add template_id to submitters

db/migrate/20261025120000_add_template_id_to_submitters.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddTemplateIdToSubmitters < ActiveRecord::Migration[8.1]
+  def change
+    add_column :submitters, :template_id, :bigint, if_not_exists: true
+  end
+end

db/migrate/20261025120001_populate_submitter_template_id.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+class PopulateSubmitterTemplateId < ActiveRecord::Migration[8.1]
+  disable_ddl_transaction!
+
+  class MigrationSubmitter < ApplicationRecord
+    self.table_name = 'submitters'
+  end
+
+  class MigrationSubmission < ApplicationRecord
+    self.table_name = 'submissions'
+  end
+
+  def up
+    return if ENV['MULTITENANT'] == 'true'
+
+    max_id = MigrationSubmitter.maximum(:id)
+
+    return unless max_id
+
+    submission_template_id =
+      Arel::Nodes::Grouping.new(
+        MigrationSubmission.arel_table.project(MigrationSubmission.arel_table[:template_id])
+                           .where(MigrationSubmission.arel_table[:id].eq(MigrationSubmitter.arel_table[:submission_id]))
+                           .ast
+      )
+
+    (1..max_id).step(10_000) do |start_id|
+      MigrationSubmitter.where(template_id: nil, id: start_id...(start_id + 10_000))
+                        .update_all(template_id: submission_template_id)
+    end
+  end
+
+  def down
+    nil
+  end
+end

db/migrate/20261025120002_add_submitters_template_id_indexes.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class AddSubmittersTemplateIdIndexes < ActiveRecord::Migration[8.1]
+  def up
+    add_index :submitters, %i[email template_id], where: 'email IS NOT NULL', if_not_exists: true
+    add_index :submitters, %i[template_id id], if_not_exists: true
+    remove_index :submitters, :email, if_exists: true
+  end
+
+  def down
+    add_index :submitters, :email, if_not_exists: true
+    remove_index :submitters, %i[template_id id], if_exists: true
+    remove_index :submitters, %i[email template_id], if_exists: true
+  end
+end