dbt-debugging

name	dbt-debugging
description	Load when dbt run or dbt parse fails. Covers YML duplicate patches, ref errors, passthrough model warnings, current_date fixes, DuckDB error messages, and zero-row diagnosis.
type	skill

dbt Debugging Skill

1. Duplicate YML Patches (VERY COMMON)

dbt fails with "Duplicate patch" when the same model appears in multiple YML files. Fix in ONE pass:

1. Glob models/**/*.yml to find all YML files
2. Keep the entry with the full contract (descriptions, refs, columns) — usually in a subdirectory YML
3. Remove the duplicate from schema.yml (which typically only has tests)

2. Ref Not Found

If Compilation Error: node not found for ref():

• Check if the name is a raw DuckDB table: SELECT table_name FROM information_schema.tables WHERE table_name = 'name'
• If yes, create an ephemeral stub:

  {{ config(materialized='ephemeral') }}
  select * from main.<name>
  

• If ephemeral causes CTE issues, replace {{ ref('name') }} with main.name directly

3. Passthrough Model Warning

NEVER create .sql files named after raw tables (e.g. circuits.sql, results.sql). This DESTROYS source data by replacing it with a materialized model. Fix: add schema: main to the source definition in YML instead.

4. current_date Fix

If dbt_project_map warns about current_date usage:

1. Call get_date_boundaries — find the column marked "USE THIS"
2. Replace current_date/now() with (SELECT MAX(<col>) FROM {{ ref('<table>') }})
3. For package models: create models/<name>.sql, paste full SQL, replace current_date

5. ROW_NUMBER Non-Determinism

If dbt_project_map warns about ROW_NUMBER/RANK:

1. Check if ORDER BY columns are unique within each partition
2. If not unique, append the primary key to ORDER BY
3. Re-run dbt run --select <model>

6. DuckDB Error Messages

Error	Fix
invalid date field format	STRPTIME(col, '%d/%m/%Y')::DATE
Table does not exist	Check actual names with describe_table
column not found	Check exact names — case matters in DuckDB
Cannot mix TIMESTAMP and INTEGER	Cast both args to same type
No function matches DOUBLE / VARCHAR	Add explicit CAST()
fivetran_utils is undefined	Run dbt deps (only if packages.yml exists)

7. Zero-Row Model

Binary search: comment out WHERE clauses and JOINs one at a time to find which condition drops all rows. Most common cause: INNER JOIN where LEFT JOIN is needed.

8. Fan-Out (Too Many Rows)

1. Diagnose: SELECT join_key, COUNT(*) FROM right_table GROUP BY 1 HAVING COUNT(*) > 1
2. Fix A: pre-aggregate right table before joining
3. Fix B: SELECT DISTINCT (if valid for the grain)
4. Fix C: ROW_NUMBER() dedup pattern