[IMPALA-9722] Consolidate unused total_width and the way avg_width is computed in PerColumnStats

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Impala 4.0.0
• Component/s: Backend
• Labels: statistics
• Epic Color: ghx-label-8
• Assignee: Tamas Mate
• Reporter: Tamas Mate
• Created: 02/May/20 09:45
• Updated: 11/May/20 15:52
• Resolved: 11/May/20 14:01

Description

PerColumnStats.total_width is an unused field in incr-stats-util.cc while the comment says that it is the result of (avg_width * num_rows). Later similar multiplication can be found in the Update method, however the result is stored in avg_width.

avg_width += (new_avg_width * num_new_rows);

We should consolidate these fields and the calculations.