Databases Flashcards
What are the 6 databases available in RDS?
- PostreSQL
- MS SQL Server
- Oracle
- MariaDB
- MySQL
- AWS Aurora (MySQL / PostgreSQL Emulation)
What happens in an AWS outage assuming you have a standby database? Is manual intervention required?
- AWS changes the CNAME from primary to backup DB
- Intervention is not needed
What is the use case for setting up multi-AZ database? What can you not to against the backup database in another region?
- Failover and/or Disaster recovery (Not to scale the performance)
- You cant run queries against the backup database
What are the variations on RDS read replicas?
- Standard
- Multi-AZ
Are read replicas Asynchronous or Synchronous
- Asynchronous
Can a read replica be promoted to be a primary database? What implications are there?
Yes, but it breaks the replication.
What is the main use case for read replicas?
- Scaling (for read heavy loads) not Disaster Recovery
What must be enabled to create read replicas?
Automatic backup
How many read replicas can you have on an RDS DB
5
Which database management systems can Aurora emulate?
- PostreSQL
- MySQL
How big is an Aurora DB? By how much does it scale? What is the max size?
- 10GB to start
- Increases automatically in 10GB increments
- Up to 128TB
How many vCPUs can Aurora use? How much RAM can it use?
- up to 96vcpus
- up to 768 GB of RAM
How many copies of your data are kept when using AWS Aurora
- 2 Per AZ
- Minimum of 3 AZ
- Minimum 6 copies
How many copies of data in an aurora database can be lost not affecting performance?
2
What types of replicas are available with Aurora? How many Read replicas are available for each?
- Aurora - 15 RRs
- Aurora MySQL - 5 RR
- Aurora PostgreSQL - 5 RR
How do aurora backups work?
- Aurora is automatically backed up with no impact to performance.
- Database snapshots can be taken, with no performance impact, these snapshots can be shared with other accounts.
Whats the use case for AWS Aurora Serverless?
- Great for spikey or unpredicatable workloads
- Only scales on when needed.
- Scales up and down as needed
How is Dynamo DB Stored?
- SSD Storage
- Spread across 3 datacenters (AZs)
- Encrypted at rest
What is DAX
- Dynamo DB Accelerator, managed, highly available in-memory cache
- Decreases request time to microseconds
- Developers don’t need to manage it - App speaks directly to DAX
- 10x performance improvement
How is Dynamo DB secured?
- Encrypted at rest
- Accessed via policies and roles
What are DynamoDB streams?
- Time ordered flow of transactions from DynamoDB
- Has its own endpoint
- up to 24 hours of retention
What are use cases for Dynamo DB transactions?
- Financial transactions
- Gaming
What about Dynamo DB backup and recovery?
- Can enable backups in the same region. they don’t impact performance.
- Point in time recovery is available but must be enabled.
What is a use case for using Dynamo DB Global Tables?
What technology in DynamoDB is required to use this?
- Replicating data from one table to another in real-time
- Globally distributed applications
- Global Tables is based on DynamoDB streams.
