RDS + Aurora + ElastiCache Flashcards
What does RDS stand for?
Relational Database Service
Which databases are supported by RDS?
Postgres, MySQL, MariaDB, Oracle, MS SQL Server, IBM DB2, Aurora
What are advantages of RDS over EC2-deployed databases?
Managed service with provisioning, backups, scaling, monitoring, but no SSH access.
What is RDS Storage Auto Scaling?
Automatically increases storage when free space drops below 10%.
What is the difference between RDS Read Replicas and Multi-AZ?
Read Replicas improve read scalability; Multi-AZ improves disaster recovery.
How many Read Replicas can RDS have?
Up to 15.
Are RDS Read Replicas synchronous?
No, replication is asynchronous.
What is Amazon Aurora?
AWS-optimized database compatible with MySQL and Postgres, high performance and high availability.
How many replicas does Aurora support?
Up to 15 with sub-10ms replica lag.
How does Aurora handle failover?
Instantaneous failover, 6 copies across 3 AZs.
What is Aurora Backtrack?
Restore data to a previous point without using backups.
How is RDS/Aurora encrypted at rest?
Using AWS KMS keys defined at launch.
How is RDS/Aurora encrypted in-flight?
Using TLS.
What is IAM Authentication in RDS?
Use IAM roles to authenticate instead of username/password.
What is RDS Proxy?
Managed proxy to pool DB connections and improve failover time.
Which engines does RDS Proxy support?
RDS & Aurora for MySQL, PostgreSQL, MariaDB, MS SQL Server.
What is ElastiCache?
Managed in-memory cache service for Redis or Memcached.
What is the main benefit of using ElastiCache?
Reduce database load and improve application performance.
How does ElastiCache help with user sessions?
Stores user session data in-memory for quick access across app instances.
Redis vs Memcached: which supports replication?
Redis supports replication and durability; Memcached does not.
Which ElastiCache engine supports backup/restore?
Redis.
What is Lazy Loading in caching?
Only loads data into cache on request, reducing unused data.
What is Write-Through caching?
Updates cache immediately on DB write.
What are the main cache eviction strategies?
Explicit delete, LRU eviction, TTL expiration.
What is TTL in caching?
Time-To-Live: how long data stays in cache before expiration.
When should you use Lazy Loading?
When reads are frequent and data doesn’t change often.
What is Amazon MemoryDB?
Redis-compatible, durable in-memory DB with high throughput and multi-AZ support.
