Bye Bye Mongo, Hello Postgres

Specific technology choices aside, this was an incredible write-up of their migration process: thorough, organized, readable prose about a technical topic. It is helpful to read how other teams handle these types of processes in real production systems. Perhaps most refreshing is the description of choices made for the various infrastructure pieces, because it is reasonable and real-world. Blog posts so often describe building a system from scratch where all latest-and-greatest software can be used at each layer…

The takeway IMO is that the reason their transition was so seamless is because they took the time to do it 'the right way' - that is: set up the new system in parallel, duplicating the reads and writes, and verifying that things looked good every step of the way. That gives you not only a long window to test and validate, but also the option to rollback if things suddenly don't look so good with the new system. It…