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From Vitalii Tymchyshyn <>
Subject Re: Max # of CFs
Date Tue, 20 Mar 2012 15:09:06 GMT

 From my experience it's unwise to make many column families for same 
keys because you will have bloom filters and row indexes multiplied. If 
you have 5000, you should expect your heap requirements multiplied by 
same factor. Also check your cache sizes. Default AFAIR is 100000 keys 
per column family.

20.03.12 16:05, A J написав(ла):
> ok, the last thread says that 1.0+ onwards, thousands of CFs should
> not be a problem.
> But I am finding that all the allocated heap memory is getting consumed.
> I started with 8GB heap and then on reading
> realized that minimum of 1MB per memtable is used by the per-memtable
> arena allocator.
> So with 5K CFs, 5GB will be used just by arena allocators.
> But even on increasing the heap to 16GB, am finding that all the heap
> is getting consumed. Is there a different formula for heap calculation
> when you have thousands of CFs ?
> Any other configuration that I need to change ?
> Thanks.
> On Mon, Mar 19, 2012 at 10:35 AM, Alain RODRIGUEZ<>  wrote:
>> This subject was already discussed, this may help you :
>> If you still got questions after reading this thread or some others about
>> the same topic, do not hesitate asking again,
>> Alain
>> 2012/3/19 A J<>
>>> How many Column Families are one too many for Cassandra ?
>>> I created a db with 5000 CFs (I can go into the reasons later) but the
>>> latency seems to be very erratic now. Not sure if it is because of the
>>> number of CFs.
>>> Thanks.

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