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From aaron morton <aa...@thelastpickle.com>
Subject Re: about multitenant datamodel
Date Tue, 05 Jun 2012 18:35:40 GMT
> With an abstraction layer you can store practically anything in Cassandra.
See virtual keyspaces in Hector. 

> why do you think so? I'll let users create ristricted CFs, and limit a number of CFs
which users create.
> is it still a bad one?
Depends what your limits are, but in general still yes. 

If someone creates a CF with 10 secondary indexes they will use more resources than someone
who creates a CF with none. Same thing would happen in a multitenant RDBMS server. 

If you have 200 CF's in a cluster it will use more memory than one with 20 CF's. The extra
memory use will result in more disk IO.

Cheers


-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 5/06/2012, at 7:52 PM, R. Verlangen wrote:

> Every CF has a certain amount of overhead in memory. It's just not how Cassandra is designed
to be used. Maybe you could think of a way to smash data down to indices and entities. With
an abstraction layer you can store practically anything in Cassandra.
> 
> 2012/6/5 Toru Inoko <inoko@ms.scsk.jp>
> IMHO a model that allows external users to create CF's is a bad one.
> 
> why do you think so? I'll let users create ristricted CFs, and limit a number of CFs
which users create.
> is it still a bad one?
> 
> 
> On Thu, 31 May 2012 06:44:05 +0900, aaron morton <aaron@thelastpickle.com> wrote:
> 
> - Do a lot of keyspaces cause some problems? (If I have 1,000 users, cassandra creates
1,000 keyspaces…)
> It's not keyspaces, but the number of column families.
> 
> Without storing any data each CF uses about 1MB of ram. When they start storing and reading
data they use more.
> 
> IMHO a model that allows external users to create CF's is a bad one.
> 
> Hope that helps.
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
> 
> On 25/05/2012, at 12:52 PM, Toru Inoko wrote:
> 
> Hi, all.
> 
> I'm designing data api service(like cassandra.io but not using dedicated server for each
user) on cassandra 1.1 on which users can do DML/DDL method like cql.
> Followings are api which users can use( almost same to cassandra api).
> - create/read/delete ColumnFamilies/Rows/Columns
> 
> Now I'm thinking about multitenant datamodel on that.
> My data model like the following.
> I'm going to prepare a keyspace for each user as a user's tenant space.
> 
> | keyspace1 | --- | column family |
> |(for user1)|  |
>              ...
> 
> | keyspace2 | --- | column family |
> |(for user2)|  |
>              ...
> 
> Followings are my question!
> - Is this data model a good for multitenant?
> - Do a lot of keyspaces cause some problems? (If I have 1,000 users, cassandra creates
1,000 keyspaces...)
> 
> please, help.
> thank you in advance.
> 
> Toru Inoko.
> 
> 
> 
> 
> -- 
> -----------------------------------
> SCSK株式会社
> 技術・品質・情報グループ 技術開発部
> 先端技術課
> 
> 猪子 徹(Toru Inoko)
> tel       : 03-6438-3544
> mail      : inoko@ms.scsk.jp
> -----------------------------------
> 
> 
> 
> 
> -- 
> With kind regards,
> 
> Robin Verlangen
> Software engineer
> 
> W http://www.robinverlangen.nl
> E robin@us2.nl
> 
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