does dbt-loom solve upstream dependencies only?

[eshetben]

hi :)
i have a question about the general concept of dbt-loom
(didn't find a fitting channel on the dbt slack 😊 )

would it be accurate to say that the cross-project dependency supported by dbt-loom is one directional? in the sense that the parent project will not be aware that the child project is refencing it?
for example - given project A (data warehouse) and project B (data mart),
project B will utilize dbt-loom to reference project A, but project A will not be aware of that connection, right?

i'm looking at this from the perspective of the one who maintains the parent project (A) - how to prevent from breaking the child project(s)? how to gain visibility into downstream dependencies on other projects?
i guess what i'm asking is - how can i test changes made on project A without knowing if it's being referenced in other projects?

thanks

[nicholasyager]

Hey @eshetben! Thanks for reaching out.

It is 100% accurate to say that the cross-project referencing support enabled by dbt-loom is one-directional. Public models are assumed to be public to any valid downstream consumer at a dbt-core level.

In order to have a full view of the multi-project lineage, one would need to have an external system that incorporates information from all downstream projects. This information could then be used to construct lineage at a project level. dbt Cloud currently enables this, as do other dbt-core hosting services w/ multi-project support. A scrappy engineer might also be able to piece the lineage together if their projects have a consistent method for storing/distributing project artifacts.

how can i test changes made on project A without knowing if it's being referenced in other projects?

This is an excellent question! I am of the opinion that one can go a long way by using model contracts, model versions, and unit tests to confirm/govern their project's functionality and structure. The dbt-meshify tool will likely be your friend if you choose to go that route.

[eshetben]

thanks @nicholasyager for that quick and informative reply!
i'll give meshify a go