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From "Marcus Eriksson (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-11106) Experiment with strategies for picking compaction candidates in LCS
Date Tue, 02 Feb 2016 09:34:39 GMT
Marcus Eriksson created CASSANDRA-11106:
-------------------------------------------

             Summary: Experiment with strategies for picking compaction candidates in LCS
                 Key: CASSANDRA-11106
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11106
             Project: Cassandra
          Issue Type: Improvement
            Reporter: Marcus Eriksson


Ideas taken here: http://rocksdb.org/blog/2921/compaction_pri/

Current strategy in LCS is that we keep track of the token that was last compacted and then
we start a compaction with the sstable containing the next token (kOldestSmallestSeqFirst
in the blog post above)

The rocksdb blog post above introduces a few ideas how this could be improved:
* pick the 'coldest' sstable (sstable with the oldest max timestamp) - we want to keep the
hot data (recently updated) in the lower levels to avoid write amplification
* pick the sstable with the highest tombstone ratio, we want to get tombstones to the top
level as quickly as possible.



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