StateVec targets core business transactions. Hash-linked history makes execution results comparable across replicas, and Verify mode compares them before commit. The framework manages data models and recovery snapshots, so business teams can focus on rules, and downstream queries and notifications can be added independently.
| Dimension | StateVecA general-purpose engine for consistent core business state | SpacetimeDBReal-time application backend and database ↗ | Aeron ClusterLow-latency, highly available cluster framework ↗ |
|---|---|---|---|
| Positioning | General-purpose core business engine: consistent state, cluster availability, a traceable transaction history and extensible downstream views. | Database and application service combined: real-time logic, relational tables and client state synchronization for games and other applications. | Low-latency replicated-state-machine framework: highly available stateful services, including financial trading. |
| What developers define | Records, commands, events and deterministic plugin business logic. | Module tables, transaction functions called reducers, and access rules. Clients invoke reducers and subscribe to data. Modules support Rust, C#, C++ and TypeScript. | A message protocol, a deterministic business service (ClusteredService) and business state. Developers implement snapshot encoding and startup restoration and configure Archive log storage. |
| What the framework provides | Typed data definitions and request validation; transactions, two execution modes and hash-linked history; batch submission, client recovery and recovery snapshots; read-side extension interfaces. Online upgrades are in development. | Table schemas and migration, atomic reducer transactions, commit-log/snapshot recovery, queries, subscriptions and client SDKs. Cloud provides clustered replication. | Raft ordering and replication, failover, reliable timers, log archival and replay. Snapshot interfaces are provided; business code encodes and restores its state. |
| Replication ① | Command replication and deterministic re-execution; many mutations need not be replicated row by row. | Row-change replication; large mutation sets may increase read/write amplification. | Message replication and deterministic re-execution. |
| Explicit data definitions ② | Provided | Provided | Not described |
| Automatic record revisions ③ | Provided | Not described | Not described |
| Business invariants | In development ④ | Not described | Not described |
| Execution re-verification ⑤ | Provided (Verify mode) | Not described | Not described |
| Pluggable downstream extensions ⑥ | Framework provided; learner integration in development | Not described | Not described |
Provided: a built-in mechanism exists. Not described: the cited public material describes no corresponding built-in mechanism; applications may implement their own.
① Linearizability covers one StateVec replicated state machine. Asynchronous projection reads follow a separate consistency model. Verify mode adds execution verification. Amplification refers to change logs and recovery I/O; query costs require separate measurement. Cost comparisons should also account for compression, checkpoints and replica computation. References appear below.
② Data definitions describe the business state the framework manages. Message formats and data-format versions are separate concepts.
③ A revision is the version number of one individual record. Schema and plugin versions are tracked separately.
④ In development: business-invariant checks during execution and snapshot loading.
⑤ The hash chain binds the previous hash, transaction sequence, input identifier and result digest. Verify mode recomputes results and chain hashes on the execution path; this is not a background scan of all state. Performance mode computes a real chain, but nothing yet samples and compares chain hashes across replicas in the background. A hash chain does not prove that business logic is correct and cannot detect an error that every replica produces identically.
⑥ Downstream extensions are independent, pluggable view builders. Adding subscriptions or updating a module is a different capability.
References
The comparison is based on official documentation and does not imply third-party endorsement. Original reference review: 2026-09-16; additional SpacetimeDB review: 2026-09-18.
- StateVec: cluster architecture, plugin contract, engineering notes and design stories.
- SpacetimeDB: Key Architecture, Transactions and Atomicity, Commitlog, Functions, Procedures and Cloud architecture (2026-09-03). These sources describe transactions, recovery, return values, subscriptions and Cloud replication. We have not reviewed the closed-source cluster implementation.
- Aeron Cluster: Overview, Basic Sample, Efficient Business Logic and Cluster Tutorial. Raft replication, deterministic business responsibilities, snapshot and replay interfaces.