That was like what, 7 years ago? Do you think this has changed now about Mongo since then?
I had a similar experience around the same time - still don't feel like giving that widowmaker another chance.
The best predictor of future behavior is history.
Much like the startup CEO I mentioned, Mongos developers don't really seem to care much about here and now.
Whats your opinion on postgres vs nosql like cassandra and aerospike, fundamentally is there any reason that postgres can't scale as well as nosql? If I store key value in postgres and add read replica to scale read and partition to scale write will I not be able to keep up with other nosql solutions? If so what are the reasons?
I would say that by the time you (potentially) have those kinds of problems, you'll most likely have the resources to deal with them.
It's sort of a nice class of problems to have, and a lousy heuristic for choosing solutions before you know what exactly you're dealing with.
Worked for a valley startup back in 2013 that picked Mongo as primary data store because the CEO liked the simplicity and was too busy with the future to learn anything more complicated.
I only implemented a couple of features before I got out of that mess. But from my experience, compared to dozens of SQL and NoSQL databases I've worked with; it was definitely the worst option. We spent way too much time dealing with Mongo-specific issues and limitations.