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

Disclaimer: The information contained in this message and attachments is intended solely for the attention and use of the named addressee and may be confidential. If you are not the intended recipient, you are reminded that the information remains the property of the sender. You must not use, disclose, distribute, copy, print or rely on this e-mail. If you have received this message in error, please contact the sender immediately and irrevocably delete this message and any copies.