[jira] [Created] (TAJO-585) Empty table makes result zero in union query.

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

Jaehwa Jung created TAJO-585:
--------------------------------

             Summary: Empty table makes result zero in union query.
                 Key: TAJO-585
                 URL: https://issues.apache.org/jira/browse/TAJO-585
             Project: Tajo
          Issue Type: Bug
          Components: physical operator
            Reporter: Jaehwa Jung


I found a bug when I used empty table which located on local file system in union query as follows:
{code:xml}
tajo> select * from table1;
result: file:/tmp/tajo-blrunner/staging/q_1391568986216_0001/RESULT, 5 rows (72 B)
id,  name,  score,  type
-------------------------------
1,  ooo,  1.1,  a
2,  ppp,  2.3,  b
3,  qqq,  3.4,  c
4,  rrr,  4.5,  d
5,  xxx,  5.6,  e

tajo> select * from table2;
result: file:/tmp/tajo-blrunner/staging/q_1391568986216_0002/RESULT, 0 rows (0 B)
id,  name,  score,  type,  part
-------------------------------

tajo> select id, name from table2 union select id, name from table1 ;
result: file:/tmp/tajo-blrunner/staging/q_1391576101475_0003/RESULT, 5 rows (42 B)
id,  name
-------------------------------
1,  ooo
2,  ppp
3,  qqq
4,  rrr
5,  xxx

tajo> select id, name from table1 union select id, name from table2 ;
result: file:/tmp/tajo-blrunner/staging/q_1391576101475_0002/RESULT, 0 rows (42 B)
id,  name
-------------------------------

{code}

In this case, empty table order affected result. And I created tables as follows:
{code:xml}
CREATE EXTERNAL TABLE table1 (id INT4, name TEXT, score FLOAT4, type TEXT) USING CSV WITH ('csvfile.delimiter'='|') LOCATION 'hdfs://localhost:9010/tajo/warehouse/table1';

CREATE EXTERNAL TABLE table2 (id INT4, name TEXT, score FLOAT4, type TEXT) USING CSV WITH ('csvfile.delimiter'='|') LOCATION 'file:/tmp/tajo-blrunner/warehouse/table2';
{code}



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