[TAJO-926] Join condition including column references of a row-preserving table in left outer join causes incorrect result

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.9.0
• Component/s: Physical Operator, Planner/Optimizer
• Assignee: Hyunsik Choi
• Reporter: Hyunsik Choi
• Created: 09/Jul/14 07:57
• Updated: 11/Jul/14 09:33
• Resolved: 11/Jul/14 09:19

Description

This patch fixes two bugs.

One is wrong projection push down (PPD). See the example, reproducing the bug:

select
  r_name,
  r_regionkey,
  n_name,
  n_regionkey
from
  region left outer join nation on n_regionkey = r_regionkey and r_name in ('AMERICA', 'ASIA')
order by r_name;

The above query includes one left outer join (LOJ) and one join filter. Since this join filter R_NAME in ('AMERICA', 'ASIA') includes column references corresponding to the row preserved table region, the join filter is placed on the LOJ operator. It only results in the sub expression push down of RowConstantEval and replaces right expression of IN predicate by FieldEval. But, we assume that the RHS of InEval is always RowConstantEval. This is the main clause of this bug.

2014-07-09 16:39:37,527 ERROR: org.apache.tajo.worker.Task (run(395)) - org.apache.tajo.engine.eval.FieldEval cannot be cast to org.apache.tajo.engine.eval.RowConstantEval
java.lang.ClassCastException: org.apache.tajo.engine.eval.FieldEval cannot be cast to org.apache.tajo.engine.eval.RowConstantEval
	at org.apache.tajo.engine.eval.InEval.eval(InEval.java:62)
	at org.apache.tajo.engine.eval.BinaryEval.eval(BinaryEval.java:104)
	at org.apache.tajo.engine.planner.physical.NLLeftOuterJoinExec.next(NLLeftOuterJoinExec.java:109)
	at org.apache.tajo.engine.planner.physical.ExternalSortExec.sortAndStoreAllChunks(ExternalSortExec.java:201)
	at org.apache.tajo.engine.planner.physical.ExternalSortExec.next(ExternalSortExec.java:278)
	at org.apache.tajo.engine.planner.physical.RangeShuffleFileWriteExec.next(RangeShuffleFileWriteExec.java:99)
	at org.apache.tajo.worker.Task.run(Task.java:388)
	at org.apache.tajo.worker.TaskRunner$1.run(TaskRunner.java:406)
	at java.lang.Thread.run(Thread.java:744)
2014-07-09 16:39:37,528 INFO: org.apache.tajo.worker.TaskAttemptContext (setState(115)) - Query status of ta_1404891573341_0004_000003_000000_02 is changed to TA_FAILED
2014-07-09 16:39:37,529 INFO: org.apache.tajo.worker.Task (run(452)) - Worker's task counter - total:3, succeeded: 0, killed: 3, failed: 3

The second bug is that HashLeftOuterJoin results in wrong result when it has join filter corresponding to row preserved table like the above example query.
In order to fix this bug, we have to skip the right iterator of hash table when if the joined tuple is filtered.

Expected:

r_name,r_regionkey,n_name,n_regionkey
-------------------------------
AFRICA,0,null,null
AMERICA,1,ARGENTINA,1
AMERICA,1,BRAZIL,1
AMERICA,1,CANADA,1
AMERICA,1,PERU,1
AMERICA,1,UNITED STATES,1
ASIA,2,INDIA,2
ASIA,2,INDONESIA,2
ASIA,2,JAPAN,2
ASIA,2,CHINA,2
ASIA,2,VIETNAM,2
EUROPE,3,null,null
MIDDLE EAST,4,null,null

Actual result:

r_name,r_regionkey,n_name,n_regionkey
-------------------------------
AFRICA,0,null,null
AFRICA,0,null,null
AFRICA,0,null,null
AFRICA,0,null,null
AFRICA,0,null,null
AMERICA,1,ARGENTINA,1
AMERICA,1,BRAZIL,1
AMERICA,1,CANADA,1
AMERICA,1,PERU,1
AMERICA,1,UNITED STATES,1
ASIA,2,INDIA,2
ASIA,2,INDONESIA,2
ASIA,2,JAPAN,2
ASIA,2,CHINA,2
ASIA,2,VIETNAM,2
EUROPE,3,null,null
EUROPE,3,null,null
EUROPE,3,null,null
EUROPE,3,null,null
EUROPE,3,null,null
MIDDLE EAST,4,null,null
MIDDLE EAST,4,null,null
MIDDLE EAST,4,null,null
MIDDLE EAST,4,null,null
MIDDLE EAST,4,null,null