Meltano

Constraints look very cool <https://docs.getdbt.com/reference/resource-properties/constraints>

And also:
&gt; Snowflake suppports four types of constraints: `unique`, `not null`, `primary key` and `foreign key`.
&gt; *It is important to note that only the `not null` (and the `not null` property of `primary key`) are actually checked today. There rest of the constraints are purely metadata, not verified when inserting data.*
&gt; Currently, Snowflake doesn't support the `check` syntax and dbt will skip the `check` config and raise a warning message if it is set on some models in the dbt project.
:slightly_smiling_face:

&gt; Redshift currently only enforces `not null` constraints; all other constraints are metadata only. Additionally, Redshift does not allow column checks at the time of table creation. See more in the Redshift documentation <https://docs.aws.amazon.com/redshift/latest/dg/t_Defining_constraints.html|here>.

&gt; BigQuery allows defining `not null` constraints. However, it does _not_ support or enforce the definition of unenforced constraints, such as `primary key`.

Ties into a conversation I was recently having with <@U06C5L36YDC>. Many big data platforms have dropped (real) support for uniqueness and foreign key constraints, due to the scaling limitations when applied to a platform that stores all table data in separate logical files/shards.

the "not null" constraints are only evaluated one row at a time, so won't present any scaling limitations. All the others do require some type of sort operation and/or cross-node communication.