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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Does counter columns support TTL
Date Thu, 17 Feb 2011 18:21:41 GMT
On Thu, Feb 17, 2011 at 6:19 PM, Utku Can Topçu <utku@topcu.gen.tr> wrote:

> And I think this patch would still be useful and legitimate if the TTL of
> the initial increment is taken into account.


This is still broken for the same reason.

The problem is that the live-time of a given update depends on when it gets
resolved to other udpates. It makes the observed behavior dependent on when
compaction run which is not something you want to depend on. Whether you
keep the TTL of the oldest or newest column when you resolve doesn't change
that.

The feature works fine only if you set TTL that are larger that the worst
time it will take to do a major compaction. Otherwise it doesn't work.
That's the technical part.

Now, whether this is a good idea to add a feature that has this limitation
is a bit more a matter of opinion. My own opinion right now is that the risk
are too great and as such I advise against it (unless I'm missing something
here).

--
Sylvain


>
>
> On Thu, Feb 17, 2011 at 6:11 PM, Utku Can Topçu <utku@topcu.gen.tr> wrote:
>
>> Yes, I've read the discussion. My use-case is similar to the use-case of
>> the contributor.
>>
>> So that's the reason why I've asked if it works or not. (with the flaw of
>> course).
>>
>>
>>
>>
>> On Thu, Feb 17, 2011 at 5:41 PM, Jonathan Ellis <jbellis@gmail.com>wrote:
>>
>>> If you read the discussion on that ticket, the point is that the
>>> approach is fundamentally flawed.
>>>
>>> On Thu, Feb 17, 2011 at 10:16 AM, Utku Can Topçu <utku@topcu.gen.tr>
>>> wrote:
>>> > Can anyone confirm that this patch works with the current trunk?
>>> >
>>> > On Thu, Feb 17, 2011 at 4:16 PM, Sylvain Lebresne <
>>> sylvain@datastax.com>
>>> > wrote:
>>> >>
>>> >> https://issues.apache.org/jira/browse/CASSANDRA-2103
>>> >>
>>> >> On Thu, Feb 17, 2011 at 4:05 PM, Utku Can Topçu <utku@topcu.gen.tr>
>>> wrote:
>>> >>>
>>> >>> Hi All,
>>> >>>
>>> >>> I'm experimenting and developing using counters. However, I've come
>>> to a
>>> >>> usecase where I need counters to expire and get deleted after a
>>> certain time
>>> >>> of inactivity (i.e. have countercolumn deleted one hour after the
>>> last
>>> >>> increment).
>>> >>>
>>> >>> As far as I can tell counter columns don't have TTL in the thrift
>>> >>> interface, is it because of a limitation of the counter
>>> implementation?
>>> >>>
>>> >>> Regards,
>>> >>> Utku
>>> >>>
>>> >>>
>>> >>
>>> >
>>> >
>>>
>>>
>>>
>>> --
>>> Jonathan Ellis
>>> Project Chair, Apache Cassandra
>>> co-founder of Riptano, the source for professional Cassandra support
>>> http://riptano.com
>>>
>>
>>
>

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