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ScyllaDB is a high-performance NoSQL database, reimagined from Apache Cassandra but built in C++ for better efficiency. Discord migrated trillions of messages from Cassandra to ScyllaDB, achieving significant improvements in latency, scalability, and operational efficiency.
Key Architecture
- Shard-per-Core: Each CPU core has a dedicated data partition and memory.
- Seastar Framework: A C++ asynchronous framework with zero-copy networking.
- Storage: Uses in-memory memtables and immutable SSTables on disk.
- Consensus: Optimized Paxos for consistency across replicas.
- Communication: Gossip protocol for cluster coordination.
Discord’s Challenge
- 177 Cassandra nodes storing trillions of messages.
- Hot partitions causing 40-125ms p99 read latency.
- Unpredictable performance during traffic spikes.
Migration Results
- Nodes: Reduced from 177 to 72 (60% reduction).
- Read Latency: Dropped from 40-125ms to 15ms p99.
- Write Latency: Reduced from 5-70ms to 5ms p99.
- Storage: 9TB per node (2x capacity).
- Migration Time: Completed in 9 days using a custom Rust tool.
Key Benefits
- No garbage collection issues (unlike Java-based Cassandra).
- Linear scalability with core count.
- Full CQL compatibility for easy migration.
- Eliminated operational firefights.
You Should Know:
Commands & Tools for Database Migration & Optimization
Linux Performance Monitoring
Check CPU and memory usage top htop vmstat 1 Disk I/O monitoring iostat -x 1 Network traffic iftop -n Check latency between nodes ping <node-ip> mtr <node-ip>
ScyllaDB & Cassandra Commands
Start ScyllaDB sudo systemctl start scylla-server Check cluster status nodetool status CQL shell for ScyllaDB/Cassandra cqlsh Flush memtables to SSTables nodetool flush Repair nodes nodetool repair
Benchmarking Tools
Stress testing with cassandra-stress cassandra-stress write n=1000000 -rate threads=50 ScyllaDB-specific benchmarks scylla-bench -workload=uniform -mode=write -replication-factor=3 -nodes=<ip-list>
Rust Migration Tool (Example)
use scylla::{Session, SessionBuilder};
use std::error::Error;
[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
let session: Session = SessionBuilder::new()
.known_node("127.0.0.1:9042")
.build()
.await?;
session
.query("INSERT INTO keyspace.table (id, data) VALUES (?, ?)", (1, "migrated_data"))
.await?;
Ok(())
}
What Undercode Say:
Discord’s migration to ScyllaDB demonstrates the power of optimized database architectures in handling large-scale data efficiently. By leveraging C++ and a shard-per-core model, ScyllaDB eliminates Java’s garbage collection overhead, ensuring predictable performance.
For engineers managing high-traffic databases, consider:
- Sharding strategies to avoid hot partitions.
- Asynchronous frameworks (like Seastar) for high throughput.
- Benchmarking before migration to avoid downtime.
Expected Output:
- Nodes reduced by 60%
- Read latency improved by 4x
- Consistent write performance under load
- Successful migration in 9 days
Prediction:
As more companies face scalability challenges with traditional NoSQL databases, migrations to optimized alternatives like ScyllaDB will increase, especially for real-time messaging and IoT applications. Expect more Rust-based migration tools to emerge.
IT/Security Reporter URL:
Reported By: Curiouslearner Discord – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
