             warning  : 30          # display warning and stop using connection if run takes this many seconds or more
             error    : 10*60       # kill any query that takes this long (and corresponding connection)
             concurrent_warn : 500  # if number of concurrent outstanding db queries exceeds this number, put a concurrent_warn message in the log.
+            mod_warn : 2           # display MOD_WARN warning in log if any query modifies at least this many docs
             cb       : undefined
         dbg = @dbg('constructor')
 

                                @_stats ?= {sum:0, n:0}
                                @_stats.sum += tm
                                @_stats.n += 1
                                winston.debug("[#{that._concurrent_queries} concurrent]   rethink: query time using (#{id}) took #{tm}ms; average=#{Math.round(@_stats.sum/@_stats.n)}ms;  -- '#{query_string}'")
                            if err
                                report_time()
                                if err.message.indexOf('is closed') != -1

        @_num_connections  = opts.pool
        @_warning_thresh   = opts.warning
        @_error_thresh     = opts.error
        @_mod_warn         = opts.mod_warn
        @_concurrent_warn  = opts.concurrent_warn
        @_all_hosts        = opts.all_hosts

