[HIVE-5555] Support alternate join syntax: joining conditions in where clause; also pushdown qualifying join conditions

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: Query Processor
• Assignee: Harish Butani
• Reporter: Harish Butani
• Created: 16/Oct/13 00:50
• Updated: 07/Feb/14 10:41

Description

Certain tools still generate `old style' Join queries where the join
condition is in the Where clause. A related set of issues that can
be addressed is that of pushing forward joining conditions;
in a manner similar to the Predicate Pushdown feature of Hive.

For e.g. these queries can have join conditions pushed down:

- query 1, push join predicate from 2nd join to 1st
explain select *
from part p1 join part p2 join part p3 on p1.p_name = p2.p_name and p2.p_name = p3.p_name;

- query 2
explain select *
from part p1 join part p2 join part p3 
where p1.p_name = p2.p_name and p2.p_name = p3.p_name;

Issue Links

• depends upon: HIVE-5552 Merging of QBJoinTrees doesn't handle filter pushdowns correctly
• relates to: HIVE-5558 Support alternate join syntax

Sub-Tasks

• Pushdown join conditions: Resolved
• Push down qualifying Where clause predicates as join conditions: Resolved
• Support alternate join syntax: Resolved
• Remove predicates that are pushed forward as join conditions from where clause: Open