db/primary_migrate/20191022134041_add_uniqueness_constraint_to_unconfirmed_emails.rb
class AddUniquenessConstraintToUnconfirmedEmails < ActiveRecord::Migration[5.1]
disable_ddl_transaction!
def change
add_index(
:email_addresses,
%i[email_fingerprint user_id],
unique: true,
algorithm: :concurrently,
)
end
end