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From tommaso barbugli <tbarbu...@gmail.com>
Subject Re: keyspace with hundreds of columnfamilies
Date Wed, 02 Jul 2014 18:16:44 GMT
Hi,
thank you for you replies on this; regarding the arena memory is this a
fixed memory allocation or is some sort of in memory caching? I ask because
I think that a substantial portion of the column families created will not
be queried that frequently (and some will become inactive and stay like
that really long time)

Thank you,
Tommaso


2014-07-02 18:35 GMT+02:00 Romain HARDOUIN <romain.hardouin@urssaf.fr>:

> 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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