Yes, right now it's probably not technically possible, from a resource point of view, to run 4k keyspaces in a cassandra cluster.

Those management features you may have been able to do as meta data operations will prob become long running background tasks.


On 3 Sep 2010, at 21:28, Mike Peters <> wrote:

Very interesting. Thank you

So it sounds like other than being able to quickly truncate customer-keyspaces, with Cassandra there's no real benefit in keeping each customer data in a separate keyspace. 

We'll suffer on the memory side with all the switching between keyspaces and we're better off storing all customer data under the same keyspace?

On 9/2/2010 11:29 PM, Aaron Morton wrote:
Create one big happy love in keyspace. Use the key structure to identify the different clients data. 

The is more support for multi tenancy systems but a lot of the memory configuration is per keyspace/column family, so you cannot run that many keyspaces. 

This page has some more information


On 03 Sep, 2010,at 01:25 PM, Mike Peters <> wrote:


We're in the process of migrating 4,000 MySQL client databases to
Cassandra. All database schemas are identical.

With MySQL, we used to provision a separate 'database' per each client,
to make it easier to shard and move things around.

Does it make sense to migrate the 4,000 MySQL databases to 4,000
keyspaces in Cassandra? Or should we stick with a single keyspace?

My concerns are -
#1. Will every single node end up with 4k folders under /cassandra/data/?

#2. Performance: Will Cassandra work better with a single keyspace +
lots of keys, or thousands of keyspaces?


Granted it's 'cleaner' to have a separate keyspace per each client, but
maybe that's not the best approach with Cassandra.