A brief overview of AWS DBMS services

Amazon® Web Services® (AWS®) provides database (DB) services in both Database-as-a-Service (DBaaS) and Platform-as-a-Service (PaaS) models for both relational and non-relational databases.

These services are available for most of the license and open-source products provided by major service providers. AWS offers an efficient and cost-effective method to install and manage secure and scalable DBs at the enterprise level.

This post briefly introduces the AWS DBMS services and the features that make them very popular DBMS services for any cloud platform. We provide an introduction to the following AWS services:

• RDS: an RDBMS service
• Aurora: an in-house RDBMS service
• Dynamo DB: a non-relational service
• DMS: a DB migration service

 Amazon DBMS services

The following image shows DBMS types based on data organization:

AWS provides various licensed and freely available DB services to its users. These services fall under both the heads of relational and non-relational database services. Apart from providing DBMS engines from popular companies like Oracle®, and Microsoft®, Amazon provides an in-house DBMS service known as Aurora®, which is highly advanced, secure,and reliable. Besides providing a dedicated RDBMS service, AWS also provides Aurora services, a light, on-demand, and auto-scaling DBMS service.

 Amazon Relational Database Service

Some of the famous relational DB systems available in Amazon Relational Database Services (RDS) include  Aurora, PostgreSQ®, MySQL®;, MariaDB®, Oracle®, and so on.

RDS has the following features: 

• DBaaS (Database as a Service) used to provision a fully functional DB without admin overhead.
• Runs on virtual machines though you can't log in to these servers.
• AWS takes care of patching of RDS operating system (OS) and DB.
• RDS supports multiple DB engines, including MYSQL, MariaDB, PostgreSQL, Oracle, MS SQL  server, and Aurora.
• You can deploy RDS in one or many Availability Zones (AZ). 
• Many backup options are available, including automated on S3 and manual snapshots. 
• When you restore by using any backup, the restored DB is a brand-new instance.
• Resiliency using multiple AZs (primary and standby model ) provides synchronous replication and automatic failover without any intervention.
• You can do performance enhancement by using read replicas that provide asynchronous  replicas in read-only copies.
• Performance provided through a read replica.

Amazon Aurora

Amazon Aurora is an AWS  relational database service. As the Aurora User Guide  explains, "Aurora is part of the managed database service Amazon Relational Database Service (Amazon RDS). Amazon RDS is a web service that makes it easier to set up, operate, and scale a relational database in the cloud."

Following are some of the features of the Amazon Aurora DBMS service:

• "Amazon Aurora is a MySQL and PostgreSQL-compatible relational database built for the cloud, that combines the performance and availability of traditional enterprise databases with the simplicity and cost-effectiveness of open source databases." - (from Amazon Aura documentation.
• "Amazon Aurora is up to five times faster than standard MySQL databases and three times faster than standard PostgreSQL databases. It provides the security, availability, and reliability of commercial databases at 1/10th the cost."- (from Amazon Aura documentation).
• Uses the base configuration of a cluster. It contains a single primary instance and zero or more replicas.
• All instances use shared storage, known as cluster volumes, and are auto-healing. Cluster volumes scale automatically, and AWS bills you for only consumed space while constantly backing it up in S3.
• A minimum of three availability zones contain two copies of your data, with a minimum of three availability zones, so there are at least six copies of your data.
• Aurora storage heals itself by continuously scanning data blocks and disks and by automatically repairing errors.
• Up to 15 replicas are possible, which provide the facility of parallel query. 
• Read-write uses an endpoint, which balances connection across all replicas.

Aurora serverless

According to Using Amazon Aurora Serverless v1, Amazon Aurora Serverless "is an on-demand autoscaling configuration for Amazon Aurora. An Aurora Serverless DB cluster is a DB cluster that scales compute capacity up and down based on your application's needs. This contrasts with Aurora provisioned DB clusters, for which you manually manage capacity. Aurora Serverless provides a relatively simple, cost-effective option for infrequent, intermittent, or unpredictable workloads. It is cost-effective because it automatically starts up, scales compute capacity to match your application's usage, and shuts down when it's not in use."

Aurora Serverless features include the following ones: 

• It's based on the same DB engine as Aurora, but instead of provisioning hardware, AWS  handles it as service.
• You need to specify the maximum and minimum number of Aurora capacity Unit (ACU) in GB  of memory
• You can use a data API to query DB (like `toad`).
• It is charged on a per-second basis and can be paused during a time of inactivity with  only storage fees charged.
• It's ideal for a scenario where the usage pattern is unknown with a lightly used application and non-linear load.

Dynamo DB (No SQL)

DynamoDB has the following features: 

• "Amazon DynamoDB is a fast and flexible NoSQL database service for all applications that need consistent, single-digit millisecond latency at any scale. It is a fully managed database and supports both document and key-value data models. Its flexible data model and reliable performance make it a great fit for mobile, web, gaming, ad-tech, Internet of Things ( IoT), and many other applications." Important Amazon Cloud Services
• "Amazon DynamoDB is a key-value and document database that delivers single-digit millisecond performance at any scale. It's a fully managed, multi region, [durable] database with built-in security, backup and restore, and in-memory caching for internet-scale applications." an Amazon Database whitepaper
• DB service is partitioned regionally and allows the creation of a table.
• A table is a collection of items that share the same partition key and sort key with other configuration and performance settings.
• An item is a collection of attributes inside a table that shares the same key structure as every other item in the table.
• An attribute is a key and value.

The following example shows a table, "People", with three items that each have attributes: person id (primary key), last name, and so on:

         
*Image Sources :(https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.CoreComponents.html)[https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.CoreComponents.html]*                              

AWS Database Migration Service

The AWS Database Migration Service (DMS) is a database migration tool provided. The following
image shows the migration of data between services:

Image source

AWS Data Migration Systems (DMS) provides the following services:

• "Helps you migrate databases to AWS quickly and securely. The source database remains fully operational during the migration, minimizing downtime to applications that rely on the database." - (https://digitalcloud.training/certification-training/aws-solutions-architect-associate/migration/aws-database-migration-service/), (https://digitalcloud.training/certification-training/aws-solutions-architect-associate/migration/aws-database-migration-service/).
• Enables you to migrate your data into the AWS Cloud, between on-premises instances (through an AWS Cloud setup), or between combinations of cloud and on-premises setups.
• Supports migration to the same DB engine as well as different DB engines, both homogeneous and heterogeneous.
• "Creates the tables and associated primary keys if they don't exist on the target. You can pre-create the target tables [manually], or you can use AWS Schema Conversion Tool (SCT) to create some or all of the target tables, indexes, views, triggers, and so on."AWS Database Migration Service
• Does not require SCT if you are moving to the same DB engine.

Conclusion

DBMS services are an essential part of any organization, and we are in an age where data is said to be the new oil. While raw data might cause confusion, a suitable DBMS system helps users with transactions and provides insights into various information. But DBMS' are complicated systems that require dedicated infrastructure and a team with technical expertise because security and scalability are a big challenge.

AWS provides a wide range of enterprise-class DBMS engines that can cater to almost all use cases and budget constraints and excellent scalability, including fully and partially managed options. You also have the option of database backup, which you can customize as needed and use AWS DMS to simplify database migration. Hence, for any new enterprises and especially startups with budget constraints, AWS provides a perfect environment to cater to requirements. Big, legacy customers also realize the potential of AWS database services and are slowly but steadily moving toward it.