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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Long-life TTL and extending TTL
Date Mon, 10 Sep 2012 13:40:01 GMT
> Is there any way of updating the TTL without being in need of rewriting the data back
again?

No, there isn't.


> If not, is running a Map/Reduce task on the whole data set the "best" option

If the TTL is made rather infrequently and on a large percentage of
the data, which seems to be your case, then that's likely the option I
would use.


> My last question is regarding to a long term TTL, does this have any
> negative impact on the cluster?

The main drawback of TTL is that each column has a 8 bytes overhead (a
tad more details here:
http://www.datastax.com/dev/blog/whats-new-cassandra-07-expiring-columns).
It's not a big deal imo, especially now that we have compression, but
it's worth knowing. There is nothing specific to having "long term"
TTL in any case.

--
Sylvain

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