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https://issues.apache.org/jira/browse/CASSANDRA-4565?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13443295#comment-13443295
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Edward Capriolo commented on CASSANDRA-4565:
--------------------------------------------
I noticed this because the method I added had loggers that I never saw in the
output. What I saw happening was ExpiringColumns past TTL never made it into
the flush. After some tracing I came to the conclusion that
maybeResetDeletionTimes takes into account ttl time, and converts them to
DeletedColumns which do not get flushed.
Also if you take the unit test I added, it passes without modification to the
code base so unless my test is not doing what I think it seems like cassandra
is already handling this.
If you are finding this not to be the case we can re-open and I will take a
look.
> 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
> Fix For: 1.3
>
> 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 use case very large memtables,small ttl, and
> small gc_grace it is possible that flushing these columns to disk can be
> skipped entirely in some scenarios.
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