eventstore
An Elixir event store with PostgreSQL persistence, supporting clustering, subscriptions, and ACID compliance.
What is eventstore?
EventStore is an event sourcing library implemented in Elixir that uses PostgreSQL for persistent storage. It provides a way to append, read, and subscribe to events in streams, enabling developers to build event-driven applications with strong data integrity guarantees. It solves the problem of reliably storing and retrieving event sequences in a scalable, ACID-compliant manner.
Elixir developers building event-driven systems, microservices, or applications following CQRS and event sourcing patterns who need a reliable, PostgreSQL-backed event store.
Developers choose EventStore for its simplicity, reliance on PostgreSQL's proven reliability, and native Elixir integration. It offers clustering support, persistent subscriptions, and comprehensive tooling for production use, making it a robust open-source alternative to commercial event stores.
Overview
Event store using PostgreSQL for persistence
Use Cases
Best For
- Building event-driven microservices in Elixir
- Implementing CQRS and event sourcing patterns with PostgreSQL
- Creating audit logs or activity feeds that require strong consistency
- Developing systems that need real-time event subscriptions
- Scaling event storage across a cluster of nodes
- Applications requiring ACID-compliant event persistence
Not Ideal For
- Polyglot microservices architectures using multiple programming languages
- Systems requiring ultra-low latency event ingestion (e.g., high-frequency trading)
- Environments without PostgreSQL or unwilling to manage database infrastructure
- Simple event logging or messaging where full event sourcing is unnecessary overhead
Pros & Cons
Pros
Builds on PostgreSQL's ACID compliance and transactional guarantees, ensuring data integrity and correctness for event storage, as highlighted in the production use section.
Supports both transient and persistent subscriptions with acknowledgment mechanisms, enabling real-time event processing and reliable delivery, detailed in the Subscriptions guide.
Includes performance benchmarks to measure throughput for concurrent reads, writes, and subscriptions, helping users assess the impact of changes, as shown in the benchmarking output examples.
Can run on a cluster of nodes for scalability and fault tolerance, with a dedicated guide for cluster setup, making it suitable for distributed applications.
Cons
Tightly coupled to PostgreSQL as the sole storage engine, limiting flexibility for teams using other databases or cloud-native storage solutions.
Implemented in Elixir and reliant on the BEAM VM, making it unsuitable for non-Elixir projects without complex interop or bridging layers.
Default JSON serialization can slow performance; optimal throughput requires Erlang's external term format, which ties data to the Erlang ecosystem and complicates cross-platform use.
Frequently Asked Questions
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