Database, Analytics, ML Flashcards
What is RDS backed by?
EBS
What happens when you are running out of provisioned space on an RDS database?
AWS will automatically scale it for you
If you want to limit how much your DB in RDS can hold, what can you do?
Set the Maximum Storage Threshold
How many read replicas can you have in RDS?
5
True or False: RDS Read Replicas in the same region do not pay the network fee
True. Data transfer to read replicas in other AZs have to pay a networking fee
Why would we use RDS Multi AZ?
It is primarily used for disaster recovery. It performs synchronous replication to read instances
True or False: We cannot set our read replicas in Multi AZ for Disaster Recovery DBs
False. We can set our Read Replicas for DR
What is RDS Custom?
RDS Custom allows us to use Oracle and SQL Server with OS and database customization. We can access the underlying EC2 instance, which RDS managed DB don’t allow us to do
What is an Aurora Writer Endpoint?
A pointer that points to the Master. If the Master fails, and a Replica DB is promoted, the Writer Endpoint automatically shifts to the new Master.
Therefore we do not have to change out apps endpoint
What is an Aurora Reader Endpoint?
It is a pointer that points to a Load Balancer that sits in front of all the replica DBs to perform consistent and fault tolerant reads
We want to run intensive queries on certain Aurora DB instances that have stronger underlying infra. What can we do?
Create a Custom Endpoint. Custom Endpoints allow us to target specific Read Replicas for different types of operations or needs
What is Aurora Serverless?
It allows us to hand off the instantiation and scaling to AWS. It uses a fleet of DBs provisioned by AWS to hold our data. We do not have to pay for upfront capacity
What is Aurora Multi-Master?
Every DB Instance is a Read/Write node. If one fails, you can still write to other Master instances. You may have to configure conflict avoidance strategy, like implementing health checks to see if a Writer instance is still available. Great for if you need high write capacity
What is Global Aurora?
Your DB spans multiple regions, with up to 16 DB Read Instances in each. In one region you have your read/write DB, and up to five read-only secondary regions.
If one entire region fails, it will quickly shift read/write capabilities to another region
Cross-region replication takes less than one second
What two machine learning services can Aurora integrate with?
SageMaker - Deploy machine learning models
Comprehend - Uses machine learning to learn insights and connections in text
True or False: RDS Automated backups don’t expire but manual DB Snapshots do
False. Automated backups last for 1 to 35 days, manual DB snapshots don’t expire unless deleted
If you stop an RDS DB for a long while, what is the recommended protocol?
Create a snapshot, delete the DB and then restore from snapshot when needing the DB. Stopped RDS instances still charge for storage
What is Aurora Database Cloning?
Aurora DB cloning allows us to create a new Aurora DB Cluster from an existing one. It is faster than a snapshot & restore
What is an RDS Proxy?
RDS Proxy sits in front of the RDS instance and pools together all the connections.
This can be beneficial as it puts less strain on the RDS instance resources (CPU, RAM) and minimizes connection timeoutes
True or False: The RDS proxy is available to the public
False, It is only available with the VPC
What two DB engines can we choose from with Aurora?
Postgres and MySQL
What AWS resource can we sit in front of RDS to take the load off of our DB resources?
We can use ElastiCache, which will handle caching (note: our applications will still have to implement our Caching strategy)
We want to have Multi-AZ with Auto-Failover and read replicas for our caching, would we use Redis or Memcached?
Redis
https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/WhatIs.html#WhatIs.Overview
True or False: ElastiCache supports IAM authentication for Redis and Memcached
False, it only supports it for Redis
Which service supports SASL-based authentication?
Memcached
What is Redis AUTH?
It allows you to create a password/token when creating the cluster; that password or token is then used to start making operations against Redis. Also allows for SSL in-flight encryption
What are the three cache patterns for ElastiCache?
Lazy Loading: Application checks for data in cache, if the data is not in cache it retrieves it from the database and then writes it to cache
Write-Through: All the write data is written to cache
Session Store: store temporary data in cache using TTL feature
These three are not mutually exclusive
You’re planning for a new solution that requires a MySQL database that must be available even in case of a disaster in one of the Availability Zones. What should you use?
Enable Multi-AZ
You have set up read replicas on your RDS database, but users are complaining that upon updating their social media posts, they do not see their updated posts right away. What is a possible cause for this?
Read Replicas have async replication, therefore it’s likely your users will miss the most up-to-date info because of eventual consistency
Which RDS (NOT Aurora) feature when used does not require you to change the SQL connection string: Multi-AZ or Read Replicas?
Multi-AZ, keeps the same connection string regardless of which database is up
An analytics application is currently performing its queries against your main production RDS database. These queries run at any time of the day and slow down the RDS database which impacts your users’ experience. What should you do to improve the users’ experience?
Setup read replicas. This will take the load off the main production DB
You would like to ensure you have a replica of your database available in another AWS Region if a disaster happens to your main AWS Region. Which database do you recommend to implement this easily?
Aurora Global Database. Multi-AZ won’t work because that is an AZ and not a region