Old timers will recall when using mmap was a prominently promoted selling point for the “no sql” dbms.
reminds me of how industries typically start out dominated by vertically integrated companies, move to specialized horizontal companies, then generally move back to vertical integration due to efficiency. Car industry started this way with Ford, went away from it, and now Tesla is doing it again. Lots of other examples in other industries
You almost always want somewhere in the middle, but it’s often much easier to move back after a large jump in one direction than to push towards the middle.
And there was a very well known cartoon video discussion about it with “web scale” and “just write to dev null” and other classics that became memes :)
Admittedly I live in a world where big distributed transactions are a given and work fine and sql speeds us up not slows us down. I’m guessing sql and acid scaled after all?
Yes and no. Distributed transactions and two-phase commit have been superseded by things like Paxos and Raft, with a variety of consistency models, so the implementation is drastically different.
There are some applications that require high throughput (usually write) but can be fine with read consistency.
Couple of examples - consumer facing comment systems where other users are OK to miss your comment by 30 seconds - timeseries logging where you are usually reading infrequently but writing very much in a denormalized format so joins aren't as critical
For general CRUD, ACID is important though.