Q1. What is the difference between a Dedicated SQL Pool and Serverless SQL Pool in Azure Synapse?
A Dedicated SQL Pool (formerly SQL DW) provisions reserved compute and storage capacity upfront, making it ideal for predictable, high-concurrency production workloads where you need consistent query performance. A Serverless SQL Pool, on the other hand, is a consumption-based model with no infrastructure to manage -- you query data directly from Azure Data Lake Storage using T-SQL, and you pay per terabyte processed. I use Serverless for ad-hoc exploration and cost-effective data lake queries, while Dedicated handles our mission-critical reporting pipelines.
Q2. What is a Columnstore Index and why does Azure Synapse use it?
A Columnstore Index stores data column-by-column rather than row-by-row, which dramatically improves compression and analytical query performance because only the relevant columns are scanned. In Azure Synapse, all tables in a Dedicated SQL Pool use Clustered Columnstore Indexes (CCI) by default. For a typical analytical query reading only 5 of 50 columns, CCI reduces IO by up to 90%, which directly translates to faster dashboards and lower cost.