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https://issues.apache.org/jira/browse/CASSANDRA-5149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13587006#comment-13587006
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Sylvain Lebresne commented on CASSANDRA-5149:
---------------------------------------------
bq. I have trouble coming up with a use case for it.
You mean, for querying the expiration time of a column? My own experience with
TTL leads me to believe that anyone using expiring columns will want to query
the expiration time at one point or another. I personally had a case where if
some TTLed columns were read, we were "extending" the TTL and how long it was
extended depended on the current expiration time. Or, on the other end of the
spectrum, wanting to update a column value without extending the TTL. I had
also a number of case where not all columns had the same TTL, if any, and just
knowing if the column was an expiring one was necessary (including but not
limited to checking during development that the code was doing what it was
supposed to do in terms of setting TTLs).
Also, if we were to transform expiring column to standard column on read, even
ignoring the fact that we wouldn't be able to return the expiration time to
clients, you'd have to be careful about read-repair "cancelling" your TTLs.
Besides, as said above, especially if it's fix-for 2.0 (and so things like
"this may require a protocol change" become largely irrelevant), I think
normalizing all code on having expiration be based on a time fixed at well know
places (like we do for gcBefore really) is the right long term solution.
> Respect slice count even if column expire mid-request
> -----------------------------------------------------
>
> Key: CASSANDRA-5149
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5149
> Project: Cassandra
> Issue Type: Bug
> Affects Versions: 0.7.0
> Reporter: Sylvain Lebresne
> Fix For: 2.0
>
>
> This is a follow-up of CASSANDRA-5099.
> If a column expire just while a slice query is performed, it is possible for
> replicas to count said column as live but to have the coordinator seeing it
> as dead when building the final result. The effect that the query might
> return strictly less columns that the requested slice count even though there
> is some live columns matching the slice predicate but not returned in the
> result.
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