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From Franc Carter <franc.car...@sirca.org.au>
Subject Re: Number of keyspaces
Date Wed, 23 May 2012 01:52:20 GMT
On Wed, May 23, 2012 at 7:42 AM, aaron morton <aaron@thelastpickle.com>wrote:

> 1 KS with 24 CF's will use roughly the same resources as 24 KS's with 1
> CF. Each CF:
>
> * loads the bloom filter for each SSTable
> * samples the index for each sstable
> * uses row and key cache
> * has a current memtable and potentially memtables waiting to flush.
> * had secondary index CF's
>
> I would generally avoid a data model that calls for CF's to be added in
> response to new entities or new data. Older data will move moved to larger
> files, and not included in compaction for newer data.
>

We were thinking of doing a major compaction after each year is 'closed
off'. This would mean that compactions for the current year were dealing
with a smaller amount of data and hence be faster and have less impact on a
day-to-day basis. Our query patterns will only infrequently cross year
boundaries.

Are we being naive ?

cheers


>
> Hope that helps.
>
>   -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 23/05/2012, at 3:31 AM, Luís Ferreira wrote:
>
> I have 24 keyspaces, each with a columns family and am considering
> changing it to 1 keyspace with 24 CFs. Would this be beneficial?
> On May 22, 2012, at 12:56 PM, samal wrote:
>
> Not ideally, now cass has global memtable tuning. Each cf correspond to
> memory  in ram. Year wise cf means it will be in read only state for next
> year, memtable  will still consume ram.
> On 22-May-2012 5:01 PM, "Franc Carter" <franc.carter@sirca.org.au> wrote:
>
>> On Tue, May 22, 2012 at 9:19 PM, aaron morton <aaron@thelastpickle.com>wrote:
>>
>>> It's more the number of CF's than keyspaces.
>>>
>>
>> Oh - does increasing the number of Column Families affect performance ?
>>
>> The design we are working on at the moment is considering using a Column
>> Family per year. We were thinking this would isolate compactions to a more
>> manageable size as we don't update previous years.
>>
>> cheers
>>
>>
>>>
>>> Cheers
>>>
>>>   -----------------
>>> Aaron Morton
>>> Freelance Developer
>>> @aaronmorton
>>> http://www.thelastpickle.com
>>>
>>> On 22/05/2012, at 6:58 PM, R. Verlangen wrote:
>>>
>>> Yes, it does. However there's no real answer what's the limit: it
>>> depends on your hardware and cluster configuration.
>>>
>>> You might even want to search the archives of this mailinglist, I
>>> remember this has been asked before.
>>>
>>> Cheers!
>>>
>>> 2012/5/21 Luís Ferreira <zamith.28@gmail.com>
>>>
>>>> Hi,
>>>>
>>>> Does the number of keyspaces affect the overall cassandra performance?
>>>>
>>>>
>>>> Cumprimentos,
>>>> Luís Ferreira
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> With kind regards,
>>>
>>> Robin Verlangen
>>> www.robinverlangen.nl
>>>
>>>
>>>
>>
>>
>> --
>> *Franc Carter* | Systems architect | Sirca Ltd
>>  <marc.zianideferranti@sirca.org.au>
>> franc.carter@sirca.org.au | www.sirca.org.au
>> Tel: +61 2 9236 9118
>>  Level 9, 80 Clarence St, Sydney NSW 2000
>> PO Box H58, Australia Square, Sydney NSW 1215
>>
>>
>  Cumprimentos,
> Luís Ferreira
>
>
>
>
>


-- 

*Franc Carter* | Systems architect | Sirca Ltd
 <marc.zianideferranti@sirca.org.au>

franc.carter@sirca.org.au | www.sirca.org.au

Tel: +61 2 9236 9118

Level 9, 80 Clarence St, Sydney NSW 2000

PO Box H58, Australia Square, Sydney NSW 1215

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