# File lib/memcache/pg_server.rb, line 106
    def prepend(key, value)
      delete_expired(key)
      result = db.exec %{
        UPDATE #{table}
          SET value = #{quote(value)} || value, updated_at = NOW()
          WHERE key = #{quote(key)} AND #{prefix_clause}
      }
      result.cmdtuples == 1
    end