[IMPALA-7731] Add ratio between scanned and transmitted bytes to fragment instances

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 3.1.0
• Fix Version/s: Impala 3.2.0
• Component/s: Backend
• Labels: observability supportability
• Epic Link: Improve Impala Profile User Experience
• Epic Color: ghx-label-3
• Assignee: Lars Volker
• Reporter: Lars Volker
• Created: 19/Oct/18 17:03
• Updated: 14/Mar/19 14:33
• Resolved: 25/Jan/19 17:57

Description

Selective scans (and by extension selective fragment instances) take higher performance hits when reading data remotely. They can be identified by a low ratio between data being transmitted vs data being read from HDFS. To make it easier to spot those instances we should add this ratio to each instance and to the root of the execution profile.