[HIVE-20621] GetOperationStatus called in resultset.next causing incremental slowness

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.2.0, 4.0.0
• Fix Version/s: 3.2.0, 4.0.0-alpha-1
• Component/s: JDBC
• Target Version/s: 3.2.0, 4.0.0
• Assignee: Prasanth Jayachandran
• Reporter: Prasanth Jayachandran
• Created: 22/Sep/18 00:42
• Updated: 17/Nov/22 08:54
• Resolved: 23/Sep/18 08:25

Description

Fetching result set for a result cache hit query gets slower as more rows are fetched. For fetching 10 row result set it took about 900ms but fetching 200 row result set took 8 seconds. 

Reason for this slowness is GetOperationStatus is invoked inside resultset.next() and it happens for every row even after operation has completed. This is one RPC call per row fetched (there is also connection overhead without keepalive). 

Issue Links

• is related to: KNOX-1524 Hive "select *" performance evaluation