[CASSANDRA-13664] RangeFetchMapCalculator should not try to optimise 'trivial' ranges

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 4.0-alpha1, 4.0
• Severity: Normal
• Assignee: Marcus Eriksson
• Reporter: Marcus Eriksson

Authors

Marcus Eriksson

Reviewers

Ariel Weisberg

• Created: 04/Jul/17 12:28
• Updated: 15/May/20 08:00
• Resolved: 14/Aug/17 12:35

Description

RangeFetchMapCalculator (CASSANDRA-4650) tries to make the number of streams out of each node as even as possible.

In a typical multi-dc ring the nodes in the dcs are setup using token + 1, creating many tiny ranges. If we only try to optimise over the number of streams, it is likely that the amount of data streamed out of each node is unbalanced.

We should ignore those trivial ranges and only optimise the big ones, then share the tiny ones over the nodes.