Cross-dataset foreign key relationships in BigQuery

UpdatedMarch 2, 2026

•1 min read

Senior Data Engineer • Contractor / Freelancer • GCP & AWS Certified

It turns out you can now (don't know since when though) create cross-dataset foreign key relationships in BigQuery hashtag#SQL. Previously this was only possible for tables that are in the same dataset (but there were workarounds).

While the performance gain when using these unenforced PK/FK constraints in general may be up for discussion, it's definitely nice to be able to see this table metadata there, including the table grain 👍

For a refresher on what these constraints are, see my previous post.

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