[hampereddustbin]

I'd say the part

>versus the AWS shop where the Dynamo guy knew the innards of the database by chapter and verse)

Definitely has a big impact on it. The angle at which people approach these databases is completely different from my experience. MongoDB is advertised with words like "developer friendly" and "just works", so people tend to just start it up and not read too much into it.

On the other hand DynamoDB was described to us as "monkey's paw", "Carefully read before use", "know what you're doing". And so we combed through first all the pitfall blogs, then AWS documentation, and then carefully tried out all the features we wanted to use and tested the scenarios separately.

[AtlasBarfed]

How does he know how a black box database works inside and out?

That's an issue with dynamo. Sure you can memorize the API, but you have no idea what is actually going on and aws support will NEVER tell you what is happening.

Postgres, Cassandra, etc are source available and yes I have multiple times looked at Cassandra code to figure out what it was doing.

[hot_gril]

DBs in general have a lot of unavoidable complexity swept under the rug. Like, I don't think most people realize Postgres and MySQL don't do full ACID transactions by default. But it's even worse how special DBs made for huge shardable data like Mongo market themselves as beginner-friendly.

Also the SQL timestamp vs timestamptz thing is just silly and avoidable. I want to know who I complain to for that.