An empty memtable would not take up much space, a few KB I would assume. However they are considered in the calculations that control how frequently to flush to disk. The more CF's, even if they do not have data, the more frequently you will flush to disk.
Cheers ----------------- Aaron Morton Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 23/07/2013, at 6:06 PM, Michał Michalski <mich...@opera.com> wrote: > Not sure how up-to-date this info is, but from some discussions that happened > here long time ago I remember that a minimum of 1MB per Memtable needs to be > allocated. > > The other constraint here is memtable_total_space_in_mb setting in > cassandra.yaml, which you might wish to tune when having a lot of CFs. > > M. > > W dniu 23.07.2013 07:12, Darren Smythe pisze: >> The way weve gone about our data models has resulted in lots of column >> families and just looking for guidelines about how much space each column >> table adds. >> >> TIA >> >> >> On Sun, Jul 21, 2013 at 11:19 PM, Darren Smythe <darren1...@gmail.com>wrote: >> >>> Hi, >>> >>> How much overhead (in heap MB) does an empty memtable use? If I have many >>> column families that aren't written to often, how much memory do these take >>> up? >>> >>> TIA >>> >>> -- Darren >>> >> >
