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From Peter Schuller <>
Subject Re: Question re: the use of multiple ColumnFamilies
Date Tue, 18 Jan 2011 15:56:48 GMT
> Sorry for the delayed reply, but thanks very much - this pointed me at the
> exact problem. I found that the queue size here was equal to the number of
> configured DataFileDirectories, so a good test was to lie to Cassandra and
> claim that there were more DataFileDirectories than I needed. Interestingly,
> it still only ever wrote to the first configured DataFileDirectory, but it
> certainly eliminated the problem, which I think means that for my use case
> at least, it will be good enough to patch Cassandra to introduce more
> control of the queue size.

Based on your use case as you originally stated it (some cf:s that got
written at a slow pace and just happened to flush at the same time),
that should be enough.

(If you have some CF:s being written to faster than they are flushed,
there would still be potential for one CF to hog the flush writers

/ Peter Schuller

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