[Core] Update docs on dbt-databricks constraints

[togobingi]

Link to the page(s) on docs.getdbt.com requiring updates

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

Tell us more about this update

The docs says: "As Databricks does not support transactions nor allows using create or replace table with a column schema, the table is first created without a schema, and alter statements are then executed to add the different constraints."

However, you can create and replace tables with a column schema as shown in the Databricks docs: https://docs.databricks.com/en/tables/constraints.html#set-a-not-null-constraint-in-databricks

Implementing this approach would allow dbt to enforce constraints in Databricks by ensuring 'bad' data never gets inserted into the tables in the first place, which isn't exactly possible now.

Reviewers/Stakeholders/SMEs

@mirnawong1

Related GitHub issues

No response

Additional information

No response

[mirnawong1]

thanks for opening this up @togobingi and appreciate the detailed description! I'm verifying internally and will get back to you here!

[mirnawong1]

hey @togobingi , thanks so much for opening this issue up! can you say more about how you came to this conclusion? I've just checked internally with the team and it looks like dbt-databricks doesn't currently support create/replace table with constraints, but it's on the backlog as a high priority.

if you can clarify, i can work with the team to understand this more. many thanks!