My Cassandra Summit 2015 presentation introducing Scylla, an open source NoSQL implementation compatible with Apache Cassandra, but 10 times faster. De-animated http://scylladb.com

1. Cloudius Systems presents:

2. 1,000,000 CQL operations
per server
Avi Kivity, CTO @ ScyllaDB
Cassandra Summit 2015

3. Capable of 1,000,000 operations per second
PER NODE
With predictable, low latencies
Compatible with Apache Cassandra
Scylla: A new NoSQL Database

4. THE POWER OF
CASSANDRA AT
THE SPEED OF REDIS
SCYLLA DB

5. THROUGHPUT

6. LATENCY

7. FULLY COMPATIBLE
❏ Uses Cassandra SSTables
❏ Use your existing drivers
❏ Use your existing CQL queries
❏ Use your existing cassandra.yaml
❏ Manage with nodetool or other JMX console
❏ Use your existing code with no change
❏ Copy over a complete Cassandra database
❏ Works with the Cassandra ecosystem (Spark etc.)

8. FULLY COMPATIBLE

9. WHAT WOULD YOU DO WITH 1 MILLION TPS?
Shrink your cluster by a factor of 10X
Handle 10X traffic spikes on Black Friday
Model your data instead of using Cassandra as K/V
Get the most out of your data - Run more queries
Maintain your clusters while serving
Stop using caches in front of the database

10. TECHNOLOGY:
HOW IT WORKS

11. SCYLLA IS QUITE DIFFERENT
Shard-per-core, no locks, no threads, zero-copy
Based on the Seastar C++ application framework
Efficient, unified DB cache (not using Linux page cache)
CQL-oriented storage engine
Exploit all hardware resources - NUMA, multiqueue NICs, etc

12. SCYLLA DB: ARCHITECTURE COMPARISON
Kernel
Cassandra
TCP/IPScheduler
queuequeuequeuequeuequeue
threads
NIC
Queues
Kernel
Traditional stack Scylla sharded stack
Memory
Lock contention
Cache contention
NUMA unfriendly
Application
TCP/IP
Task Scheduler
queuequeuequeuequeuequeuesmp queue
NIC
Queue
DPDK
Kernel
(isn’t
involved)
Userspace
Application
TCP/IP
Task Scheduler
queuequeuequeuequeuequeuesmp queue
NIC
Queue
DPDK
Kernel
(isn’t
involved)
Userspace
Application
TCP/IP
Task Scheduler
queuequeuequeuequeuequeuesmp queue
NIC
Queue
DPDK
Kernel
(isn’t
involved)
Userspace
Core
Database
TCP/IP
Task Scheduler
queuequeuequeuequeuequeuesmp queue
NIC
Queue
DPDK
Kernel
(isn’t
involved)
Userspace
No contention
Linear scaling
NUMA friendly

13. Scylla has its own task scheduler
Traditional stack Scylla stack
Promise
Task
Promise
Task
Promise
Task
Promise
Task
CPU
Promise
Task
Promise
Task
Promise
Task
Promise
Task
CPU
Promise
Task
Promise
Task
Promise
Task
Promise
Task
CPU
Promise
Task
Promise
Task
Promise
Task
Promise
Task
CPU
Promise
Task
Promise
Task
Promise
Task
Promise
Task
CPU
Promise is a
pointer to
eventually
computed value
Task is a pointer
to a lambda
function
Scheduler
CPU
Scheduler
CPU
Scheduler
CPU
Scheduler
CPU
Scheduler
CPU
Thread
Stack
Thread
Stack
Thread
Stack
Thread
Stack
Thread
Stack
Thread
Stack
Thread
Stack
Thread
Stack
Thread is a
function pointer
Stack is a byte
array from 64k to
megabytes
Context switch cost is
high. Large stacks pollutes
the caches No sharing, millions of
parallel events

14. Scylla Memory Management

15. Blasting out I/O operations
future<>
make_data_requests(digest_resolver_ptr resolver, targets_iterator begin,
targets_iterator end) {
return parallel_for_each(begin, end, [this, resolver =
std::move(resolver)] (gms::inet_address ep) {
return make_data_request(ep).then_wrapped([resolver, ep]
(future<foreign_ptr<lw_shared_ptr<query::result>>> f) {
try {
resolver->add_data(ep, f.get0());
} catch (...) {
resolver->error(ep, std::current_exception());
}
});
});
}

16. Unified cache
Cassandra Scylla
Key cache
Row cache
On-heap /
Off-heap
Linux page cache
SSTables
Unified cache
SSTables

17. Unified cache
Cassandra Scylla
Key cache
Row cache
On-heap /
Off-heap
Linux page cache
SSTables
Unified cache
SSTables
Tuning
Caching unparsed data
Parasitic rows
Page faults

18. ❏ Implement missing CQL features
❏ Stabilize clustering
❏ Complete nodetool support
❏ Spark integration, other connectors
❏ Thrift support
❏ Authentication and encryption
Work in progress

19. ❏ Open source @ github
❏ In Beta
❏ Try it out! RPM, Docker images available
❏ Live Demo @ ScyllaDB booth!
❏ → http://scylladb.com
OUTLOOK

20. ❏ Multi-tenancy
❏ New protocols (redis, …)
❏ Vertical integration (solr, …)
FUTURE

21. SCYLLA, NoSQL GOES NATIVE
Thank you.
http://scylladb.com