[Bug] The --empty flag produces broken SQL when code has {{ref...}}or {{source..}} with an alias

[siljamardla]

Is this a new bug in dbt-core?

• I believe this is a new bug in dbt-core
• I have searched the existing issues, and I could not find an existing issue for this bug

Current Behavior

If you have a dbt model that uses the {{ref...}}or {{source..}} macro together with an alias, for example:

select * from {{ ref("dim_car") }} as cars 

and you try to run it with the --empty flag then the compiled SQL will have double aliasing, resulting in broken SQL

Expected Behavior

The alias should not be changed as to not alter the script

Steps To Reproduce

Create a dbt model with a {{ref...}} macro and try to compile its code with the --empty flag.

Relevant log output

No response

Environment

- OS: macOS
- Python: 3.11
- dbt: 1.8

Which database adapter are you using with dbt?

spark

Additional Context

There are 2 workarounds.

1. Write all your dbt models with CTEs so that there are no aliases right after the macros, something like

with cars as (
    select * from {{ ref("dim_car") }}
)
… 

2. Update the BaseRelation class to have require_alias be False by default. It's in the .venv/lib/python3.11/site-packages/dbt/adapters/base/relation.py file, line 51

[dbeatty10]

Thanks for reporting this @siljamardla !

To align with the corresponding solutions for dbt-bigquery, dbt-snowflake, dbt-redshift, etc, I think the solution would be to add require_alias: bool = False here rather than changing the default value here.

Here are some reference implementations:

• dbt-labs/dbt-bigquery@49d6c1e
• dbt-labs/dbt-snowflake@0153bd0
• dbt-labs/dbt-bigquery@49d6c1e

[anaghshineh]

Hey, @dbeatty10! Hope you're well. I recently changed jobs and am going to be working more heavily with the Spark adapter (and less so the BigQuery one!). Hit this issue last week when trying to run --empty. Adopted the approach you outlined above. Hope to see this integrated soon, so my team can take advantage of dry runs as part of CI!