TABLE_CONSTRAINTS view

The TABLE_CONSTRAINTS view contains the primary and foreign key relations in a BigQuery dataset.

Required permissions

You need the following Identity and Access Management (IAM) permissions:

  • bigquery.tables.get for viewing primary and foreign key definitions.
  • bigquery.tables.list for viewing table information schemas.

Each of the following predefined roles has the needed permissions to perform the workflows detailed in this document:

  • roles/bigquery.dataEditor
  • roles/bigquery.dataOwner
  • roles/bigquery.admin

For more information about IAM roles and permissions in BigQuery, see Predefined roles and permissions.

Schema

The INFORMATION_SCHEMA.TABLE_CONSTRAINTS view has the following schema:

Column Name Type Meaning

CONSTRAINT_CATALOG

STRING

The constraint project name.

CONSTRAINT_SCHEMA

STRING

The constraint dataset name.

CONSTRAINT_NAME

STRING

The constraint name.

TABLE_CATALOG

STRING

The constrained table project name.

TABLE_SCHEMA

STRING

The constrained table dataset name.

TABLE_NAME

STRING

The constrained table name.

CONSTRAINT_TYPE

STRING

Either PRIMARY KEY or FOREIGN KEY.

IS_DEFERRABLE

STRING

YES or NO depending on if a constraint is deferrable. Only NO is supported.

INITIALLY_DEFERRED

STRING

Only NO is supported.

ENFORCED

STRING

YES or NO depending on if the constraint is enforced.
Only NO is supported.

Scope and syntax

Queries against this view must include a dataset qualifier. For queries with a dataset qualifier, you must have permissions for the dataset. For more information see Syntax. The following table shows the region and resource scopes for this view:

View name Resource scope Region scope
[PROJECT_ID.]DATASET.INFORMATION_SCHEMA.TABLE_CONSTRAINTS; Dataset level Dataset location
Replace the following:
  • Optional: PROJECT_ID: the ID of your Google Cloud project. If not specified, the default project is used.

Examples

The following query shows the constraints for a single table in a dataset:

SELECT *
FROM PROJECT_ID.DATASET.INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE table_name = TABLE;

Replace the following:

  • PROJECT_ID: Optional. The name of your cloud project. If not specified, this command uses the default project.
  • DATASET: The name of your dataset.
  • TABLE: The name of the table.

Conversely, the following query shows the constraints for all tables in a single dataset.

SELECT *
FROM PROJECT_ID.DATASET.INFORMATION_SCHEMA.TABLE_CONSTRAINTS;

With existing constraints, the query results are similar to the following:

+-----+---------------------+-------------------+-----------------------+---------------------+--------------+------------+-----------------+---------------+--------------------+----------+
| Row | constraint_catalog  | constraint_schema |    constraint_name    |    table_catalog    | table_schema | table_name | constraint_type | is_deferrable | initially_deferred | enforced |
+-----+---------------------+-------------------+-----------------------+---------------------+--------------+------------+-----------------+---------------+--------------------+----------+
|   1 | myConstraintCatalog | myDataset         | orders.pk$            | myConstraintCatalog | myDataset    | orders     | PRIMARY KEY     | NO            | NO                 | NO       |
|   2 | myConstraintCatalog | myDataset         | orders.order_customer | myConstraintCatalog | myDataset    | orders     | FOREIGN KEY     | NO            | NO                 | NO       |
+-----+---------------------+-------------------+-----------------------+---------------------+--------------+------------+-----------------+---------------+--------------------+----------+

If the table or dataset has no constraints, the query results look like this:

+-----------------------------+
| There is no data to display |
+-----------------------------+