I understand that. The overhead could be as high as 10x of memtable data size. So overall the overhead for 16CF collectively in your case could be 300*10 = 3G.
Thanks, Naren On Wed, Mar 23, 2011 at 11:18 AM, ruslan usifov <ruslan.usi...@gmail.com>wrote: > > > 2011/3/23 Narendra Sharma <narendra.sha...@gmail.com> > >> I think it is due to fragmentation in old gen, due to which survivor area >> cannot be moved to old gen. 300MB data size of memtable looks high for 3G >> heap. I learned that in memory overhead of memtable can be as high as 10x of >> memtable data size in memory. So either increase the heap or reduce the >> memtable thresholds further so that old gen gets freed up faster. With >> 16CFs, I would do both i.e. increase the heap to say 4GB and reduce memtable >> thresholds further. >> >> >> I think that you don't undestend me, 300MB is a summary thresholds on all > 16 CF, so one memtable_threshold is about 18MB. Or all the same it is > necessary to reduce memtable_threshold?
