Harish Butani created HIVE-5710:
-----------------------------------
Summary: Merging of Join Trees assumes all filters are on the
merging table
Key: HIVE-5710
URL: https://issues.apache.org/jira/browse/HIVE-5710
Project: Hive
Issue Type: Bug
Reporter: Harish Butani
Assignee: Harish Butani
The following query fails with a SemanticException
{noformat}
select p1.name, p2.name, p3.name
from part p1 join p2 on p1.name = p2.name
join part p3 on p1.name = p3.name and p2.key > 10
{noformat}
The Merge Join logic associates the p2.key > 10 filter with the merging table
i.e 'p1'. When constructing the Join Plan an attempt is made to resolve this
predicate against p1's RowResolver which causes the SemanticException.
The underlying issue is that during runtime filters are applied on the input
rows to the Join Operator. There is no way to apply a filter on intermediate
data. In the above query we shouldn't apply p2.key >10 predicate directly on
p2, but on the output of p1 join p2.
The following is also a valid query, here the predicate refers to multiple left
tables:
{noformat}
select p1.name, p2.name, p3.name
from part p1 join p2 on p1.name = p2.name
join part p3 on p1.name = p3.name and p2.key > p1.key
{noformat}
As a start, propose to prevent merging when there is a Filter that refers to a
non-merging table.
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