[CASSANDRA-11834] Don't compute expensive MaxPurgeableTimestamp until we've verified there's an expired tombstone

• Type: Bug
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 2.1.15, 2.2.7
• Component/s: Local/Compaction
• Severity: Low
• Assignee: Jonathan Ellis
• Reporter: Jonathan Ellis

Authors

Jonathan Ellis

Reviewers

Marcus Eriksson

• Created: 18/May/16 16:31
• Updated: 16/Apr/19 09:30
• Resolved: 18/May/16 17:32

Description

In LCR's get reduced, we currently do this:

                if (t.timestamp() < getMaxPurgeableTimestamp() && t.data.isGcAble(controller.gcBefore))

Should call the expensive getMaxPurgeableTimestamp only after we have called the cheap isGcAble.

Marking this as a bug since it can cause pathological performance problems (CASSANDRA-11831).

Have verified that this is not a problem in 3.0 (CompactionIterator does the check in the correct order).