How do constraints, such as primary keys, impact table joins between parent/child tables in Snowflake?

Question

Options

• APrimary keys allow only one-to-one table joins
• BConstraints limit table join operations to specific data types
• CPrimary keys ensure data uniqueness for table relationships
• DConstraints restrict data access to authorized user roles

• B
  3% (1)
• C
  93% (27)
• D
  3% (1)

Explanation

Option C is correct because primary keys enforce uniqueness on a column (or set of columns), which is what makes meaningful parent/child relationships possible in joins - without uniqueness on the parent side, you cannot reliably identify which parent record a child belongs to. In Snowflake, constraints like primary and foreign keys are defined but not enforced at write time; however, they still serve as metadata that documents and enables optimizer hints for join relationships.

Why the distractors are wrong:

• A is wrong because primary keys say nothing about join cardinality - a parent row can join to many child rows (one-to-many is the norm).
• B is wrong because joins are not restricted by data types through constraints; type compatibility is a separate concern handled at the query level.
• D is wrong because access control in Snowflake is handled by roles and privileges (RBAC), not by constraints.

Memory tip: Think of a primary key as a name tag at a party - it uniquely identifies each guest (row), which is what lets you correctly match guests across two tables. Constraints = uniqueness = reliable relationships.

No community discussion yet for this question.