Extensions

FerricStore ships with extension packages that integrate with the Elixir ecosystem.

Overview

Session Store

Package: ferricstore_session Drop-in replacement for: Cookie store or ETS session store Key benefit: Sessions survive deploys, restarts, and node failures

# mix.exs
{:ferricstore_session, "~> 0.3.5"}

# In your Phoenix endpoint:
plug Plug.Session,
  store: FerricStore.Session.Store,
  key: "_my_app_key",
  ttl: 3600,
  prefix: "sess"

Unlike cookie sessions (4KB limit, client-side), FerricStore sessions are server-side with no size limit. Unlike ETS sessions, they persist on disk — deploying your app doesn't log out your users.

Ecto L2 Cache

Package: ferricstore_ecto Drop-in replacement for: use Ecto.Repo Key benefit: Automatic caching for Ecto with zero code changes

Quick Start

# 1. Switch your Repo (one-line change)
defmodule MyApp.Repo do
  use FerricStore.Ecto.CachedRepo,  # was: use Ecto.Repo
    otp_app: :my_app,
    adapter: Ecto.Adapters.Postgres
end

# 2. Mark schemas as cacheable
defmodule MyApp.User do
  use Ecto.Schema
  use FerricStore.Ecto.Cacheable, ttl: :timer.minutes(10)

  schema "users" do
    field :name, :string
    field :email, :string
    timestamps()
  end
end

# 3. Existing code works unchanged
Repo.get(User, 42)     # DB hit, cached
Repo.get(User, 42)     # cache hit, no DB
Repo.update(changeset)  # cache invalidated automatically

When to Use

• You have read-heavy schemas where the same rows are fetched repeatedly
• You want caching without manual cache key management
• You want automatic invalidation on every mutation (no stale data bugs)
• You have reference data tables (countries, currencies) that rarely change

When NOT to Use

• Write-heavy tables (audit logs, event streams) -- don't add Cacheable
• Tables where every read is unique (complex analytics queries)
• When you need sub-millisecond read latency for already-fast DB queries

Schema Configuration

Per-Query Control

Repo.get(User, 42)                     # default: read cache, populate on miss
Repo.get(User, 42, cache: false)       # bypass cache entirely
Repo.get(User, 42, cache: :refresh)    # skip read, repopulate from DB
Repo.get(User, 42, cache: :cache_only) # cache only, no DB fallback
Repo.get(User, 42, cache: [ttl: ms])   # custom TTL for this read

See the full README for the complete invalidation flow, field serialization details, before/after comparisons, and testing setup.

Architecture

Your Application
├── MyApp.Repo (Ecto API)
│   └── FerricStore.Ecto.CachedRepo
│       └── FerricstoreEcto.Cache
│           └── FerricStore
│               Keys: ecto:users:42
│               Keys: ecto:gen:users
│               Keys: ecto:q:123:g0:pks
│
└── FerricStore Supervision Tree
    ├── Store.Router (shard routing)
    ├── Store.Shard (per-shard GenServer)
    └── Bitcask (persistent storage engine)

Dependencies

The extension packages depend on ferricstore (the core engine). You must have FerricStore configured and running in your application's supervision tree before using any extension. See the Getting Started guide for FerricStore setup.

Version Compatibility