cat big{1,2,3}.txt | ./linux-q -tT "select c1, sum(c2) from - group by c1 order by sum(c2) desc, c1" >out.txt

real time: 84.027 seconds

./linux-q -tT "select c1, sum(c2) from big[1-3].txt group by c1 order by sum(c2) desc, c1" >out.txt

real time: 89.539 seconds