>Most people assume mutable state and incremental updates when building data systems. This is in fact the approach that almost all databases take. These are the assumptions I challenged.
it isn't assumptions. It is requirements for some systems. You drop requirements - you get a breathing room and can build a different system.
Mutability and incremental updates are never requirements. Requirements have to do with performance and resource usage: X amount of space, Y amount of memory, Z amount of latency, etc.
Mutability and incremental updates are approaches. I showed a different approach with immutability at the core which leads to a system with some amazing properties.
I hope that examples like this and git make more people see the value of immutability. In the context of functional programming the same concept is called purity.
it isn't assumptions. It is requirements for some systems. You drop requirements - you get a breathing room and can build a different system.