You know, this seems like a perfect example of what a "simple" approach to scaling is: realizing that CI is the most likely thing to cause issues in the future due to how popular it is and then splitting the database along that particular boundary, due to the actual need that has arisen.

You don't always need to experiment with bleeding edge tech or very complicated multi-leader clusters (though those also have their own use cases at a certain scale), sometimes just splitting the whole thing, especially when using something as solid as PostgreSQL, is enough!

While I agree that this is a wonderfully simple case the main problem is that it isn't always that easy. As long as you get get away slicing tables into different "shards" and aren't to join-heavy it isn't too baf. However it still adds complexity to the application code that is a constant maintenance cost. And eventually if you keep scaling you will get to the point where you need to shard a single table, and that is very painful. Both in the risk and difficulty of the conversion and further ongoing development costs.

I do dream of the day when distributed databases are the "default" for new projects. Likely running just a single instance at the beginning. But then you have a seamless path forward when (and if) you need it. Even at medium size three small nodes will be easy to manage and give easy HA and allow you to do version updates safely and with no downtime.

I don't think we are there yet, but there are a few contenders in the running but Postgres is tough competition. Its years of stability and predictability give it huge points even if it has the downsides of a centralized system. But I think the turning point is steadily approaching.

Which databases are the main contenders, that you were referring to?

But there are also https://www.cockroachlabs.com/product/, https://github.com/pingcap/tidb and https://ydb.tech/ which each has promise.

There is definitely lots of progress to make in this space. From what I have seen they are all significantly slower on a single node and are not as battle-hardened. But I think with time we will have a few really nice options to pick from.