When it comes to choosing between Azure SQL Database (SQL DB) and Azure SQL Data Warehouse (SQL DW), it’s important to understand their differences and use cases. While both can be used for building a data warehouse, SQL DB is designed for Online Transaction Processing (OLTP) applications, while SQL DW is strictly for Online Analytical Processing (OLAP) and data warehousing.
Here are some key differences between SQL DB and SQL DW:
Database Size
SQL DB has a limit of a 1TB database size. If you have a database that exceeds this limit, you will need to use sharding or cross-database queries with row-level security. On the other hand, SQL DW has no database size limit, making it easier to handle larger databases.
Performance
SQL DW is a Massively Parallel Processing (MPP) solution, which means queries can be significantly faster compared to SQL DB, which is a Symmetric Multi-Processing (SMP) solution.
Scalability
Both SQL DB and SQL DW can be easily scaled without any downtime. However, SQL DW offers more flexibility and ease of scaling, allowing you to scale compute independently from storage. SQL DW also provides a slider bar to increase or decrease performance, while SQL DB has a set number of service tiers to choose from.
Concurrency
SQL DB can support up to 6,400 concurrent queries and 32,000 active connections, making it a better choice for applications with a large number of users. On the other hand, SQL DW can only support up to 32 concurrent queries and 1,024 active connections.
Features
SQL DB supports features such as active geo-replication, in-memory OLTP, cross-database queries, and always encrypted data. However, SQL DW does not support these features. Instead, SQL DW offers features like Polybase, which allows you to query data from external sources.
Migration
Migrating schema from an on-premises SMP solution to SQL DW may have some challenges, such as handling foreign keys and primary keys. It’s important to consider these challenges when planning a migration. For more information on migrating your schema to SQL Data Warehouse, refer to the relevant documentation.
In conclusion, when choosing between Azure SQL Database and Azure SQL Data Warehouse, consider the specific requirements of your application. If you need OLTP capabilities and a smaller database size, SQL DB is the right choice. However, if you require OLAP capabilities, unlimited database size, and faster query performance, SQL DW is the better option.
For more information on SQL DB and SQL DW, check out my other blog posts on these topics.