mastodon/db/migrate/20200521180606_encrypted_message_ids_to_timestamp_ids.rb

class EncryptedMessageIdsToTimestampIds < ActiveRecord::Migration[5.2]
  def up
    safety_assured do
      execute("ALTER TABLE encrypted_messages ALTER COLUMN id SET DEFAULT timestamp_id('encrypted_messages')")
    end
  end

  def down
    execute("LOCK encrypted_messages")
    execute("SELECT setval('encrypted_messages_id_seq', (SELECT MAX(id) FROM encrypted_messages))")
    execute("ALTER TABLE encrypted_messages ALTER COLUMN id SET DEFAULT nextval('encrypted_messages_id_seq')")
  end
end