[CASSANDRA-19381] StreamingTombstoneHistogramBuilder.DataHolder does not merge histogram points correctly on overflow

• Type: Bug
• Status: In Progress
• Priority: Normal
• Resolution: Unresolved
• Fix Version/s: 5.0.x, 5.x
• Component/s: Local/SSTable
• Bug Category: Degradation - Performance Bug/Regression
• Severity: Normal
• Complexity: Normal
• Discovered By: Code Inspection
• Platform: All

Source Control Link

https://github.com/apache/cassandra/pull/3136

Test and Documentation Plan

Added unit tests

• Assignee: Ariel Weisberg
• Reporter: Ariel Weisberg

Authors

Ariel Weisberg

Reviewers

Berenguer Blasi

• Created: 08/Feb/24 23:12
• Updated: 18/Jul/24 21:15

Description

The algorithm tries to merge the two nearest points in the histogram and create a new point that is in between the two merged points based on the weight of each point. This can overflow long arithmetic with the code that is currently there  and the work around is pick one of the points and just put it there.

This can be worked around by changing the midpoint calculation to not overflow.