[jira] [Created] (TAJO-702) ORDER BY DESC query sends all datas to single task.

["hyoungjunkim (JIRA)" <ji...@apache.org>]

hyoungjunkim created TAJO-702:
---------------------------------

             Summary: ORDER BY DESC query sends all datas to single task.
                 Key: TAJO-702
                 URL: https://issues.apache.org/jira/browse/TAJO-702
             Project: Tajo
          Issue Type: Improvement
            Reporter: hyoungjunkim
            Priority: Minor


I ran TPC-H Q10 with scale 100. Last execution block for ORDER BY had 10 tasks. But single task received all datas.
{code}
select c_custkey, c_name, sum(l_extendedprice * (1 - l_discount)) as revenue, c_acctbal, n_name, c_address, c_phone, c_comment from customer as c join nation as n on c.c_nationkey = n.n_nationkey join orders as o on c.c_custkey = o.o_custkey and o.o_orderdate >= '1993-10-01' and o.o_orderdate < '1994-01-01' join lineitem as l on l.l_orderkey = o.o_orderkey and l.l_returnflag = 'R' group by c_custkey, c_name, c_acctbal, c_phone, n_name, c_address, c_comment order by revenue desc
{code}

I found some bug in UniformRangePartition class. UniformRangePartition's increment() method  always add value to inc regardless of the sort order. So, Range values ​​are generated as follows.
{noformat}
(0=>936768.8469000002) ~ (0=>1030364.8469000002)
(0=>1030364.8469000002) ~ (0=>1123960.8469000002)
(0=>1123960.8469000002) ~ (0=>1217556.8469000002)
(0=>1217556.8469000002) ~ (0=>1311152.8469000002)
(0=>1311152.8469000002) ~ (0=>1404748.8469000002)
(0=>1404748.8469000002) ~ (0=>1498344.8469000002)
(0=>1498344.8469000002) ~ (0=>1591940.8469000002)
(0=>1591940.8469000002) ~ (0=>1685536.8469000002)
(0=>1685536.8469000002) ~ (0=>1779132.8469000002)
(0=>1779132.8469000002) ~ (0=>817.902)
{noformat}



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