Amazon Aurora

• Aurora is a proprietary technology from AWS (not open sourced)
• Postgress and MYSQL are both supported as Aurora DB (that means your drivers will work as if Aurora was a Postgres or MYSQL database)
• Aurora is “AWS cloud optimized” and claims5x performance improvement over MySQL on RDS, over 3x the performance of Postgres on RDS
• Aurora storage automatically grows in increements of 10GB, up to 128 T B.
• Aurora have 15 replicas while MYSQL has 5, and the replication process is faster (sub 10ms replica lag)
• Failover in Aurora is instantaneous. It’s HA (high Avaiability) native.
• Aurora costs more than RDS** (20% more)** - but is more efficient

Aurora High Availability and read scaling

• 6 copies of your data across 3 AZ:
  • 4 copies out of 6 needed for writes
  • 3 copies out of 6 need for reads
  • Self healing with peer to peer replication
  • Storage is striped across 100s of volumes
• One Aurora instance takes write (master)
• Automated failover for master in less than 30 seconds
• Master + up to 15 Aurora read replicas serve reads
• Support for Cross Region Replication
• Shared storage Volume Replication + self healing + auto expanding

Aurora DB Cluster

• Write endpoint
  • Pointing to the master
• Reader Endpoint
  • Connection Load Balancing

Features of Aurora

• Automatic Failover
• Backup annd Recovery
• Isolation and security
• Industry compliance
• Push-button scaling
• Automated Patching with Zero Downtime
• Advanced Monitoring
• Routine Maintenance
• Backtrack: restore data at anypoint of time without using backups

Aurora Security

• Similar to RDS because uses the same engies
• Encryption at rest using KMS
• Automated backups, snapshots and replicas are also encrypted
• Encryption in flight using SSL (same proccess as MYSQL or Postgres)
• Possibility to autheticate usig IAM token (same method as RDS)
• You are responsible for protecting the instance with security groups
• You can’t SSH

Aurora Repliccas - Auto Scaling

• Write endpoint
• Many request to Reader endpoint and edpoint extended above replicas auto sccaling policies and shared storage volume

Aurora - Custom Endpoints

• Define a subset of Aurora Instannces as a Custom endpoint
• Example: Run analytical queries on specific replicas
• The reader Endpoint is generally not used after defining custom endpoints

Aurora Serverless

• Automated database instantiation and auto scaling based on actual usage
• Good for infrequent, intermittent or unpredictable workloads
• No capacity plannig needed
• Pay per second, can be most cost-effective
• Proxy fleet is managed by Aurora

Aurora Multi-Master

• In case you want immediate failover for write node (HA)
• Every node does R/W - vs promoting a RR as the new master

Global Aurora

• Aurora cross region read replicas
  • Usefule for disaster recovery
  • Simple to put in place
• Aurora Global Database (recommended):
  • 1 primary region (read / write)
  • Up to 5 secodary (read only) regions, replication lag is less than 1 second
  • Up to 16 read repliccas per secondary region
  • Helps for decreasing latency
  • Promotig another region (for disater recovery) has an RTO of < 1 minute

Aurora Machine Learning

• Enables you to add ML-based predictions to your applications via SQL
• Simple, optimized and secure integration between Aurora and AWS ML services
• Supported services
  • Amazon SageMaker (use with any ML model)
  • Amazon Comprehend (for sentiment analysis)
• You don’t need to have ML experience
• Use cases: fraud detection, ads targeting, sentiment analysis, product recommendations

Amazon ElastiCache Overview

• The same way RDS is to get managed Relational Databases…
• ElastiCache is to get managed Redis or Memcached
• Caches are in-memory databases with really high performance, low latency
• Helps reduce load off of databases for read intensive workloads
• Helps make your application stateless
• AWS takes care of OS maintanance / patching, optimizations, setup, configuration, monitoring, failure recovery and backups
• Using ElastiCache involves heavy application code changes

ElastiCache Solution Architecture - DB Cache

• Applications queries Elasticacche, if not available, get from RDS and store in ElastiCache
• Helps relieve load in RDS
• Cache must have an invalidation strategy to make sure only the most current data is used in there.

ElastiCache Solution Architecture - User Session Store

• User logs into any of the application
• The application writes the session data into ElastiCache
• The user hits another instance of our application
• The instance retrieves the data ans the user is already logged in
• The user retrieve session from ElastiCache

Elasticache: Redis vs Memcached

• Redis:
  • Multi AZ with Auto Failover
  • Read replicas to scale read and have availability
  • Data durability using AOF persistence
  • Backup and restore features
• Memcached
  • Multi-node for pariniong of data (sharding)
  • No high availability (replicationn)
  • Non persistent
  • No Backup and restore
  • Multi threaded architedture

ElastiCache - Cache Security

• All caches in ElastiCache
  • Do not support IAM authentication
  • IAM policies on ElastiCache are only used for AWS API-level security
• Redis AUTH
  • You can set a “password/token” when you ccreate a Redis cluster
  • This is an extra level of security for your cache (on top of security groups)
  • Support SSL in flight encryptionn
• Memcached
  • Supports SASL-based authentication (advanced)

Patterns for ElastiCache

• Lazy Loading: all the read data is cached, data can become state in cache
• Write Through: Adds or update data in the cache when written to a DB (no scale data)
• Session Store: store temporary session data in a cache (using TTL features)
• Qoute: There are only two hard things in Computer Science: cache invalidation and naming things

ElastiCache - Redis Use Case

• Gaming leadeerboards are coomputationally complex
• Redis Sorted sets guarantee both uniqueness and element ordering
• Each time a new elemennt added, it’s ranked in real time, then added in correct order

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