I thought GemFire was directly derived from GemStone, via numerous acquisitions. If GemStone has a different transaction model I don't know it.
The point is, no distributed database with a naive two-phase lock is truly transactional.
The point is, no distributed database with a naive two-phase lock is truly transactional.
I have no idea how you can draw similarities between the two. One of them is basically a Smalltalk VM with automatic object persistence. The other is some kind of real-time Java-based distributed key/value data platform.
The GemStone transaction docs describe a scheme that would work properly on a single machine, but don't discuss anything about distributed coordination across servers or failure modes. The installation instructions don't discuss setting up a cluster. The marketing docs discuss using thousands of VMs (clients) and scaling the dataset to "hundreds of gigabytes" based on disk storage instead of memory which is not what I would expect from a distributed system. Various benchmarks and user comments refer to using a single server for GemStone.
I will update the post to clarify that we are discussing distributed document databases only. It's easy to do anything you want on a single machine.