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Evaluating CouchDB as a database for a NOSTR relay

Introduction

NOSTR (Notes and Other Stuff Transmitted by Relays) is a decentralized messaging protocol that relies on relays to distribute user-generated content. Since relays function as the backbone of NOSTR’s decentralized nature, the choice of database significantly impacts performance, scalability, and data propagation.

Apache CouchDB, a document-based NoSQL database, offers a compelling set of features for a NOSTR relay, including built-in multi-master replication, a web-native HTTP API, and schema-free JSON storage. These built-in features align well with the needs of a NOSTR relay, particularly in terms of distributed data synchronization and ease of development.

This article provides a detailed analysis of CouchDB’s suitability for NOSTR relays, discussing both its advantages and challenges. By the end, readers will have a clear understanding of whether CouchDB is a good fit for their specific relay deployment needs.

Understanding CouchDB’s Core Features

CouchDB is designed for distributed, scalable applications with a focus on reliability and simplicity. The key architectural features that make it an interesting candidate for a NOSTR relay include:

  • Document-Based NoSQL Storage: CouchDB stores data as JSON documents, making it inherently compatible with NOSTR’s JSON-based messages.
  • Multi-Master Replication: One of CouchDB’s strongest features, allowing multiple nodes to sync data seamlessly without a centralized authority.
  • Conflict Resolution Mechanisms: CouchDB handles conflicts using a deterministic approach, providing mechanisms to reconcile conflicting updates across distributed nodes.
  • Web-Native HTTP API: CouchDB provides a RESTful interface for direct database interactions, eliminating the need for complex backend logic.
  • Deterministic Revision Hashes: Each document save operation generates a unique but deterministic revision hash. This ensures that identical documents stored across different relays will produce the same hash, facilitating consistency checks and data integrity within NOSTR’s decentralized framework.
  • Database-Per-User Model: CouchDB supports a unique database-per-user approach, allowing each user to have an isolated data store. This aligns with NOSTR’s decentralized nature by providing personal data silos while enabling seamless replication across nodes.

These features provide a strong foundation for building distributed applications. But how well do they align with the requirements of a NOSTR relay?

The Pros of Using CouchDB for a NOSTR Relay

Seamless Replication Across Geographical Locations

One of the biggest challenges in running a decentralized relay network is keeping data synchronized across multiple locations. CouchDB’s multi-master replication makes this effortless:

  • Relays can sync with each other automatically, ensuring data consistency without requiring external tools.
  • Operators can deploy geographically distributed relay clusters that replicate data in near real-time.
  • The eventual consistency model aligns well with the decentralized nature of NOSTR.

Web-Native API Simplifies Relay Development

CouchDB’s built-in HTTP API significantly reduces development overhead:

  • Developers can interact with the database directly using simple HTTP requests (GET, POST, PUT, DELETE).
  • CRUD operations and indexing are handled through RESTful endpoints, eliminating the need for additional backend API layers.
  • A NOSTR relay can be built with minimal infrastructure, as CouchDB natively handles document storage and retrieval.
  • The live _changes feed offers multiple possibilities of handling ongoing push updates to users.

Example API call to retrieve a NOSTR event directly to a CouchDB instance:

curl -X GET http://localhost:5984/nostr_events/event_id

Horizontal Scalability & Fault Tolerance

  • CouchDB allows new nodes to be added easily without requiring major modifications to the relay.
  • Fault tolerance is built-in: if one node goes down, other nodes with replicated data can continue serving requests.
  • The eventual consistency model ensures that all nodes converge to the same state over time, making it resilient to temporary network failures.

Schema-Free JSON Storage

NOSTR events are stored as JSON, making CouchDB a natural fit:

  • No rigid schema means relays can evolve without requiring complex database migrations.
  • Storing different event types (text notes, metadata updates, etc.) is seamless.
  • Indexing can be customized using CouchDB’s MapReduce views to optimize query performance.

Deterministic Revision Hashes Aid Decentralization

CouchDB’s revision hash system adds another key advantage for a NOSTR relay:

  • Since revision hashes are deterministic, identical documents stored in different relays will produce the same hash.
  • This enables relays to verify whether data has changed without requiring extra metadata or conflict resolution logic.
  • It strengthens NOSTR’s decentralized architecture by making data verification trustless and self-contained.

Query Performance and Indexed Views

One of the main concerns about NoSQL databases is query performance. However, CouchDB mitigates this through precomputed MapReduce views:

  • Once a view index is built, queries run against it are extremely fast.
  • This allows NOSTR relays to efficiently retrieve specific events, such as all messages from a given user or those matching a certain tag.
  • Unlike traditional databases that execute queries dynamically, CouchDB’s approach favors performance by keeping indexes up to date with minimal overhead.
  • Properly designed list indexes ensure that even large datasets can be queried efficiently, reducing database load.

The Cons and Challenges of Using CouchDB for a NOSTR Relay

Performance Considerations

While CouchDB excels in availability and replication, it is not optimized for high write throughput:

  • High-volume NOSTR relays handling thousands of messages per second may experience performance bottlenecks.
  • CouchDB’s append-only storage engine ensures data durability but can slow down under heavy concurrent writes.
  • Write performance can be improved using sharding strategies or by offloading high-frequency events to an external caching layer (e.g., Redis).

Conflict Resolution Complexity

Multi-master replication can introduce conflict resolution challenges:

  • When two nodes receive different updates to the same document, CouchDB must resolve conflicts based on a deterministic algorithm.
  • Handling event consistency in a NOSTR relay may require additional application logic to ensure correct ordering of messages.

Security Concerns with the HTTP API

CouchDB’s open API can be an attack vector if not properly secured:

  • By default, CouchDB exposes a RESTful API that allows read and write operations.
  • Without proper authentication and access control, a relay could be susceptible to unauthorized data manipulation.
  • Security best practices include:
    • Using reverse proxies (e.g., Caddy, Nginx) to restrict access. Never expose the root CouchDB URL on a public instance.
    • Enabling CouchDB’s built-in authentication mechanisms.
    • Applying CORS policies to control who can interact with the database.

Conclusion & Final Thoughts

CouchDB presents a strong case for use in NOSTR relays where data replication and ease of integration are key priorities. Its multi-master replication ensures seamless data distribution, while the web-native HTTP API simplifies relay development. The deterministic revision hash system further strengthens its viability by ensuring consistent document identification across decentralized nodes.

However, performance limitations, conflict resolution complexities, and security concerns must be carefully considered. High-frequency relays with massive write loads may find CouchDB’s performance insufficient without additional optimizations.

For developers considering CouchDB, testing performance at scale and implementing proper security measures are critical. In the right scenarios, CouchDB can be a powerful and flexible backend for a decentralized NOSTR relay.

What's next?

We have started development of a proof-of-concept NodeJS+CouchDB relay server to showcase and start doing real-life testing. Connect with us on our NOSTR profile and follow updates on the public git repository.