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From Peter Schuller <>
Subject Re: How fast does compaction run?
Date Wed, 20 Oct 2010 17:24:38 GMT
> We are using 0.6.1, and are planning to upgrade to 0.6.6.  Currently, we are
> observing that the compaction is going at the rate about ~10MB per second.
> We did not see obvious bottleneck hardware wise.
> Is this normal, or did we miss something?

Assuming you're otherwise not entirely saturating and hitting a
bottleneck, likely your compaction is CPU bound in a single thread.
Whether compaction will be CPU bound or disk bound will depend a lot
on your data; in general, more smaller columns are more CPU intensive
while fewer large columns will tend to be more disk bound.

Unless you have a problem with compaction speed not staying caught up
with write speeds, this is not necessarily bad as it limits the impact
of compaction on disk I/O (i.e., less negative effects for real
traffic assuming real traffic goes down to disk and isn't entirely

/ Peter Schuller

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