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https://issues.apache.org/jira/browse/CASSANDRA-4565?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13453697#comment-13453697
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Aleksey Yeschenko commented on CASSANDRA-4565:
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bq. Not sure how this will work if a total column with a shorter total shadows
a title column with a longer ttl. Then lost update might be an issue.
Or a column with tll shadowing a regular column with no ttl at all. This ttl
change will be lost.
I'm certain that nothing can be done about it. Turning them into tombstones is
an option though.
[~jbellis] there is a solution for 4542, but only because we know that if a row
is in the memtable it can't exist in any of the sstables. I can implement that
at least.
> 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: Aleksey Yeschenko
> 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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