How Snowflake’s RELY Constraint Supercharges Your Star‑Schema Queries

Snowflake's RELY constraint is an underutilized metadata hint that signals the optimizer to trust primary and foreign key relationships, enabling it to eliminate redundant joins in star-schema queries. When RELY is set on both the primary key of a dimension table and the foreign key of a fact table, Snowflake can skip scanning tables that contribute no columns beyond the join key itself, resulting in faster query performance and potential cost savings through smaller warehouse usage.