[jira] [Updated] (CASSANDRA-4565) TTL columns with older then gcgrace do not need to flush

["Edward Capriolo (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-4565?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Edward Capriolo updated CASSANDRA-4565:
---------------------------------------

    Attachment: cassandra-4565.patch.1.txt

First attempt at a patch. Test passes, but we will likely refine this later.
                
> TTL columns with older then gcgrace do not need to flush
> --------------------------------------------------------
>
>                 Key: CASSANDRA-4565
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4565
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Edward Capriolo
>            Assignee: Edward Capriolo
>         Attachments: cassandra-4565.patch.1.txt
>
>
> With memcache many people are willing to sacrifice durability for performance. Cassandra has a TimeToLive feature that can be used in caching scenarios with low values for gc_grace_seconds. However from a code dive it seems that cassandra will always write TTL to disk, even those that are beyond gc_grace_seconds. If a user very large memtables,small ttl, and low gc_grace it is possible that writing memtables can be skipped entirely in some scenarios.

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