EventStore

CQRS Event Store implemented in Elixir. Uses PostgreSQL as the underlying storage. Requires version 9.5 or newer.

License is MIT.

Getting started

EventStore is available in Hex, the package can be installed as follows:

1. Add eventstore to your list of dependencies in mix.exs:

   def deps do

    [{:eventstore, "~> 0.0.1"}]

   end

2. Ensure eventstore is started before your application:

   def application do

    [applications: [:eventstore]]

   end

3. Add an eventstore config entry containing the PostgreSQL connection details to each environment's mix config file (e.g. config/dev.exs).

```elixir
config :eventstore, EventStore.Storage,
  username: "postgres",
  password: "postgres",
  database: "eventstore_dev",
  hostname: "localhost"
```

1. Create the EventStore database using the mix task

```
mix event_store.create
```

This will create the database and tables.

Sample usage

# start the Storage process
{:ok, store} = EventStore.Storage.start_link

Writing to a Stream

# create a unique identity for the stream
stream_uuid = UUID.uuid4()

# a new stream will be created when the expected version is zero
expected_version = 0

# list of events to persist
events = [
  %EventStore.EventData{
    headers: %{user: "someuser@example.com"},
    payload: %ExampleEvent{key: "value"}
  }
]

# append events to stream
{:ok, events} = EventStore.append_to_stream(store, stream_uuid, expected_version, events)

Reading Events

# read all events from the stream, starting at the beginning (as from version is 0)
{:ok, recorded_events} = EventStore.read_stream_forward(store, uuid, 0)

Benchmark EventStore performance

Run the benchmark suite using mix with the bench environment, as configured in config/bench.exs. Logging is disabled for benchmarking.

MIX_ENV=bench mix do es.reset, app.start, bench