of running it on Cassandra, and whether it may be too expensive if it gets popular. They have a write heavy workload, where data is being received 24/7, analyzed and the results written to Cassandra. A few times a day, users will view the results of the analysis, which will be the read portion of the system. Its my understanding that it may cost slightly, e.g 10-15% more to run this system on Cassandra vs an RDBMS, because it needs more nodes, and higher tier of AWS / GCE instances to run. Can anyone who has experience scaling Cassandra share their insights? Costs, metrics (e.g users, requests per second), etc would be really helpful!
