Informational foreign keys are available in Spanner. Informational foreign keys don't enforce referential integrity and are used to declare the intended logical data model for query optimization

## Feature Informational foreign keys are available in Spanner. Informational foreign keys don't enforce referential integrity and are used to declare the intended logical data model for query optimization. Enforced foreign keys, which enforce referential integrity, are also available. Informational foreign keys are supported by GoogleSQL only. Enforced foreign keys are supported by GoogleSQL and PostgreSQL. For more information, see the following: * [Types of foreign keys](https://cloud.google.com/spanner/docs/foreign-keys/overview#types-of-foreign-keys) * [Comparison of foreign key types](https://cloud.google.com/spanner/docs/foreign-keys/overview#comparison-of-foreign-keys-types) * [Choose which foreign key type to use](https://cloud.google.com/spanner/docs/foreign-keys/overview#choose-foreign-key-type) * [Use informational foreign keys](https://cloud.google.com/spanner/docs/foreign-keys/overview#use-informational-foreign-keys)