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From "Jeremiah Jordan" <JEREMIAH.JOR...@morningstar.com>
Subject RE: Queries on AuthN and AuthZ for multi tenant Cassandra
Date Thu, 02 Feb 2012 16:20:47 GMT
10-15 KS should be fine.  The issue is when you want to have hundreds or
thousands of KS/CF.

-Jeremiah

-----Original Message-----
From: Subrahmanya Harve [mailto:subrahmanyaharve@gmail.com] 
Sent: Thursday, February 02, 2012 1:43 AM
To: dev@cassandra.apache.org
Subject: Re: Queries on AuthN and AuthZ for multi tenant Cassandra

Thanks for the response Aaron.

We do not anticipate more than 10-15 tenants on the cluster. Even if one
does decide to create one KS/tenant, there is the problem of variable
loads
on the KS's. I went through this link
http://www.datastax.com/dev/blog/whats-new-in-cassandra-1-0-improved-mem
ory-and-disk-space-managementwhich
does promise better memory management. I did have two more questions
-
- Was the new memory management written taking into account a situation
of
many KS's? (In other words, did multi-tenancy influence the re-design of
memory management?)
- i know that users trying out multi-tenancy are generally recommending
not
to create many Ks's/CF's, but i am wondering if there is any
documentation
for why this happens or the details on the negative impact on
memory/performance?and are there are any performance benchmarks
available
for Cassandra 1.0 clusters with many KS's?


On Wed, Feb 1, 2012 at 12:11 PM, aaron morton
<aaron@thelastpickle.com>wrote:

> The existing authentication plug-in does not support row level
> authorization.
>
> You will need to add authentication to your API layer to ensure that a
> request from client X always has the client X key prefix. Or modify
> cassandra to provide row level authentication.
>
> The 1.x Memtable memory management is awesome, but I would still be
> hesitant about creating KS's and CF's at the request of an API client.
>
> Cheers
>
>
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 2/02/2012, at 8:52 AM, Subrahmanya Harve wrote:
>
> > We are using Cassandra 0.8.7 and building a multi-tenant cassandra
> platform
> > where we have a common KS and common CFs for all tenants. By using
> Hector's
> > virtual keyspaces, we are able to add modify rowkeys to have a
tenant
> > specific id. (Note that we do not allow tenants to modify/create
KS/CF.
> We
> > just allow tenants to write and read data) However we are in the
process
> of
> > adding authentication and authorization on top of this platform such
that
> > no tenant should be able to retrieve data belonging to any other
tenant.
> >
> > By configuring Cassandra for security using the documentation here -
> > http://www.datastax.com/docs/0.8/configuration/authentication , we
were
> > able to apply the security constraints on the common keyspace and
common
> > CFs. However this does not prevent a tenant from retrieving data
> belonging
> > to another tenant. For this to happen, we would need to have
separate CFs
> > and/or keyspaces for each tenant.
> > Looking for more information on the topic here
> >
>
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Re-Mult
i-tenancy-and-authentication-and-authorization-td5935230.htmland
> > other places, it looks like the recommendation is "not" to create
> > separate CFs and KSs for every tenant as this would have impacts on
> > Memtables and other memory issues. Does this recommendation still
hold
> > good?
> > With jiras like
> > https://issues.apache.org/jira/browse/CASSANDRA-2006resolved, does
it
> > mean we can now create multiple (but limited) CFs and KSs?
> > More generally, how do we prevent a tenant from
intentional/accidental
> data
> > manipulation of data owned by another tenant? (given that all
tenants
> will
> > provide the right credentials)
>
>

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