Migrating from SQL Server to Snowflake: Handling Collation and Constraints
As organizations modernize their data platforms, migrating from on-premise SQL Server to Snowflake is a common step toward scalability and cloud-native analytics. While the process seems straightforward, two critical aspects often create challenges: collation and constraints. Ignoring these can lead to data integrity issues, inconsistent query results, and costly rework.
Looking at key conversion considerations here https://medium.com/@snowflakewiki/sql-server-to-snowflake-a-practical-migration-blueprint-4255fc9350ae, we’ll focus on top two factors that can significantly impact migrations — collation and constraints and explore how to handle them effectively.
Why Collation Matters in Migration
SQL Server typically uses Case-Insensitive (CI) collation by default, whereas Snowflake defaults to Case-Sensitive (CS). This difference impacts:
- Joins and Filters: Queries relying on case-insensitive matching may fail or return inconsistent results.
- Search Behavior: User experience changes when case sensitivity is introduced unexpectedly.
- ETL Logic: Legacy scripts may break if not adapted.
Recommended Collation Strategies
Constraints: The Silent Risk
Snowflake supports PRIMARY KEY, FOREIGN KEY, and UNIQUE constraints — but only as metadata. They are not enforced. This creates risks like:
- Duplicate Records
- Orphaned Rows
- Referential Integrity Gaps
Constraint Enforcement Strategies
Best Practices for a Smooth Migration
- Adopt Collation Governance: Use metadata-driven tracking for exceptions.
- Automate Constraint Checks: Integrate with CI/CD pipelines for consistency.
- Validate Early and Often: Build a “Golden Validation Pack” for parity and drift detection.
- Monitor Continuously: Implement unified monitoring across ETL and Snowflake.
Key Takeaways
- Collation and constraints are not just technical details — they impact data integrity and user experience.
- A hybrid approach for both ensures compatibility, performance, and governance.
- Plan these strategies upfront to avoid costly rework and ensure a successful migration.
References:
Get Snowflake Wiki’s stories in your inbox
Join Medium for free to get updates from this writer.
https://docs.snowflake.com/en/sql-reference/collation
https://docs.snowflake.com/en/sql-reference/constraints
Follow and Clap if you like the content and feel free to ask if you have any questions in the comments. I will be more than happy to assist and guide you.
