[jira] [Assigned] (CASSANDRA-11106) Experiment with strategies for picking compaction candidates in LCS

["Dikang Gu (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-11106?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dikang Gu reassigned CASSANDRA-11106:
-------------------------------------

    Assignee: Dikang Gu

> 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
>            Assignee: Dikang Gu
>              Labels: lcs
>             Fix For: 3.x
>
>
> 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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