[IMPALA-12056] Child queries could get scheduled on improper executor group sets

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: Impala 4.3.0
• Epic Color: ghx-label-10
• Assignee: Riza Suminto
• Reporter: Abhishek Rawat
• Created: 11/Apr/23 13:48
• Updated: 14/Jul/23 09:20
• Resolved: 04/May/23 15:59

Description

'Compute Stats' queries gets scheduled on the smallest executor group set since these queries don't do any real work. However their child queries also gets scheduled on the smallest executor group. This may not be ideal for cases where the child query does NDVs and Counts on a big wide table. We should assign the executor group set for the children queries based on their planning estimates.

Today we see following message for the parent query, which. makes sense:

Verdict: Assign to first group because query is not auto-scalable 

as a side effect we see following message for child queries:

Verdict: query option REQUEST_POOL=root.group-set-small is set. Memory and cpu limit checking is skipped.