[jimbokun]

We decided to go for a Big Rewrite for a completely different reason. The initial license for the proprietary NoSQL database we had negotiated was about to expire, and the company was going to charge us an order of magnitude more to renew.

So we immediately set out redesigning our system to use other, fully open source technologies. Also gave us an opportunity to reconsider architecture decisions that had not scaled well. In our case, moving from a monolith to microservices has had major benefits. Maybe the biggest being able to quickly see which microservice is the bottleneck and needs to be scaled up to handle the load. With the monolith, if it got slow, it was very difficult to figure out which part of the workload was making it slow.