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From Patrick Julien <pjul...@gmail.com>
Subject Re: Pyramid Organization of Data
Date Thu, 14 Apr 2011 20:57:03 GMT
On Thu, Apr 14, 2011 at 4:47 PM, Adrian Cockcroft
<acockcroft@netflix.com> wrote:
> What you are asking for breaks the eventual consistency model, so you need to create
a separate cluster in NYC that collects the same updates but has a much longer setting to
timeout the data for deletion, or doesn't get the deletes.
>
> One way is to have a trigger on writes on your pyramid nodes in NY that copies data over
to the long term analysis cluster. The two clusters won't be eventually consistent in the
presence of failures, but with RF=3 you will get up to three triggers for each write, so you
get three chances to get the copy done.
>


Yes, that's one of the scenarios we're contemplating.  However, there
aren't any triggers at the cassandra level and even if they were, we
would get them multiple times.

So far, I believe my best bet is to run 2 clusters.  One global that
has NY and the satellite sites.  The other is NY specific and is the
archive site.

We would then make placement strategy in NY that would decorate the
configured placement strategy so that it would copy the row over to
the archive site before passing it into the non-archive NY cluster.

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