Uni Ecto Plugin -

def get_orders_with_global_settings do query = from o in Order, join: s in Setting, on: true, # Global join select: o, s Repo.all(query, prefix: UniEcto.Plugin.get_tenant_prefix()) end Handling Migrations with The Plugin The trickiest part of multi-tenancy is database schema updates. You cannot just run mix ecto.migrate .

def call(conn, _opts) do # Extract subdomain or API key tenant = get_tenant_from_subdomain(conn) uni ecto plugin

defmodule MyApp.Repo do use Ecto.Repo, otp_app: :my_app use UniEcto.Plugin, prefix_key: :tenant_prefix def all_tenants do # Could be a DB query or a static list ["public", "tenant_customer_a", "tenant_customer_b"] end end Step 3: Generate the Tenant Migrations The plugin usually provides a generator: def get_orders_with_global_settings do query = from o in

# config/config.exs config :uni_ecto_plugin, :cache, enabled: true, ttl: :timer.hours(1) The plugin will cache the list of valid tenants in an ETS table. Validating a prefix becomes an O(1) memory read instead of a SQL query. 1. The "Prefix Not Set" Error Error: (Ecto.NoResultsError) expected query to return a prefix, but none was set Fix: Ensure your TenantResolver plug runs before any database calls in your controller pipeline. 2. Association Loading Fails If you have a belongs_to across schemas, Ecto may struggle with prefixes. Fix: Define associations with explicit prefixes or use Repo.assoc with the tenant prefix manually. Validating a prefix becomes an O(1) memory read

defmodule MyApp.Repo.Migrations.AddNotesToOrders do use Ecto.Migration import UniEcto.MigrationHelpers def up do # Runs on all existing tenants + public for tenant <- UniEcto.Plugin.all_tenants() do execute("SET search_path TO #tenant") alter table(:orders) do add :notes, :text end end end end