Databases Flashcards
What are the 6 relationship database (OLTP) flavors on AWS?
- SQL Server
- Oracle
- MySQL
- PostgreSQL
- Amazon Aurora
- MariaDB
What are the two key features for RDS in AWS?
- Multi-AZ - for disaster recovery
- Read Replicas - for performance
What is the difference between multi-az and read replica?
Use multi az when you want to have a secondary database that will allow for immediate failover.
User read replica if you need to scale out reads for your material. You need to manually set different ec2 instances to read from each replica, there is no failover that is done automatically.
What is the primary difference between relational and nonrelational databases? What is amazons solution for nonrelational databases?
In non relational databases you can have any number of columns per row.
DynamoDB
What is data warehousing?
Used for business intelligence. Pull in large and complex datasets for analytics.
What is Online Transaction Process (OLTP) vs Online Analytics Processing (OLAP)?
OLTP is mostly for reads on data from databases.
OLAP is mostly aggregation / analyzing of data from databases.
What is Amazon’s data warehouse solution (for OLAP) called?
Redshift
What is ElastiCache?
Web service that makes it easy to deploy, operate, and scale an in-memory cache in the cloud. Improves performance of web applications by allowing you to retrieve information from fast, managed in-memory caches instead of relying entirely on slower disk-based databases.
What is the difference between Redshift and ElastiCache?
Redshift is used for business intelligence or data warehousing. ElastiCache is to speed up performance of existing databases (frequently identical queries).
What are the two different types of methods for backups on RDS?
- Automated backups
- Database snapshots
What are automated backups?
allow you to recover the database to any point in time recovery within the “retention period”.
Where is the snapshot stored?
Within s3.
True or False. Database snapshots are stored manually.
True. They are user-initiated.
What is encryption at rest?
Encryption is done using the AWS key management service. The data stored at rest in the underlying storage is encrypted as are backups, read replicas, and database snapshots.
Can you SSH into your RDS instance?
No, you cannot log onto the RDS instance. It runs on virtual machines (even if you can’t see it, Amazon can). RDS is not serverless (Aurora is the exception to the rule).
What is Dynamo DB?
A fast and flexible NoSQL database service for all applications that need consistent, isngle-digit millisecond latency at any scale. It is a fully managed database and supports both document and key-value data models.
List the 4 basics of DynamoDB.
- Stored on SSD storage
- Spread across 3 geographically distinct data centers
- Eventual Consistent Reads (default)
- Strongly Consistent reads
What is eventual consistent reads vs strongly consistent reads?
Eventual consistency reads is consistency across all copies of data is usually reached within a second.
Strong Consistent reads - returns a result that reflects all writes that are received a successful response prior to reading (< a second).
What is Redshift?
a fast and powerful, fully managed, petabyte-scale data warehouse service in the cloud.
What are the various configurations you can have for Redshift? 2 types.
- single node (160 gb)
- multi-node
- leader node (manages client connections and receives queries)
- compute node (store data and perform queries and computations. Up to 128 compute nodes
How much are you charged for leader node hours?
Nothing. Only charged for compute node hours.
True or False. Redshift is only available in one AZ.
True.
True or False. Redshift always attempts to maintain at least 5 copies of your data.
False. Redshift always attempts to maintain at least 3 copies of your data (the original and replica on the compute nodes and a backup in Amazon s3.)
True or False. Redshift can also asynchronously replicate your snapshots to s3 in another region for disaster recovery.
True.
What is Aurora?
MySQL and PostgreSQL compatible relational database engine that combines the speed and availability of high-end commercial databases with the simplicity and cost-effectiveness of open source databases.
True or False. Aurora provides up to five times better performance than MySQL and three times better than PostgreSQL databases at a much lower price point, whilst delivering similar performance and availability.
True.
What does Aurora start with in terms of storage? What increments does it scale with?
10 GB and scales in 10 GB increment up to 64 TB.
What can the compute resources for Aurroa scale up to?
32 vCPUs and 244 GB of memory.
What kind of redudancy does Aurora provide?
2 copies of your data is contained in each availability zone, with a minimum of 3 availability zones. 6 copies of your data.
What is Aurora serverless?
On-demand, autoscaling configuration for the MySQL-compatible and PostgreSQL-compatible editions of Amazon Aurora. Automatically starts up, shuts down and scales capacity up or down based on your application’s needs.
What are the requirement(s) for read replicas?
must have backups turned on
What are the different qualities of read replicas? List 6
- they can be multi-az
- used to increase performance
- must have backups turned on
- can be in different regions
- can be MySQL, PostgreSQL, MariaDB Oracle, Aurora
- can be promoted to master, this will break the read replica
What are the features for Multi AZ? List 2.
- built mostly for failover (disaster recovery)
- can force a failover from one AZ to another by rebooting the RDS instance
What is ElastiCache?
A web service that makes it easy to deploy, operate, and scale an in-memory cache in the cloud. Used to increase database and web application performance.