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From Romain HARDOUIN <romain.hardo...@urssaf.fr>
Subject Re: keyspace with hundreds of columnfamilies
Date Wed, 02 Jul 2014 16:35:51 GMT
Arena allocation is an improvement feature, not a limitation. 
It was introduced in Cassandra 1.0 in order to lower memory fragmentation 
(and therefore promotion failure).
AFAIK It's not intended to be tweaked so it might not be a good idea to 
change it.

Best,
Romain

tommaso barbugli <tbarbugli@gmail.com> a écrit sur 02/07/2014 17:40:18 :

> De : tommaso barbugli <tbarbugli@gmail.com>
> A : user@cassandra.apache.org, 
> Date : 02/07/2014 17:40
> Objet : Re: keyspace with hundreds of columnfamilies
> 
> 1MB per column family sounds pretty bad to me; is this something I 
> can tweak/workaround somehow?
> 
> Thanks
> Tommaso
> 

> 2014-07-02 17:21 GMT+02:00 Romain HARDOUIN <romain.hardouin@urssaf.fr>:
> The trap is that each CF will consume 1 MB of memory due to arena 
allocation. 
> This might seem harmless but if you plan thousands of CF it means 
> thousands of mega bytes... 
> Up to 1,000 CF I think it could be doable, but not 10,000. 
> 
> Best, 
> 
> Romain 
> 
> 
> tommaso barbugli <tbarbugli@gmail.com> a écrit sur 02/07/2014 10:13:41 :
> 
> > De : tommaso barbugli <tbarbugli@gmail.com> 
> > A : user@cassandra.apache.org, 
> > Date : 02/07/2014 10:14 
> > Objet : keyspace with hundreds of columnfamilies 
> > 
> > Hi, 
> > Are there any known issues, shortcomings about organising data in 
> > hundreds of column families? 
> > At this present I am running with 300 column families but I expect 
> > that to get to a couple of thousands. 
> > Is this something discouraged / unsupported (I am using Cassandra 
2.0). 
> > 
> > Thanks 
> > Tommaso
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