How do you handle cross-source joins safely in Foundry?

• A. Rely on ad hoc join keys without contracts.
• B. Rely on manual checks after joins are executed.
• C. Use standardized schemas, data contracts, and join keys; ensure lineage and quality controls.
• D. Avoid documenting lineage during joins.

Answer: (C)

Cross-source joins are safest when you establish a consistent, contract-driven understanding of the data you’re combining. In Foundry this means using standardized schemas and data contracts that codify the expected fields, types, and semantics for each source, so the join operation isn’t guessing at identifiers or behavior as data evolves. You also define stable join keys and how they map across sources, ensuring alignment even as source systems change. Enforcing quality controls before the join helps catch issues early—bad records or mismatched data types won’t corrupt downstream results. Documenting lineage provides visibility into where data originated and how it was transformed, enabling accurate impact analysis, auditing, and reproducibility. Together, these practices create a repeatable, auditable, and safer cross-source joining process. Relying on ad hoc join keys, post-join manual checks, or skipping lineage would introduce drift and governance gaps, making results harder to trust.