[HIVE-15474] Extend limit propagation for chain of RS-GB-RS operators

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.2.0
• Fix Version/s: 2.2.0
• Component/s: Physical Optimizer
• Assignee: Jesús Camacho Rodríguez
• Reporter: Jesús Camacho Rodríguez
• Created: 20/Dec/16 11:57
• Updated: 27/Feb/24 22:24
• Resolved: 06/Jan/17 09:31

Description

The goal is to extend the work started in HIVE-14002.

For instance, given the following query:

explain
select key, value, count(key + 1) as agg1 from src 
group by key, value
order by key, value, agg1 limit 20;

We generate the following physical plan:
TS1 - GBY2 - RS3 - GBY4 - RS5 - SEL6 - LIM7 - FS8

We can push the limit to RS3 operator, as we will generate records for the top N keys, and thus, GBY4 will produce the top N results. However, currently we do not do it.

Issue Links

• relates to: HIVE-14002 Extend limit propagation to subsequent RS operators