[KYLIN-4492] Bad query leads to full gc

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: v3.1.0
• Component/s: Query Engine
• Sprint: Sprint 52
• Assignee: Zhong Yanghong
• Reporter: Zhong Yanghong
• Created: 12/May/20 06:02
• Updated: 10/Jul/20 11:43
• Resolved: 03/Jun/20 14:47

Description

The following sql goes into dead loop of RuleQueue.popMatch() in VolcanoPlanner.findBestExp() leading to OOM

select LSTG_FORMAT_NAME,
 cast(sum(t.sid_cnt) as bigint) as sid_cnts
from
 (select LSTG_FORMAT_NAME,
 count(distinct SELLER_ID) as sid_cnt
 from TEST_KYLIN_FACT
 group by LSTG_FORMAT_NAME) t
group by LSTG_FORMAT_NAME
order by sid_cnts