add is_incremental as additional example of when you will need to force dependencies

[graciegoheen]

Contributions

• I have read the contribution docs, and understand what's expected of me.

Link to the page on docs.getdbt.com requiring updates

https://docs.getdbt.com/reference/dbt-jinja-functions/ref#forcing-dependencies

What part(s) of the page would you like to see updated?

We already have an example for when you need to force dependencies - a model that only has a macro.

Let's also add an example for when references are wrapped in the is_incremental() macro - see slack thread.

Dependencies nested in the is_incremental macro will not show up in lineage, so will need to force dependencies in that case.

Example

If you have an incremental model that includes a snippet like below, then you will not be able to see the source('raw', 'orders') upstream dependency in the lineage.

{% if is_incremental() %}
select * from {{ source('raw', 'orders') }}
{% endif %}

This is because the is_incremental macro will always return false at parse time, so anything buried inside that will not be available to parsing, so will not be added to depends_on.

So in this case, you'd need to do force a dependency outside of the is_incremental() conditional like this instead:

 -- depends_on: {{ source('raw', 'orders') }}

{% if is_incremental() %}
select * from {{ source('raw', 'orders') }}
{% endif %}

[runleonarun]

Thanks @graciegoheen! Anything you think we should add to the is_incremental macro docs?

[graciegoheen]

No I think this is enough!