Scalability of Cassandra refers primarily to number of rows and number of nodes - to add more data, add more nodes.
Column families? As opposed to tables? Are you using Thrift instead of CQL3? You should be focusing on the latter, not the former. But either way, the general guidance is that there is no absolute limit of tables per se, but "low hundreds" is the recommended limit, regardless of whether how many key spaces they may be divided between. More than that is an anti-pattern for Cassandra - maybe you can make it work for your application, but it isn't recommended. A successful Cassandra deployment is critically dependent on careful data modeling - who is responsible for modeling each of these tables, you and a single, tightly-knit team with very common interests and very specific goals and SLAs or many different developers with different managers with different goals such as SLAs? When you say multi-tenant, are you simply saying that each of your organization's customers has their data segregated, or does each customer have direct access to the cluster? -- Jack Krupansky On Tue, May 26, 2015 at 11:32 PM, Arun Chaitanya <chaitan64a...@gmail.com> wrote: > Good Day Everyone, > > I am very happy with the (almost) linear scalability offered by C*. We had > a lot of problems with RDBMS. > > But, I heard that C* has a limit on number of column families that can be > created in a single cluster. > The reason being each CF stores 1-2 MB on the JVM heap. > > In our use case, we have about 10000+ CF and we want to support > multi-tenancy. > (i.e 10000 * no of tenants) > > We are new to C* and being from RDBMS background, I would like to > understand how to tackle this scenario from your advice. > > Our plan is to use Off-Heap memtable approach. > http://www.datastax.com/dev/blog/off-heap-memtables-in-Cassandra-2-1 > > Each node in the cluster has following configuration > 16 GB machine (8GB Cassandra JVM + 2GB System + 6GB Off-Heap) > IMO, this should be able to support 1000 CF with no(very less) impact on > performance and startup time. > > We tackle multi-tenancy using different keyspaces.(Solution I found on the > web) > > Using this approach we can have 10 clusters doing the job. (We actually > are worried about the cost) > > Can you please help us evaluate this strategy? I want to hear communities > opinion on this. > > My major concerns being, > > 1. Is Off-Heap strategy safe and my assumption of 16 GB supporting 1000 CF > right? > > 2. Can we use multiple keyspaces to solve multi-tenancy? IMO, the number > of column families increase even when we use multiple keyspace. > > 3. I understand the complexity using multi-cluster for single application. > The code base will get tightly coupled with infrastructure. Is this the > right approach? > > Any suggestion is appreciated. > > Thanks, > Arun >
