How to add a check constraint in sql azure data warehouse? I'd like to add a check constraint to a table in azure data warehouse. 

I have the below script:

alter table [FactTbl_Test] add constraint Ck_Test_id check ([Test_Id] != 'Unknown')


This causes the below error:


  Parse error at line: 2, column: 74: Incorrect syntax near 'check'.


Edit:

Also appears to fail with the same error if the constraint is created inside the table declaration.
This and constraints in general are currently unsupported in Azure SQL Data Warehouse. See https://docs.microsoft.com/en-us/azure/sql-data-warehouse/sql-data-warehouse-tables-overview#unsupported-table-features for full list.

If the constraint is not enforced at the source or if you have multiple sources, you can implement during the ETL or ELT process. For small datasets, ETL would probably work better. With large datasets, you're likely to get better performance via ELT-L. As in extract then load to a temp table (heap is fast), perform the check/cleansing then load to the final table.