Merge failing of join tree in exceptional case
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Key: HIVE-2253
URL: https://issues.apache.org/jira/browse/HIVE-2253
Project: Hive
Issue Type: Bug
Components: Query Processor
Affects Versions: 0.7.0
Environment: hadoop 0.20.2, hive 0.7.0
Reporter: Navis
Priority: Minor
In some very exceptional cases, SemanticAnayzer fails to merge join tree.
Example is below.
create table a (val1 int, val2 int)
create table b (val1 int, val2 int)
create table c (val1 int, val2 int)
create table d (val1 int, val2 int)
create table e (val1 int, val2 int)
1. all same(single) join key --> one MR, good
select * from a join b on a.val1=b.val1 join c on a.val1=c.val1 join d on
a.val1=d.val1 join e on a.val1=e.val1
2. two join keys --> expected to have two MR, but resulted to three MR
select * from a join b on a.val1=b.val1 join c on a.val1=c.val1 join d on
a.val1=d.val1 join e on a.val2=e.val2
3. by changing the join order, we could attain two MR as first-expectation.
select * from a join e on a.val2=e.val2 join c on a.val1=c.val1 join d on
a.val1=d.val1 join b on a.val1=b.val1
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