VarveDB

What it is

VarveDB is a high-performance, embedded, append-only event store for Rust. It is built on LMDB (via heed) and rkyv, targeting event sourcing and audit logs with predictable performance and zero-copy reads.

Core capabilities

• Zero-copy access via rkyv (no deserialization on reads)
• High-throughput batch writes (1M+ events/sec)
• Embedded, in-process architecture with no external services
• Strongly typed events enforced by Rust
• ACID transactions and crash safety through LMDB
• Stream organization with global ordering across streams
• Optional async notifications for write watchers

Architecture highlights

VarveDB stores events in three LMDB-backed components:

• Global append-only log ordered by global sequence
• Stream index for efficient per-stream lookups
• Stream metadata tracking stream sequence heads

This layout keeps writes sequential while enabling fast per-stream and global iteration.

Performance snapshot

Benchmarks on a MacBook Pro M2 + NVMe show:

• Batch write: ~1.02M events/sec (≈978 ns/event)
• Sequential read: ~2.28M events/sec (≈438 ns/event)
• Stream iteration: ~2.92M events/sec (≈342 ns/event)

Status

Under active development; APIs and storage formats may evolve before 1.0.