[IMPALA-8791] Handle the case where there is no fragment scheduled on the coordinator for a query

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Product Backlog
• Fix Version/s: Impala 3.4.0
• Epic Color: ghx-label-5
• Assignee: Bikramjeet Vig
• Reporter: Bikramjeet Vig
• Created: 24/Jul/19 23:02
• Updated: 05/Sep/19 18:21
• Resolved: 05/Sep/19 18:21

Description

For insert statements executed on a dedicated coord, the fragments get schduled only on executors but a query state object still gets started up on the coord host with the coord_mem_limit. we end up with a situation where the mem admitted is zero for the coord but the mem_reserved is non-zero which would affect other admission decisions.

There is also a case where there is no coordinator fragment but the execution fragment gets scheduled on the coord (eg. insert into <tbl> values....) for this case, the mem admitted is per_backend_mem_limit_ but the mem limit applied to the coord query state is coord_backend_mem_limit_ which again causes a inconsistency.