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From Ryan King <r...@twitter.com>
Subject Re: data distribution among DataFileDirectories
Date Tue, 29 Sep 2009 20:55:43 GMT
On Tue, Sep 29, 2009 at 12:46 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
> On Tue, Sep 29, 2009 at 2:22 PM, Igor Katkov <ikatkov@gmail.com> wrote:
>> Does cassandra distributes keys evenly among DataFileDirectories?
>
> No, but it should distribute sstables evenly (which, on average,
> should be distributing keys evenly, but there will be large variance).
>
>> Questions:
>> 1. Is it by design?
>
> Each time a sstable is created, either by flush or compaction, it
> should pick the "next" directory to use.
>
>> 2. Is there a way to control key distribution, for the cases when
>> hard-drives are of different capacity?
>
> No.  (That wouldn't be hard to add, but nobody's needed it.)

We would certainly like to have it at twitter. We've been thinking
it'd be nice to have separate data directories per column family.

-ryan

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