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From Peter Schuller <>
Subject Re: Capacity problem with a lot of writes?
Date Fri, 26 Nov 2010 15:49:06 GMT
> Making compaction parallel isn't a priority because the problem is
> almost always the opposite: how do we spread it out over a longer
> period of time instead of sharp spikes of activity that hurt
> read/write latency.  I'd be very surprised if latency would be
> acceptable if you did have parallel compaction.  In other words, your
> real problem is you need more capacity for your workload.

Do you expect this to be true even with the I/O situation improved
(i.e., under conditions where the additional I/O is not a problem)? It
seems counter-intuitive to me that single-core compaction would make a
huge impact on latency when compaction is CPU bound on a 8+ core
system under moderate load (even taking into account cache
coherency/NUMA etc).

/ Peter Schuller

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