Migrating Dbt Core To Fusion

Migrating a dbt Core Project to Fusion

dbt Fusion is dbt Labs' next-generation engine for parsing, compiling, and running dbt projects. This skill guides you through migrating an existing dbt Core project to be compatible with the Fusion engine.

Goals

1. Make a pre-existing dbt project compatible with dbt Fusion, so it can parse and compile successfully on the Fusion engine.
2. Preserve existing functionality as much as possible.
3. Flag when the dbt project is using functionality that's not yet supported in Fusion, and ask users so they can choose whether to wait for feature support or remove use of unsupported features.

Migrating to the new authoring layer and the dbt Fusion engine

if a user says "migrate my dbt project to the new authoring layer" or "make my dbt project compatible with the Fusion engine" do the following steps and the migration is only successfully completed once dbtf compile finishes with 0 errors. Create a changes_made.md file documenting and summarizing all of the code changes made in the user's dbt project, including what the error was, the fix applied, and a summary of why the fix was chosen.

Before you begin, please read and understand the resources section below. Only apply fixes that are described in the provided Resources. Do not attempt undocumented fixes—if a solution isn't in these resources, inform the user and stop.

1. Run dbtf debug in the terminal to check their data platform connections. Proceed to step 2 if there are no errors. If there are errors, please summarize the error succinctly so the user knows how to debug on their own.

2. Run dbtf parse --show-all-deprecations in the terminal to check for compatibility errors in their current project. Summarize the log output by specifying how many errors were found and group the errors in a way that's easily understandable.

3. Install dbt-autofix and run autofix to try to fix errors. Prefer uv/uvx to install (uv tool install dbt-autofix) and run the package (uvx dbt-autofix deprecations), but fall back to pip and other methods if needed. Summarize the results of the autofix run and include how many errors were resolved. Run dbtf parse again to check for remaining errors and summarize with how many errors were found and a brief summary of the types of errors.

4. For remaining errors, please ONLY use the resources below to attempt to resolve them. If you can't figure out a fix from the resources below, notify the user and break out of the flow. Attempt the fixes error by error, grouping similar errors based on the error code and message. You should also summarize which error you're working on in the chat to give users context.

   Special handling for common unsupported features:

   • Python model errors: Disable with {{ config(enabled=false) }} at the top of the file.

   Run dbtf parse throughout this step to check for progress towards completing the migration. Once dbtf parse finishes successfully with 0 errors, proceed to step 5.

5. Run dbtf compile in the terminal and check if it finishes with 0 errors. If it finishes with 0 errors, you have successfully completed the migration. If there are unresolved errors, try step 4 again. Except this time, use dbtf compile to check for progress towards completing the migration.

Don't Do These Things

1. At any point, if you run into a feature that's not yet supported on Fusion (not a deprecation!), please let the user know instead of trying to resolve it. Give the user the choice of removing the feature or manually addressing it themselves.

Handling Unsupported Features

When you encounter unsupported features in Fusion, follow this decision tree:

For Unsupported Model Types (Python models, etc.)

• Python models: Disable with {{ config(enabled=false) }} at the top of the file
• Materialized views/Dynamic tables: Disable with {{ config(enabled=false) }} at the top of the file

For Unsupported Config Keys

• Custom configs: Move to meta block in model files (see references/custom_configuration.md)
• Deprecated configs: Follow references/misspelled_config_keys.md guidance

For Dependency Issues

• If a model depends on an unsupported feature, disable the dependent model as well
• Update exposure dependencies to remove references to disabled models

Resources

Common problems that cannot be addressed with deterministic dbt-autofix

Use the files in the references/ directory as the context for resolving these common problems. Each file outlines one problem and the solution you should use:

• references/README.md - Overview of manual fixes
• references/custom_configuration.md - Custom config handling
• references/dynamic_sql.md - Dynamic SQL patterns
• references/iceberg_tables.md - Iceberg table support
• references/misspelled_config_keys.md - Deprecated/misspelled configs
• references/package_incompatibility.md - Package compatibility issues
• references/sources_without_tables.md - Sources without tables

Only follow what's specified in the file. If you need more context, use the dbt docs section below as a resource.

Unsupported features and blockers to Fusion compatibility. These pages outline the supported and unsupported features of the Fusion engine:

• https://docs.getdbt.com/docs/fusion/supported-features
• Unsupported features on Fusion: https://docs.getdbt.com/docs/fusion/supported-features#limitations
• https://docs.getdbt.com/docs/dbt-versions/core-upgrade/upgrading-to-fusion
• If a model type is unsupported on Fusion (e.g. python models), you can disable it with this jinja macro {{ config(enabled=false) }} at the top of the file to disable the model.

Config keys that Fusion should recognize: You can find the latest schema file using this template: https://public.cdn.getdbt.com/fs/schemas/fs-schema-{RESOURCE}-{VERSION}.json

• RESOURCE is either dbt-yaml-files or dbt-project
• VERSION is the fusion version (e.g. v2.0.0-beta.34, but https://public.cdn.getdbt.com/fs/latest.json gives you the latest version)
• Example file: https://public.cdn.getdbt.com/fs/schemas/fs-schema-dbt-yaml-files-v2.0.0-beta.34.json

dbt docs

https://docs.getdbt.com/reference/deprecations#list-of-deprecation-warnings https://github.com/dbt-labs/dbt-fusion/discussions/401 https://docs.getdbt.com/docs/fusion/supported-features https://docs.getdbt.com/docs/fusion/new-concepts