Show HN: PumpkinDB, an event sourcing database engine
It's a lower-level "database engine" that allows you to build different types of higher level databases based on a very simple foundation:<p>1) BTree-based K/V engine (which gives you an ability to iterate over lexicographically sorted keys) 
2) Strong immutability guarantees (data can not be overwritten) 
3) ACID transactions 
4) Server-side executable imperative language that gives you a control over querying costs<p>In a sense, it's as much of a database constructor as different MUMPS systems (GT.M, for example: <a href="https://en.wikipedia.org/wiki/GT.M" rel="nofollow">https://en.wikipedia.org/wiki/GT.M</a>)<p>PumpkinDB also aims to provide a good set of standard primitives that help building more sophisticated databases, ranging from hashing to JSON support, and more to come.