PumpkinDB is an immutable ordered key-value database engine, featuring:
- ACID transactions
- Persistent storage
- An embedded programming language (PumpkinScript)
- Binary keys and values (allows any encoding to be used: JSON, XML, Protobuf, Cap'n Proto, etc.)
- Standalone and embedded scenarios
Simply put, the data replaced is data deleted and is therefore, an unsafe way to manage data. Bugs, misunderstanding, changing scope and requirements and other factors might influence what data (and especially past data) means and how can it be used.
By guaranteeing the immutability of key's value once it is set, PumpkinDB forces its users to think of their data through a temporal perspective.
This approach is highly beneficial for implementing event sourcing and similar types of architectures.
What is PumpkinDB?
PumpkinDB is essentially a database programming environment, largely inspired by core ideas behind MUMPS. Instead of M, it has a Forth-inspired stack-based language, PumpkinScript. Instead of hierarchical keys, it has a flat key namespace and doesn't allow overriding values once they are set. Core motivation for immutability was that with the cost of storage declining, erasing data is effectively a strategical mistake.
While not intended for general purpose programming, its main objective is to facilitate building specialized application-specific and generic databases with a particular focus on immutability and processing data as close to storage as possible, incurring as little communication penalty as possible.
Applications communicate with PumpkinDB by sending small PumpkinScript programs over a network interface (or API when using PumpkinDB as an embedded solution).
PumpkinDB offers a wide array of primitives for concurrency, storage, journalling, indexing and other common building blocks.
Why is it a database engine?
The core ideas behind PumpkinDB stem from the so called lazy event sourcing approach which is based on storing and indexing events while delaying domain binding for as long as possible. That said, the intention of this database is to be a building block for different kinds of architectures, be it classic event sourcing (using it as an event store), lazy event sourcing (using indices) or anything else. It's also possible to implement different approaches within a single database for different parts of the domain.
Instead of devising custom protocols for talking to PumpkinDB, the protocol of communication has become a pipeline to a script executor. This offers us enormous extension and flexibility capabilities.
While an external application can talk to PumpkinDB over a network connection, PumpkinDB's engine itself is embeddable and can be used directly. Currenly, it is available for Rust applications only, but this may one day extend to all languages that can interface with C.