[CASSANDRA-7272] Add "Major" Compaction to LCS and split sstables during STCS major compaction

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 2.2.0 beta 1
• Labels: compaction lcs
• Impacts: Docs
• Assignee: Marcus Eriksson
• Reporter: T Jake Luciani

Authors

Marcus Eriksson

Reviewers

Carl Yeksigian

• Created: 20/May/14 13:23
• Updated: 06/Nov/19 22:04
• Resolved: 02/Apr/15 07:58

Description

LCS has a number of minor issues (maybe major depending on your perspective).

LCS is primarily used for wide rows so for instance when you repair data in LCS you end up with a copy of an entire repaired row in L0. Over time if you repair you end up with multiple copies of a row in L0 - L5. This can make predicting disk usage confusing.

Another issue is cleaning up tombstoned data. If a tombstone lives in level 1 and data for the cell lives in level 5 the data will not be reclaimed from disk until the tombstone reaches level 5.

I propose we add a "major" compaction for LCS that forces consolidation of data to level 5 to address these.

Issue Links

• relates to: CASSANDRA-7019 Improve tombstone compactions
• relates to: CASSANDRA-8671 Give compaction strategy more control over where sstables are created, including for flushing and streaming.