Introduction

Kronotop is a distributed, transactional document database built on FoundationDB.

It gives every AI agent, tenant, or app its own logical database, called a namespace, and runs many namespaces on one cluster. A namespace is a keyspace prefix, so creating one is free, and isolation comes from the prefix instead of application code. One transaction commits across any number of namespaces.

Inside a namespace there are two data models behind one RESP interface: Bucket, a document model with secondary indexes and vector search, and ZMap, an ordered key-value model. Both share the same transaction. Document bodies are stored on a local disk by Volume, a segment-based storage engine with primary-standby replication.

Namespaces

Namespaces are lightweight logical databases built on FoundationDB’s directory layer, with hierarchical, dot-separated paths. Each namespace has its own keyspace; buckets, indexes, and ZMap keys in one namespace are invisible to another. Creating one is cheap, so a single cluster can hold a namespace per tenant, per app, or per agent.

Data Models

Bucket stores BSON documents and provides a query language (BQL) with comparison, logical, and array operators. Buckets support single-field, compound, and vector indexes. Vector indexes are powered by JVector, use HNSW with automatic Product Quantization, and support cosine, euclidean, and dot_productdistance functions. Results are ranked by similarity first, then filtered with BQL predicates (post-filtering).

ZMap is a RESP-compatible proxy over FoundationDB’s ordered key-value API. Keys and values are opaque byte sequences. Keys are stored in lexicographic order. ZMap provides typed numeric operations (int64, float64, decimal128), conflict-free atomic mutations through FoundationDB’s atomic primitives, and range operations over the ordered key space.

Transactions

Transactions are strictly serializable, inherited from FoundationDB. Each command runs in auto-commit mode by default. BEGIN and COMMIT group commands into a single atomic unit. A single transaction can atomically span multiple namespaces. Snapshot reads are available for read-heavy workloads where strict serializability is not required.

Wire Protocol

Kronotop speaks RESP2 and RESP3 and works with existing RESP-compatible clients. kronotop-cli or valkey-cli can connect directly.

Getting Started

The Quickstart starts a minimal cluster with Docker Compose and walks through inserting and querying a document.