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To: user@cassandra.apache.org
Subject: Re: about multitenant datamodel
References: <op.wet910ngxfu728@rbxc0734.mlab.csk.com>
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Date: Fri, 08 Jun 2012 18:20:17 +0900
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From: Toru Inoko <inoko@ms.scsk.jp>
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> See virtual keyspaces in Hector.
Yes, at first, I tried to desigen data model like POD architecture  =

(http://goo.gl/Uw1yD) with this.
But, it is problem for me that strong consistency isn't guaranteed among=
  =

metadata schemas.

> Every CF has a certain amount of overhead in memory. It's just not how=
  =

> Cassandra is designed to be used.
Thanks. I'll try to design meta schma data model again which has strong =
 =

consistency.

Thank you for your advices!

On Wed, 06 Jun 2012 03:35:40 +0900, aaron morton <aaron@thelastpickle.co=
m>  =

wrote:

>> 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 wit=
h  =

> 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 ho=
w  =

>> 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 yo=
u  =

>> 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=E2=80=A6)
>> It's not keyspaces, but the number of column families.
>>
>> Without storing any data each CF uses about 1MB of ram. When they sta=
rt  =

>> 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 d=
o  =

>> 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 spac=
e.
>>
>> | 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.
>>
>>
>>
>>

>>
>>
>>
>>
>> --
>> With kind regards,
>>
>> Robin Verlangen
>> Software engineer
>>
>> W http://www.robinverlangen.nl
>> E robin@us2.nl
>>
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>


-- =

-----------------------------------
SCSK Corp.

Toru Inoko
tel       : 03-6438-3544
mail      : inoko@ms.scsk.jp
-----------------------------------