[CASSANDRA-5263] Increase merkle tree depth as needed

• Type: Improvement
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 2.1.1
• Component/s: Legacy/Streaming and Messaging
• Labels: repair
• Assignee: Yuki Morishita
• Reporter: Ahmed Bashir

Authors

Yuki Morishita

Reviewers

Jonathan Ellis

• Created: 15/Feb/13 06:17
• Updated: 16/Apr/19 09:32
• Resolved: 27/Jun/14 17:28

Description

Currently, the maximum depth allowed for Merkle trees is hardcoded as 15. This value should be configurable, just like phi_convict_treshold and other properties.

Given a cluster with nodes responsible for a large number of row keys, Merkle tree comparisons can result in a large amount of unnecessary row keys being streamed.

Empirical testing indicates that reasonable changes to this depth (18, 20, etc) don't affect the Merkle tree generation and differencing timings all that much, and they can significantly reduce the amount of data being streamed during repair.