diff --git a/backend/controller/sql/schema/001_init.sql b/backend/controller/sql/schema/001_init.sql
index 66238ae7fe..de06503fe9 100644
--- a/backend/controller/sql/schema/001_init.sql
+++ b/backend/controller/sql/schema/001_init.sql
@@ -43,9 +43,7 @@ CREATE TABLE modules
 -- Proto-encoded module schema.
 CREATE DOMAIN module_schema_pb AS BYTEA;
 
-CREATE DOMAIN runner_key AS varchar;
-CREATE DOMAIN controller_key AS varchar;
-CREATE DOMAIN deployment_key AS varchar;
+CREATE DOMAIN deployment_key AS VARCHAR;
 
 CREATE TABLE deployments
 (
@@ -106,6 +104,8 @@ CREATE TYPE runner_state AS ENUM (
     'dead'
     );
 
+CREATE DOMAIN runner_key AS VARCHAR;
+
 -- Runners are processes that are available to run modules.
 CREATE TABLE runners
 (
@@ -216,6 +216,8 @@ CREATE TYPE controller_state AS ENUM (
     'dead'
     );
 
+CREATE DOMAIN controller_key AS VARCHAR;
+
 CREATE TABLE controller
 (
     id        BIGINT           NOT NULL GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
@@ -263,9 +265,12 @@ CREATE INDEX events_custom_key_2_idx ON events (custom_key_2);
 CREATE INDEX events_custom_key_3_idx ON events (custom_key_3);
 CREATE INDEX events_custom_key_4_idx ON events (custom_key_4);
 
+CREATE DOMAIN topic_key AS VARCHAR;
+
 -- Topics are a way to asynchronously publish data between modules.
 CREATE TABLE topics (
     id BIGINT NOT NULL GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+    "key" topic_key UNIQUE NOT NULL,
     created_at TIMESTAMPTZ NOT NULL DEFAULT (NOW() AT TIME ZONE 'utc'),
 
     -- Each topic is associated with an owning module.
@@ -302,11 +307,14 @@ CREATE TRIGGER topic_events_notify_event
     FOR EACH ROW
 EXECUTE PROCEDURE notify_event();
 
+CREATE DOMAIN subscription_key AS VARCHAR;
+
 -- A subscription to a topic.
 --
 -- Multiple subscribers can consume from a single subscription.
 CREATE TABLE topic_subscriptions (
     id BIGINT NOT NULL GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+    "key" subscription_key UNIQUE NOT NULL,
     created_at TIMESTAMPTZ NOT NULL DEFAULT (NOW() AT TIME ZONE 'utc'),
 
     topic_id BIGINT NOT NULL REFERENCES topics(id) ON DELETE CASCADE,
@@ -318,11 +326,14 @@ CREATE TABLE topic_subscriptions (
     cursor BIGINT NOT NULL REFERENCES topic_events(id) ON DELETE CASCADE
 );
 
+CREATE DOMAIN subscriber_key AS VARCHAR;
+
 -- A subscriber to a topic.
 --
 -- A subscriber is a 1:1 mapping between a subscription and a sink.
 CREATE TABLE topic_subscribers (
    id BIGINT NOT NULL GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+   "key" subscriber_key UNIQUE NOT NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT (NOW() AT TIME ZONE 'utc'),
 
    topic_subscriptions_id BIGINT NOT NULL REFERENCES topic_subscriptions(id),