Compare database services in AWS and Azure
Databases underpin most internet and intranet applications and cloud services offer various types.
In your global clothing retailer, you have systems that store both relational data in Amazon Relational Database Service (RDS) and NoSQL data in DynamoDB SimpleDB and Amazon DocumentDB. In the recently acquired company, which uses Azure for cloud systems, data is stored in Azure SQL Database, Azure Database for MariaDB, and in Azure Cosmos DB. You need to investigate the capabilities of all these systems to determine which can be merged and which migrated.
In this unit, you compare database services offered by Amazon Web Services (AWS) and Azure.
Understand database technologies on Azure and AWS
Relational databases enforce strict relationships between data rows in different tables and a static schema. NoSQL databases are less strict but can store data more efficiently and are more effective for some applications. Data warehouses are amalgamations of databases from throughout your organizations, designed to provide deep insights and support. Both Azure and AWS provide options for all these data stores and more.
Let's explore how AWS data services map to similar offerings in Azure:
Relational databases
In AWS, RDS is a managed relational database service that supports six database engines: Amazon Aurora, PostgreSQL, MySQL, MariaDB, Oracle Database, and SQL Server.
In Azure, instead of a single relational database service with six engines, you have separate services:
- Azure SQL Database: A full cloud-based implementation of Microsoft's industry-leading SQL Server database system.
- Azure Database for MySQL: A full cloud-based implementation of Oracle's MySQL database server.
- Azure Database for MariaDB: MariaDB is a fork of MySQL, guaranteed to remain free and open source after Oracle's acquisition of MySQL.
- Azure Database for PostgreSQL: A full cloud-based implementation of the popular PostgreSQL database server.
NoSQL databases
In AWS, there are three NoSQL services to choose from:
- DynamoDB SimpleDB
- Amazon DocumentDB
- Amazon Neptune(Graph)
In Azure, the Cosmos DB service has a semi-structured design and supports many different data APIs including:
- NoSQL
- MongoDB
- PostgreSQL
- Cassandra
- Gremlin (Graph)
- Azure Storage Tables API
NoSQL is the native API and you should choose it if you're building a solution from scratch. However, if you want to migrate a system from a MongoDB database, use the MongoDB API to reduce the amount of recoding you have to complete.
Data warehouses
In AWS, the Amazon Redshift system provides data warehousing functionality. The Azure equivalent is Azure Synapse Analytics.
Serverless data services
In serverless computing, a cloud service automatically scales compute resources to reflect demand. In certain usage scenarios, this approach can reduce costs for services that sometimes have low traffic:
- Azure SQL Database: Use the Serverless compute tier to implement this functionality.
- AWS Aurora: Use the AWS Aurora Serverless service to implement this functionality.
Other database services
Caching databases are popular ways to optimize performance for cloud-native applications and often use Redis. Azure Cache for Redis is an implementation of Redis in the Azure cloud. The equivalent service in AWS is Amazon MemoryDB for Redis. Another non-Redis cache service is ElastiCache.
There are various big data, analytics, and ETL/ELT services in Azure including: Azure Databricks, Azure HDInsight, and Azure Data Factory. Similar functionality is available in AWS with Amazon Elastic MapReduce (EMR). Amazon Athena is also used for querying data in S3 using SQL.
Database migration
The Azure Database Migration Service is a tool that helps you move data, schema, and database objects to Azure. You can migrate from AWS database to Microsoft SQL Server, MySQL, PostreSQL, and MongoDB.
| Source | Target | Offline support | Online support |
|---|---|---|---|
| Amazon RDS SQL | Azure SQL Database | Yes | No |
| Amazon RDS SQL | Azure SQL Database Managed Instance | Yes | Yes |
| Amazon RDS SQL | Azure SQL Virtual Machine (VM) | Yes | Yes |
| Amazon RDS SQL | Azure Database for MySQL - Single server | Yes | No |
| Amazon RDS SQL | Azure Database for MySQL - Flexible server | Yes | Yes |
| Amazon RDS MySQL | Azure Database for MySQL - Flexible server | Yes | Yes |
| Amazon RDS PostgreSQL | Database for MySQL - Flexible server | No | Yes |
Offline support for migrating databases from AWS includes Amazon RDS SQL Server, Amazon RDS MySQL, and Amazon RDS PostgreSQL. This type of migration is a one-time transfer from the source platform to the target platform. The database is offline from the time that the migration starts to when it completes.
Online support for migrating databases from AWS includes Amazon RDS SQL, Amazon RDS MySQL, and Amazon RDS PostgreSQL. This type of migration provides support for continually synchronizing a database from the source platform to the target platform. An online migration has minimal downtime.
For an up to date list of source and target database migrations that the Azure Database Migration Service supports, see Azure Database Migration Service supported scenarios.