[HIVE-13019] Optimizer COLLECT_LIST/COLLECT_SET

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: CBO, Logical Optimizer
• Assignee: Unassigned
• Reporter: Dustin Cote
• Created: 06/Feb/16 21:27
• Updated: 12/May/16 17:52

Description

Currently when using a COLLECT_SET/COLLECT_LIST that involves data from a single table, the aggregation is done after any JOIN operation that is present in the query. For example:

insert into table nested_customers_orders
select c.*, collect_list(named_struct("oid", o.oid, "order_date": o.date...))
from customers c inner join orders o on (c.cid = o.oid)
group by o.oid, o.date,...

If we can tell the optimizer to perform the COLLECT_LIST first (where possible) we can see some performance gains in this pattern of query.

Issue Links

• relates to: HIVE-13076 Implement FK/PK "rely novalidate" constraints for better CBO