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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Using ttl to expire columns rather than using delete
Date Wed, 12 Oct 2011 07:17:19 GMT
Unfortunately, expiring column are no magic bullet. If you insert
columns with ttl=1,
you're roughly doing the same thing than deleting, so the exact same
rule concerning
repair applies.

What can be said on repair and expiring columns (and that may or may
not be helpful)
is that if you have a column family on which all and every column you
insert has a
ttl > n (for some n, including n = infinity) and ttl are your only
means of deletion for
that CF (i.e, no deletes), then it would be enough to run repair on
that column family
only every gc_grace + n period of time (instead of every gc_grace period).

--
Sylvain

On Wed, Oct 12, 2011 at 3:49 AM, Terry Cumaranatunge <cumarana@gmail.com> wrote:
> Hello,
>
> If you set a ttl and expire a column, I've read that this eventually turns
> into a tombstone and will be cleaned out by the GC. Are expirations
> considered a form of delete that still requires a node repair to be run in
> gc_grace_period seconds? The operations guide says you have to run node
> repair if you have deletes, so I'm trying to find out if we can upsert the
> column with expirations using a ttl=1 to substitute deletes. The node repair
> operations is very intensive in our environment and causes a
> significant performance degradation on the system.
>
> Thanks

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