32 core processor machines are expensiveCosts go way up when you try to scale these databasesAlso-instability.
Terabytes of data~1,000,000 ops/secondSchema changes are difficult (impossible)Manual sharding takes a lot of effortAutomated sharding + replication is difficult
100 M users, 25 TB data
Horizontal – commodity hardware, not specialized boxes
Cluster is a logical storage ringNode placement divides the ring into ranges that represent start/stop points for keysAutomatic or manual token assignment (use another slide for that) Closer together means less responsibility and data
Hinting not designed for long failures.
RDBMS focus on consistency. Limits scale.
No multi-key transactions
Sstable proliferation degrades performance.
DistributedScalableSchema-freeSparse tableEventually consistentTunable (throughput and fault-tolerance)