[CASSANDRA-3325] Compaction degrades key cache stats

• Type: Bug
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 1.0.0
• Labels: compaction
• Severity: Low
• Assignee: Fabien Rousseau
• Reporter: Fabien Rousseau

Authors

Fabien Rousseau

Reviewers

Jonathan Ellis

• Created: 06/Oct/11 10:29
• Updated: 16/Apr/19 09:32
• Resolved: 06/Oct/11 16:05

Description

When "compaction_preheat_key_cache" is set to true, then during compaction, it keep tracks of cached keys to to re-cache their new position.
It does this by calling the following method on every key of the compacted sstable :
sstable.getCachedPosition(row.key)
which also update cache stats, thus lowering hit rate

Below is an attached patch allowing to know if the key is cached, but without updating the stats.