AWS – RDS – Exam Tips

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Know what a relational database is. A relational database consists of one or more tables. Communication to and from relational databases usually involves simple SQL queries, such as “Add a new record,” or “What is the cost of product x?” These simple queries are often referred to as OLTP.

Understand which databases are supported by Amazon RDS. Amazon RDS currently supports six relational database engines:

  • Microsoft SQL Server

  • MySQL Server

  • Oracle

  • PostgreSQL

  • MariaDB

  • Amazon Aurora

Understand the operational benefits of using Amazon RDS. Amazon RDS is a managed service provided by AWS. AWS is responsible for patching, antivirus, and management of the underlying guest OS for Amazon RDS. Amazon RDS greatly simplifies the process of setting a secondary slave with replication for failover and setting up read replicas to offload queries.

Remember that you cannot access the underlying OS for Amazon RDS DB instances. You cannot use Remote Desktop Protocol (RDP) or SSH to connect to the underlying OS. If you need to access the OS, install custom software or agents, or want to use a database engine not supported by Amazon RDS, consider running your database on Amazon EC2 instead.

Know that you can increase availability using Amazon RDS Multi-AZ deployment. Add fault tolerance to your Amazon RDS database using Multi-AZ deployment. You can quickly set up a secondary DB Instance in another Availability Zone with Multi-AZ for rapid failover.

Understand the importance of RPO and RTO. Each application should set RPO and RTO targets to define the amount of acceptable data loss and also the amount of time required to recover from an incident. Amazon RDS can be used to meet a wide range of RPO and RTO requirements.

Understand that Amazon RDS handles Multi-AZ failover for you. If your primary Amazon RDS Instance becomes unavailable, AWS fails over to your secondary instance in another Availability Zone automatically. This failover is done by pointing your existing database endpoint to a new IP address. You do not have to change the connection string manually; AWS handles the DNS change automatically.

Remember that Amazon RDS read replicas are used for scaling out and increased performance. This replication feature makes it easy to scale out your read-intensive databases. Read replicas are currently supported in Amazon RDS for MySQL, PostgreSQL, and Amazon Aurora. You can create one or more replicas of a database within a single AWS Region or across multiple AWS Regions. Amazon RDS uses native replication to propagate changes made to a source DB Instance to any associated read replicas. Amazon RDS also supports cross-region read replicas to replicate changes asynchronously to another geography or AWS Region.

Know what a NoSQL database is. NoSQL databases are non-relational databases, meaning that you do not have to have an existing table created in which to store your data. NoSQL databases come in the following formats:

  • Document databases

  • Graph stores

  • Key/value stores

  • Wide-column stores

Remember that Amazon DynamoDB is AWS NoSQL service. You should remember that for NoSQL databases, AWS provides a fully managed service called Amazon DynamoDB. Amazon DynamoDB is an extremely fast NoSQL database with predictable performance and high scalability. You can use Amazon DynamoDB to create a table that can store and retrieve any amount of data and serve any level of request traffic. Amazon DynamoDB automatically spreads the data and traffic for the table over a sufficient number of partitions to handle the request capacity specified by the customer and the amount of data stored, while maintaining consistent and fast performance.

Know what a data warehouse is. A data warehouse is a central repository for data that can come from one or more sources. This data repository would be used for query and analysis using OLAP. An organization’s management typically uses a data warehouse to compile reports on specific data. Data warehouses are usually queried with highly complex queries.

Remember that Amazon Redshift is AWS data warehouse service. You should remember that Amazon Redshift is Amazon’s data warehouse service. Amazon Redshift organizes the data by column instead of storing data as a series of rows. Because only the columns involved in the queries are processed and columnar data is stored sequentially on the storage media, column-based systems require far fewer I/Os, which greatly improves query performance. Another advantage of columnar data storage is the increased compression, which can further reduce overall I/O.

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