FalkorDB is a graph database implemented as a Redis module, written in Rust. It supports the Cypher query language and uses sparse matrices and GraphBLAS/LAGraph for efficient graph operations. The system features MVCC for concurrency control, a batch-oriented query execution engine, and pluggable indexing (including native FalkorDB index for range, full-text, and vector search). Key architectural layers include the Redis module interface, query parser/planner, runtime operators, and storage backend. The codebase demonstrates strong modularity and includes several reusable patterns such as copy-on-write for MVCC, a storage backend seam, thread-local string interning, batched result emission, and a pipeline of query optimization passes.
SpacetimeDB is a real-time database system that enables developers to upload application logic directly into the database as modules, eliminating the need for traditional backend servers. Clients connect directly to the database using language-specific SDKs (Rust, C#, TypeScript, C++, Unreal) and receive real-time updates when data changes. The system features a Rust-based core server, WebSocket-based synchronization, ACID transactions, and a code generation system that creates language bindings from module definitions. Notable features include schema evolution capabilities, scheduled procedures, and row-level security. The entire backend of MMORPG BitCraft Online runs as a single SpacetimeDB module, demonstrating its capacity for complex, high-performance applications.