[CT-3309] --empty flag to to provide a cost-effective way to run a selection of empty models for dbt build and run

[graciegoheen]

Housekeeping

• I am a maintainer of dbt-core

Short description

introduce a new --empty flag, similar to this prototype for —sample to dbt run and dbt build

• when enabled, build/run model with each input having a limit 0 where false added to it → no data scan to build an empty version of the model in the WH!
• --empty works with --deferral for the dry-est of runs:
  - modified models are still built in dry-run mode (their refs use limit 0)
  - unmodified models are skipped?
  -similar to whats been proposed here: Schema-only dry-run feature - similar to a universal override of `materialize: view` or `LIMIT 0` #6989
• additional considerations:
  - how does this work for seeds?

Acceptance criteria

see description

Impact to Other Teams

Will backports be required?

none

Context

No response

[colin-rogers-dbt]

what if instead of a --empty flag we had a flag like --model-limit that accepted an integer input that we pass to a limit clause

[graciegoheen]

@colin-rogers-dbt we've done a lot of thinking about that!

@MichelleArk actually attempted this not to long ago:

• draft PR
• issue

but ran into enough complexities, that we decided it would be best to start with an --empty flag, which we could potentially extend for "sampling" in the future

would welcome your thoughts on the --sample issue :)

[FishtownBuildBot]

Opened a new issue in dbt-labs/docs.getdbt.com: dbt-labs/docs.getdbt.com#6131