dbt-bigquery supports and enforces primary key constraints

[dbeatty10]

Previews

• Terms: Primary key - Data warehouse support for primary keys
• Model contracts: Platform constraint support

What are you changing in this pull request and why?

@bnaul called out here that some documentation isn't in alignment with the source code (which asserts that dbt-bigquery supports and enforces primary key constraints).

Here are some other docs that should all be in alignment, but aren't:

Model contracts: Platform constraint support

https://docs.getdbt.com/docs/collaborate/govern/model-contracts#platform-constraint-support

constraints: Platform-specific support

https://docs.getdbt.com/reference/resource-properties/constraints#platform-specific-support

Checklist

• Review the Content style guide and About versioning so my content adheres to these guidelines.
• I've checked that the preview renders correctly
• I've checked that that code behaves as described

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Name	Status	Preview	Comments	Updated (UTC)
docs-getdbt-com	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 16, 2023 3:19pm

[bnaul]

Primary (and foreign) keys are supported but not enforced in BQ, so I think you only want the first change

[dbeatty10]

Primary (and foreign) keys are supported but not enforced in BQ, so I think you only want the first change

Thank you!

Appreciate you pointing out that in BigQuery Key Constraints are not enforced and are only so the query optimizer may use this information to better optimize queries. As such, users will need to have testing in place to ensure primary key fields are unique and not null.

Our source code is currently asserting that they are enforced (?!), so I've reached out to our engineering team for clarification. Guessing that we'll want to update the source code to be this instead:

        ConstraintType.primary_key: ConstraintSupport.NOT_ENFORCED,
        ConstraintType.foreign_key: ConstraintSupport.NOT_ENFORCED,

Once that clarification comes in, will try to update all the different documentation pages and source code so that they are all in alignment.

[bnaul]

ah interesting, they most definitely are not 😅

[mirnawong1]

lgtm and preview looks right!