Which constraint type is enforced in Snowflake from the ANSI SQL standard?
Which constraint type is enforced in Snowflake from the ANSI SQL standard?
In Snowflake, the NOT NULL constraint is enforced from the ANSI SQL standard. While Snowflake supports defining other constraint types like UNIQUE, PRIMARY KEY, and FOREIGN KEY, these are largely advisory and not enforced by the system. However, NOT NULL constraints are always enforced at the table level, ensuring that columns defined with this constraint cannot contain NULL values.
Snowflake supports defining and maintaining constraints, but does not enforce them, except for NOT NULL constraints, which are always enforced. https://docs.snowflake.com/en/sql-reference/constraints-overview.html
Correct. The reason is probably that NOT NULL is the only one that can be verified rapidly. Others need scanning data.
Verified