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From Jonathan Ellis <>
Subject Re: Alternative to repair
Date Mon, 07 Mar 2011 18:22:36 GMT
On Mon, Mar 7, 2011 at 11:18 AM, Daniel Doubleday
<> wrote:
> Since we already have a very simple hadoopish framework in place which allows us to do
token range walks with multiple workers and restart at a given position in case of failure
I created a simple worker that would read everything with CL_ALL. With only one worker and
almost no performance impact one scan took 7h.
> My understanding is that at that point due to read repair I got the same as I would have
achieved with repair runs.

Not really:

- range scans do not perform read repair
- if you converted it to range scan + [multi]get, the RR messages are
fair game to drop to cope with load ("active" repair messages are
never dropped in 0.6.7+)

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support

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