Database Specialty - Amazon Keyspaces

Question 1

Amazon Keyspaces – Overview

Answer 1

• A scalable, highly available, and fully-managed database service
• Lets you run your Cassandra workloads on AWS
• Cassandra is an open-source, wide-column, NoSQL data store
• Is serverless, so you pay for what you use + autoscaling
• Supports thousands of requests per second with virtually unlimited throughput and storage
• Compatible with the CQL (Cassandra Query Language) API
• Security through IAM, VPC and KMS
• Data is encrypted by default, supports encryption at rest and in transit
• Supports continuous backups with PITR
• All writes replicated three times across multiple AZs for durability and availability
• Offers 99.99% availability SLA within Region with no scheduled downtime
• Monitoring through CloudWatch, DDL actions logged with CloudTrail
• Use cases: IoT device metadata / User profiles / Time-series data / Transactions data (e.g. ecommerce)

Question 2

CQL (Cassandra Query Language )

Answer 2

• You use CQL for interacting with Cassandra database
  (and with Keyspaces)
• To run CQL queries, you can use:
  • CQL editor in the AWS Console
  • cqlsh client (CQL shell)
  • Cassandra client driver (programmatic access)

Question 3

Migrating from Cassandra to Keyspaces

Answer 3

• Export existing cluster data to CSV files
• Import using cqlsh COPY command

Question 4

Read and write consistency in Keyspaces

Answer 4

• Two read consistency modes:
  
  • LOCAL_ONE consistency
  • LOCAL_QUORUM consistency
• LOCAL_ONE optimizes for performance and availability by returning
  the first returned value from any storage replica
• LOCAL_QUORUM optimizes for data correctness by requiring at least
  two replicas to return a value before it is returned to your application
• All writes use LOCAL_QUORUM for durability

Question 5

Keyspaces pricing - On-demand mode

Answer 5

• Uses RRUs and WRUs (read/write request units)
• You pay for the actual reads and writes
• Use with unpredictable application traffic
• 1 RRU = one 4KB read with LOCAL_QUORUM consistency
• 1 RRU = two 4KB reads with LOCAL_ONE consistency
• 1 WRU = one1KB write with LOCAL_QUORUM consistency

Question 6

Keyspaces pricing - Provisioned mode

Answer 6

• Uses RCUs and WCUs (read/write capacity units)
• You specify the number of reads and writes per second
• Lets you optimize costs if you have predictable application traffic and can forecast capacity requirements in advance
• 1 RCU = one 4KB read with LOCAL_QUORUM consistency
• 1 RCU = two 4KB reads with LOCAL_ONE consistency
• 1 WCU = one1KB write with LOCAL_QUORUM consistency