rigaspapas

Update: The cost is a good point. It wasn't that high. We actually updated the article to reflect this. It was two engineers, working full-time on it, for three weeks.

A few minutes of downtime wouldn't be that bad, but it would harm the company's prestige. Unlike AWS and Netflix, we are not based on massive consumption, but on a few customers. Losing one good customer can make a difference. We believe it worth the investment of time.

You are right. AWS DMS was our very first choice to try out. It is very easy to use, deployed within your VPC and most of the problems we mention in the article are already solved. Unfortunately, we experienced errors during our tests and the logging mechanisms were not quite helpful, so we failed to find out the problem and make it work.

That's a good point. We mention latency as "replication lag" and we have devoted a paragraph to the drift that comes as the result of this latency. In our case, we measured the latency to be <1s, and it was totally acceptable. As for the performance, triggers can become a problem with enough write traffic. In a different use case, Bucardo would be eliminated from a potential solution due to this.

We didn't mean to be arrogant with the "done right" statement. In the background story we explain how we performed the same migration once again in the past, and we end up with data loss. So this was the time that actually "did it right". Many tutorials on the Internet that describe a similar process have flows that also lead to data loss.

AWS can upgrade your database automatically, but with some downtime. AWS also provides DMS for migrations, which didn't work well in our case. So it was rather a simple problem at first, which turned to be a very complex one in the end.

Exactly. With so many people out there advertising themselves as "software engineers" but being "coders", companies fail to produce maintainable code without a bunch of strict rules. Coding manifestos are a must these days, otherwise you end up with a codebase that looks like the Tower of Babel.

This is what happens when you don't pin your dependencies, right?