On 3/12/2012 6:52 AM, Brandon Williams wrote: > On Mon, Mar 12, 2012 at 4:44 AM, aaron morton <aa...@thelastpickle.com> wrote: >> I don't understand why I >> don't get multiple concurrent compactions running, that's what would >> make the biggest performance difference. >> >> concurrent_compactors >> Controls how many concurrent compactions to run, by default it's the number >> of cores on the machine. I'm on a quad-core machine so not setting concurrent_compactors should not be a limiting factor... > With leveled compaction, I don't think you get any concurrency because > it has to compact an entire level, and it can't proceed to the next > level without completing the one before it. > > In short, if you want maximum throughput, stick with size tiered. I switched the CFs to tiered compaction and I still get no concurrency for the same CF. I now have two compactions running concurrently but always for different CFs. I've briefly seen a third for one of the small CFs, so it's willing to run more than two concurrently. Looks like I have to wait for a few days for all the compactions to complete. Talk about compaction hell!
> > -Brandon >
