Hi, Thanks for working on this. This is an important piece of functionality to make Cassandra really viable for multi-tenancy.
I took a quick look at the proposal. It seems to be for hard cap rate limits without supporting burst usage and consumption of idle resources. This reduces efficiency quite a bit because it doesn't balance between tenants at saturation allowing them each to get some minimum with equal access to the remaining resources. The proposal also doesn't cover fairness and how we are ensuring that resources are fairly distributed when the rate limits are minimums (even if aspirational) rather than maximums and don't restrict tenants down to below the actual capacity of a node. QPS is not the only metric we need to track for fairness. CPU/IOPs and how much memory is used (and for how long!) are all factors, but for now maybe CPU/IOPs is the one to focus on. QPS still needs to be shared fairly because execution slots are not unlimited. A tenant with a small expensive queries shouldn't be able to dominate available resources. QPS itself is also problematic because time in the execution slot matters just as much how many times a second the client runs a query through an execution slot. Either way it's the time the slot is unavailable to other tenants that matters most. There are also background operations like compaction to consider. A cheap to write but expensive to compact data model can impact other tenants. We don't need to put absolutely everything under the scope of this single CEP, but I think anything that's in it should be a good fit for Cassandra and hard rate limits seems like something we should iterate on more. Ariel On Tue, Feb 24, 2026, at 4:47 AM, Justin Ling Mao wrote: > Hi everyone: > > I have created a JIRA ticket:**CASSANDRA-21158**, regarding a new feature: > Implementing quota management for multi-tenant. > You can find the design document here: > **https://docs.google.com/document/d/1BGDjBsuVkuISbN8lqxoZUuGbx0qRhuNA8BAxF48a24k** > If you are interested, please join the discussion. Once we’ve had a thorough > discussion and if the community finds this feature valuable, I will proceed > to create a CEP (Cassandra Enhancement Proposal) and subsequently submit a PR. > > Looking forward to your feedback! > > > -------------------------------- > Best regards > Justin Ling Mao > Beijing,China
