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ScyllaDB Cluster

NoSQL database with DynamoDB-compatible API (Alternator).

Overview

Property Value
Namespace scylla
Type ScyllaCluster CRD
Layer Database (Layer 4)
Dependencies Scylla Operator
Access http://scylla.local (Alternator API)

Purpose

ScyllaDB provides a high-performance NoSQL database with a DynamoDB-compatible API, ideal for chat history, session storage, and high-throughput workloads.

Features

  • Alternator API - DynamoDB-compatible interface
  • High Performance - Discord-proven at trillion+ message scale
  • Native TTL - Automatic data expiration
  • Linear Scalability - Add nodes for more capacity
  • Low Latency - Sub-millisecond response times

Use Cases

Use Case Why ScyllaDB
Chat History High write throughput, TTL for retention
Session Storage Low latency, automatic expiration
Time-series Efficient range queries, compaction
Caching Persistent cache with TTL

Architecture

graph TB
    subgraph Applications
        App[Application]
    end

    subgraph ScyllaDB
        N1[Scylla Node 1]
        N2[Scylla Node 2]
        N3[Scylla Node 3]
    end

    subgraph API
        ALT[Alternator<br/>DynamoDB API]
        CQL[CQL<br/>Native API]
    end

    App -->|DynamoDB SDK| ALT
    App -->|CQL Driver| CQL
    ALT --> N1
    ALT --> N2
    ALT --> N3
    CQL --> N1
    CQL --> N2
    CQL --> N3

Access

Alternator (DynamoDB API)

http://scylla.local

kubectl port-forward -n scylla svc/scylla-client 8000:8000

Using AWS SDK

import boto3

dynamodb = boto3.resource(
    'dynamodb',
    endpoint_url='http://scylla.local',
    region_name='us-east-1',
    aws_access_key_id='none',
    aws_secret_access_key='none'
)

# Create table
table = dynamodb.create_table(
    TableName='messages',
    KeySchema=[
        {'AttributeName': 'pk', 'KeyType': 'HASH'},
        {'AttributeName': 'sk', 'KeyType': 'RANGE'}
    ],
    AttributeDefinitions=[
        {'AttributeName': 'pk', 'AttributeType': 'S'},
        {'AttributeName': 'sk', 'AttributeType': 'S'}
    ],
    BillingMode='PAY_PER_REQUEST'
)

CQL (Native)

# Connect via cqlsh
kubectl exec -it scylla-dc-default-0 -n scylla -- cqlsh

TTL Configuration

Enable TTL on a table:

# DynamoDB API
dynamodb.meta.client.update_time_to_live(
    TableName='messages',
    TimeToLiveSpecification={
        'Enabled': True,
        'AttributeName': 'ttl'
    }
)

Verification

# Check cluster status
kubectl get scyllacluster -n scylla

# Describe cluster
kubectl describe scyllacluster scylla -n scylla

# Check pods
kubectl get pods -n scylla

# Test Alternator endpoint
curl http://scylla.local/

Troubleshooting

Cluster not forming

# Check operator logs
kubectl logs -n scylla-operator deploy/scylla-operator

# Check scylla pod logs
kubectl logs -n scylla scylla-dc-default-0

Alternator not responding

# Check Alternator is enabled
kubectl describe scyllacluster scylla -n scylla | grep -i alternator

# Check service
kubectl get svc -n scylla

Node not joining

  1. Check resource availability
  2. Verify network connectivity
  3. Check for scheduling issues
kubectl describe pod -n scylla <pod-name>