Add example db migration file for aggregate unique keys

CHANGELOG.md

@@ -4,6 +4,9 @@
   transaction is committed, reducing the need for having aggregates to
   ensure uniqueness or relying on projectors. See
   lib/sequent/core/helpers/unique_keys.rb for details.
+
+  This feature requires a new database, you can find an example
+  migration at `db/migrate/20250108162754_aggregate_unique_keys.rb`.
 - `CommandHandlerHelpers` has been updated to:
   - Load aggregates using the `given_events` so that unique keys can
     be tested. This may require changing your test to correctly set up

db/migrate/20250108162754_aggregate_unique_keys.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+class AggregateUniqueKeys < ActiveRecord::Migration[7.2]
+  def up
+    say 'Setting up search path', true
+    suppress_messages do
+      execute <<~SQL
+        SELECT set_config('tmp.search_path', current_setting('search_path'), true);
+        SELECT set_config('search_path', '#{Sequent.configuration.event_store_schema_name}', true);
+      SQL
+    end
+
+    say 'Creating aggregate_unique_keys table', true
+    suppress_messages do
+      execute <<~SQL
+        CREATE TABLE IF NOT EXISTS aggregate_unique_keys (
+            aggregate_id uuid NOT NULL,
+            scope text NOT NULL,
+            key jsonb NOT NULL,
+            PRIMARY KEY (aggregate_id, scope),
+            UNIQUE (scope, key),
+            FOREIGN KEY (aggregate_id) REFERENCES aggregates (aggregate_id) ON UPDATE CASCADE ON DELETE CASCADE
+        )
+      SQL
+    end
+
+    say 'Creating event store stored procedures and views', true
+    suppress_messages do
+      sequent_pgsql_filename = File.join(Sequent.configuration.database_schema_directory, 'sequent_pgsql.sql')
+      execute File.read(sequent_pgsql_filename)
+    end
+
+    say 'Restoring search path', true
+    suppress_messages do
+      execute "SELECT set_config('search_path', current_setting('tmp.search_path'), true)"
+    end
+  end
+
+  def down
+    fail ActiveRecord::IrreversibleMigration
+  end
+end