Dedicated vs serverless pools - difference and performance

Question

I am working with dedicated pools in Azure Synapse, but never had a concrete understanding when to use them and when to use the serverless pools. What is the difference between them in terms of performance and what are the best practices ?

Answer 1

Hello WeirdMan !

Thank you for posting on Microsoft Learn.

I am summarizing the differences between Dedicated SQL Pools and Serverless SQL Pools in Azure Synapse Analytics, including their performance characteristics, use cases, and best practices—summarized in a table format:

Aspect	Dedicated SQL Pool	Serverless SQL Pool
Provisioning	Requires explicit resource provisioning (DWUs)	On-demand, no provisioning needed
Provisioning	Requires explicit resource provisioning (DWUs)	On-demand, no provisioning needed
Billing	Billed per hour based on DWU, regardless of usage	Billed per TB of data processed
Performance	High performance for large, complex workloads	Suitable for ad-hoc, lightweight, or infrequent queries
Scalability	Manually scalable (DWU scaling or pause/resume)	Auto-scales behind the scenes
Data Storage	Stores data in dedicated distributed tables (example CCI)	Queries external data (e.g., in Data Lake using OPENROWSET)
Latency	Lower latency for repeated queries on large data volumes	Higher latency for large data scans or repeated queries
Data Source	Data stored in dedicated SQL pool tables	External data in ADLS Gen2, Cosmos DB, etc.
Use Cases	- Large ETL workloads- Complex joins/aggregations- High concurrency- Data warehousing	- Data exploration- Quick dashboards- ELT validation- Cost-efficient ad-hoc analytics
Optimization Options	Distribution, partitioning, indexing, materialized views	Limited optimization; best practices include filtering early
Concurrency	Higher concurrency with proper scaling	Limited by backend resources; good for smaller user base
Security & Governance	Advanced RBAC, auditing, managed VNET	Supports RBAC; less granular control compared to dedicated

https://learn.microsoft.com/en-us/azure/synapse-analytics/sql/best-practices-dedicated-sql-pool

https://learn.microsoft.com/en-us/azure/synapse-analytics/sql/best-practices-serverless-sql-pool