Janaki Lahorani created HIVE-20570:
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Summary: Union ALL with hive.optimize.union.remove=true has
incorrect plan
Key: HIVE-20570
URL: https://issues.apache.org/jira/browse/HIVE-20570
Project: Hive
Issue Type: Bug
Reporter: Janaki Lahorani
When hive.optimize.union.remove=true and a select query is run with group by,
the final fetch is waiting only for one of the branches and not both.
Test Case:
{code}
create table if not exists test_table(column1 string, column2 int);
insert into test_table values('a',1),('b',2);
set hive.optimize.union.remove=true;
set mapred.input.dir.recursive=true;
explain
select column1 from test_table group by column1
union all
select column1 from test_table group by column1;
{code}
In the below the two stages correspond to the two parts of union all. But the
final fetch operator (Stage 0) only depends on one of the stages, but it should
depend on both.
Plan:
{code}
STAGE DEPENDENCIES:
Stage-1 is a root stage
Stage-2 is a root stage
* Stage-0 depends on stages: Stage-1*
STAGE PLANS:
Stage: Stage-1
Map Reduce
Map Operator Tree:
TableScan
alias: test_table
Statistics: Num rows: 2 Data size: 6 Basic stats: COMPLETE Column
stats: NONE
Select Operator
expressions: column1 (type: string)
outputColumnNames: column1
Statistics: Num rows: 2 Data size: 6 Basic stats: COMPLETE Column
stats: NONE
Group By Operator
keys: column1 (type: string)
mode: hash
outputColumnNames: _col0
Statistics: Num rows: 2 Data size: 6 Basic stats: COMPLETE
Column stats: NONE
Reduce Output Operator
key expressions: _col0 (type: string)
sort order: +
Map-reduce partition columns: _col0 (type: string)
Statistics: Num rows: 2 Data size: 6 Basic stats: COMPLETE
Column stats: NONE
Execution mode: vectorized
Reduce Operator Tree:
Group By Operator
keys: KEY._col0 (type: string)
mode: mergepartial
outputColumnNames: _col0
Statistics: Num rows: 1 Data size: 3 Basic stats: COMPLETE Column
stats: NONE
File Output Operator
compressed: false
Statistics: Num rows: 1 Data size: 3 Basic stats: COMPLETE Column
stats: NONE
table:
input format: org.apache.hadoop.mapred.SequenceFileInputFormat
output format:
org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat
serde: org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe
Stage: Stage-2
Map Reduce
Map Operator Tree:
TableScan
alias: test_table
Statistics: Num rows: 2 Data size: 6 Basic stats: COMPLETE Column
stats: NONE
Select Operator
expressions: column1 (type: string)
outputColumnNames: column1
Statistics: Num rows: 2 Data size: 6 Basic stats: COMPLETE Column
stats: NONE
Group By Operator
keys: column1 (type: string)
mode: hash
outputColumnNames: _col0
Statistics: Num rows: 2 Data size: 6 Basic stats: COMPLETE
Column stats: NONE
Reduce Output Operator
key expressions: _col0 (type: string)
sort order: +
Map-reduce partition columns: _col0 (type: string)
Statistics: Num rows: 2 Data size: 6 Basic stats: COMPLETE
Column stats: NONE
Execution mode: vectorized
Reduce Operator Tree:
Group By Operator
keys: KEY._col0 (type: string)
mode: mergepartial
outputColumnNames: _col0
Statistics: Num rows: 1 Data size: 3 Basic stats: COMPLETE Column
stats: NONE
File Output Operator
compressed: false
Statistics: Num rows: 1 Data size: 3 Basic stats: COMPLETE Column
stats: NONE
table:
input format: org.apache.hadoop.mapred.SequenceFileInputFormat
output format:
org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat
serde: org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe
Stage: Stage-0
Fetch Operator
limit: -1
Processor Tree:
ListSink
{code}
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