dbt Adapter Behavior¶

Truthound keeps one public macro surface and routes warehouse-specific SQL through adapter.dispatch. This page explains what that means in practice.

Why Adapter Dispatch Matters¶

Even simple validation rules are not fully portable across warehouses. Different adapters disagree on:

regex operators
length functions
safe cast syntax
current timestamp helpers
percentage rounding behavior
sampling and limit syntax

Truthound hides those differences behind shared macro names in truthound_utils.sql and related files.

What Stays Stable¶

The following stay stable across adapters:

test names
rule dictionaries
top-level run-operation macro names
the general result model exposed back to dbt

What Changes By Adapter¶

The compiled SQL may change for:

regex_match
regex_not_match
safe_cast
round_percentage
current_timestamp
window and sample helpers

That is expected. A compile diff between PostgreSQL and Snowflake does not mean the package surface changed.

Supported Warehouses¶

Truthound is designed for adapter-dispatched behavior across common dbt warehouses. The first-party suite in this repository currently proves the package through compile and PostgreSQL execution, while keeping the macro design ready for the broader dbt adapter family.

Operational Implications¶

compile success proves macro discovery and basic SQL generation
execute success proves that the adapter path works on a real warehouse
an adapter-specific runtime failure usually belongs in the utility macro layer, not in every individual test definition

Recent Compatibility Lessons¶

The package intentionally keeps adapter-specific logic centralized. For example:

package-qualified test discovery avoids ambiguous macro resolution
URL and numeric handling regressions are fixed in macro helpers rather than in each test case
percentage rounding must respect warehouse function signatures

Troubleshooting Checklist¶

If one warehouse fails but another compiles:

confirm the failing SQL path is adapter-specific
inspect the compiled macro output under target/compiled
check utility macros before touching dozens of test definitions