AWS Databases Flashcards
How can an existing RDS instance be encrypted?
AWS doesn’t support encrypting existing RDS instances - you would need to create a new encrypted instance and migrate your data to that
What is the difference between Read Replicas and Multi AZ Databases?
A Multi AZ Database is designed for disaster recovery (it provides a failover for an RDS instance to a different AWS Zone) while a Read Replica is designed for scaling.
Can an existing RDS database be encrypted?
No, encryption must be applied to databases at their creation. To get encryption on an existing database you must create a new encrypted database and migrate your existing data to that.
What does Multi-AZ provide?
Multi-AZ allows you to have an exact copy of your database in another availability zone. This is used for DR only, it will not improve performance.
What is a Read Replica database?
A Read Replica is a read-only copy of your database that is used to improve performance by scaling out in a high-read environment. A Read Replica can be converted to a primary database if it is required to write to it.
What is ElasticCache?
ElasticCache is a webservice that makes it easy to deploy, operate, and scale an in-memory cache in the cloud.
What services does ElasticCache support?
It supports Memcached and Redis.
What is the consistency model of Amazon DynamoDB?
When reading data from Amazon DynamoDB, users can specify whether they want the read to be eventually consistent or strongly consistent:
Eventually consistent reads (Default) – The eventual consistency option maximizes your read throughput. However, an eventually consistent read might not reflect the results of a recently completed write. Consistency across all copies of data is usually reached within a second. Repeating a read after a short time should return the updated data.
Strongly consistent reads — In addition to eventual consistency, Amazon DynamoDB also gives you the flexibility and control to request a strongly consistent read if your application, or an element of your application, requires it. A strongly consistent read returns a result that reflects all writes that received a successful response prior to the read.
What is Amazon DynamoDB?
Amazon DynamoDB is a fully managed NoSQL database service that provides fast and predictable performance with seamless scalability. DynamoDB enables customers to offload the administrative burdens of operating and scaling distributed databases to AWS so that they don’t have to worry about hardware provisioning, setup and configuration, throughput capacity planning, replication, software patching, or cluster scaling.
What is Amazon Redshift?
Amazon Redshift is a fast, fully managed data warehouse that makes it simple and cost-effective to analyze all your data using standard SQL and your existing Business Intelligence (BI) tools.
What does a leader node do? What does a compute node do?
In Redshift A leader node receives queries from client applications, parses the queries and develops execution plans, which are an ordered set of steps to process these queries. The leader node then coordinates the parallel execution of these plans with the compute nodes, aggregates the intermediate results from these nodes and finally returns the results back to the client applications.
Compute nodes execute the steps specified in the execution plans and transmit data among themselves to serve these queries. The intermediate results are sent back to the leader node for aggregation before being sent back to the client applications.
What is Amazon Aurora?
Amazon Aurora is a relational database engine that combines the speed and reliability of high-end commercial databases with the simplicity and cost-effectiveness of open source databases. Amazon Aurora MySQL delivers up to five times the performance of MySQL without requiring any changes to most MySQL applications; similarly, Amazon Aurora PostgreSQL delivers up to three times the performance of PostgreSQL.
If my Aurora database fails, what is my recovery path?
Amazon Aurora automatically maintains 6 copies of your data across 3 Availability Zones and will automatically attempt to recover your database in a healthy AZ with no data loss.
If you are using Amazon RDS Provisioned IOPS storage with MySQL and Oracle database engines what is the maximum size RDS volume you can have by default?
6TB
In RDS when using multiple availability zones, can you use the secondary database as an independent read node?
No
