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From Zhu Han <schumi....@gmail.com>
Subject Re: RFC: Cassandra Virtual Nodes
Date Sat, 24 Mar 2012 03:50:22 GMT
On Sat, Mar 24, 2012 at 7:55 AM, Peter Schuller <peter.schuller@infidyne.com
> wrote:

> > No I don't think you did, in fact, depending on the size of your SSTable
> a
> > contiguous range (or the entire SSTable) may or may not be affected by a
> > cleanup/move or any type of topology change. There is lots of room for
> > optimization here. After loading the indexes we actually know start/end
> > range for an SSTable so we can include/exclude it in any such operation
>
>
> Just note that unless there is some correlation between range and
> these sstables being created to begin with (like with leveled), you're
> highly unlikely to be able to optimize here. For uniformly distributed
> tokens (hashed keys), all sstables are likely to have almost the
> entire possible token range in them.
>

As Peter pointed out, for random partitioner, the rows of  a specific range
might scatter around all sstables.

Unless whole sstable can be ignored, disk seek is the performance killer
here.




> --
> / Peter Schuller (@scode, http://worldmodscode.wordpress.com)
>

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