Note_Tech

All technological notes.

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AWS - RDS

Relational Database Service (RDS)
- a relational database service that supports multiple SQL engines. Relational is synonymous with SQL and Online Transactional Processing (OLTP).
- Supported SQL Engine
It allows you to create databases in the cloud that are managed by AWS
- Postgres
- MySQL
- MariaDB
- Oracle
- Microsoft SQL Server
- Aurora (AWS Proprietary database)
Advantage over using RDS versus deploying DB on EC2
- RDS is a managed service:
  - Automated provisioning, OS patching
  - Continuous backups and restore to specific timestamp (Point in Time Restore)!
  - Monitoring dashboards
  - Read replicas for improved read performance
  - Multi AZ setup for DR (Disaster Recovery)
  - Maintenance windows for upgrades
  - Scaling capability (vertical and horizontal)
  - Storage backed by EBS (gp2 or io1)
- BUT you can’t SSH into your instances
RDS on VMware
- allow to deploy RDS supported engines to an on-premise data-center.
- For users who want databases managed by RDS on user’s own datacenter.

Aurora
- an “AWS-implementation” of PostgreSQL / MySQL
- PostgreSQL and MySQL are both supported as Aurora DB
- For users who want a relational database for Postgres or MySQL.
Aurora is “AWS cloud optimized” and claims 5x performance improvement over MySQL on RDS, over 3x the performance of Postgres on RDS
Aurora storage automatically grows in increments of 10GB, up to 128 TB
Aurora costs more than RDS (20% more) – but is more efficient
Not in the free tier
Aurora Severless
- the serverless on-demand version of Aurora.
- For users who want most of the benefits of Aurora but can trade to have cold-starts or don’t have lots of traffic demand.

The same way RDS is to get managed Relational Databases…
ElastiCache is to get managed Redis or Memcached
Caches are in-memory databases with high performance, low latency
Helps reduce load off databases for read intensive workloads
AWS takes care of OS maintenance / patching, optimizations, setup, configuration, monitoring, failure recovery and backups