Deploy Citus

Deploy and Host Citus on Railway

Citus is an open-source PostgreSQL extension that transforms PostgreSQL into a distributed database. It enables horizontal scaling through sharding, parallel query execution, and distributed tables while preserving the familiar PostgreSQL ecosystem, SQL syntax, drivers, and tooling.

About Hosting Citus

Hosting Citus on Railway lets you run a distributed PostgreSQL cluster without manually provisioning multiple servers.

This template uses a coordinator and three worker nodes. The coordinator acts as the main PostgreSQL entry point and manages distributed metadata, while the worker nodes store distributed table shards and execute queries in parallel.

Each node uses persistent storage, and internal cluster communication runs through Railway's private network. Only the coordinator needs to be exposed to external PostgreSQL clients.

This architecture is suitable for applications that have outgrown a single PostgreSQL instance and need horizontal scaling while retaining PostgreSQL compatibility.

Common Use Cases

• Scale PostgreSQL horizontally across multiple nodes
• Shard large tables across distributed workers
• Build scalable multi-tenant SaaS applications
• Run parallel analytical queries on PostgreSQL data
• Handle large event, telemetry, and time-series datasets
• Distribute high-volume application workloads
• Scale reporting and aggregation queries
• Reduce pressure on a single PostgreSQL server
• Build distributed data platforms using familiar PostgreSQL tooling

Dependencies for Citus Hosting

• Citus coordinator node
• Three Citus worker nodes
• Persistent storage for each PostgreSQL node
• Railway private networking between coordinator and workers
• PostgreSQL-compatible clients and drivers

Citus Architecture

This template uses a four-node Citus cluster:

External Applications
        │
        ▼
Citus Coordinator
        │
        │ Railway Private Network
        │
   ┌────┼────┐
   ▼    ▼    ▼
Worker Worker Worker
  1      2      3
   │      │      │
Volume Volume Volume

The coordinator is responsible for:

• Accepting PostgreSQL client connections
• Managing distributed table metadata
• Planning distributed queries
• Routing queries to the appropriate worker nodes
• Coordinating parallel query execution

The workers are responsible for:

• Storing distributed table shards
• Executing queries against local shards
• Returning partial results to the coordinator
• Providing horizontal storage and compute capacity

Each node uses its own persistent storage because distributed table data is physically stored across the worker nodes.

Citus vs Similar Platforms

Citus is a strong choice when PostgreSQL compatibility is important but a single PostgreSQL server is no longer sufficient.

PostgreSQL remains simpler for smaller workloads that fit comfortably on one server. CockroachDB provides a distributed SQL architecture with strong resilience features, but it is not a PostgreSQL extension and differs internally from PostgreSQL. ClickHouse is highly optimized for analytical workloads, but is not designed as a drop-in PostgreSQL replacement for transactional applications.

Why Use Citus?

Citus allows applications to scale PostgreSQL without abandoning the PostgreSQL ecosystem.

Instead of moving to an entirely different distributed database, Citus extends PostgreSQL with distributed tables, shard placement, and parallel query execution.

This makes it especially suitable for systems that already depend on PostgreSQL-compatible drivers, ORMs, extensions, and operational tooling.

Citus is commonly useful when data can be distributed using a natural key such as:

• Tenant ID
• Customer ID
• Account ID
• Device ID
• Organization ID

Choosing the right distribution column allows related data to remain colocated on the same worker, reducing cross-node communication and improving distributed query performance.

Horizontal Scaling

Distributed tables are divided into shards and distributed across worker nodes.

As the dataset grows, additional workers can be added to increase:

• Storage capacity
• Query throughput
• Parallel processing capacity
• Aggregate compute resources

Shard placement can then be rebalanced across the available workers.

This scale-out architecture allows workloads to grow beyond the practical limits of a single PostgreSQL instance.

Why Deploy Citus on Railway?

Railway is a singular platform to deploy your infrastructure stack. Railway will host your infrastructure so you don't have to deal with configuration, while allowing you to vertically and horizontally scale it.

By deploying Citus on Railway, you are one step closer to supporting a complete full-stack application with minimal burden. Host your servers, databases, AI agents, and more on Railway.