Fix TypedConstraint equality check

Author: ericj-db

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Fixes
 
 - Fix inefficient query when getting column schema for MV/STs ([1074](https://github.com/databricks/dbt-databricks/issues/1074))
+- Fix bug causing false positives in diffing constraints between existing relation and model config for incremental runs ([1081](https://github.com/databricks/dbt-databricks/issues/1081))
 
 ## dbt-databricks 1.10.4 (June 24, 2025)
 

dbt/adapters/databricks/constraints.py

@@ -76,6 +76,14 @@ def __hash__(self) -> int:
         )
         return hash(fields)
 
+    def __eq__(self, other: Any) -> bool:
+        """Override equality to only compare fields used in hash calculation.
+
+        This ensures hash/equality contract is maintained and prevents issues
+        with set operations when warn_unenforced/warn_unsupported differ.
+        """
+        return self.__hash__() == other.__hash__()
+
 
 class CustomConstraint(TypedConstraint):
     str_type = "custom"

tests/functional/adapter/incremental/fixtures.py

@@ -1011,3 +1011,43 @@ def model(dbt, spark):
     data = [[1, 'hello', 'blue']]
     return spark.createDataFrame(data, schema=['id', 'msg', 'color'])
 """
+
+warn_unenforced_override_sql = """
+select "abc" as id
+"""
+
+warn_unenforced_override_model = """
+version: 2
+
+models:
+  - name: model_a
+    config:
+      materialized: incremental
+      on_schema_change: fail
+    columns:
+      - name: id
+        data_type: string
+        constraints:
+          - type: not_null
+    constraints:
+      - type: primary_key
+        columns:
+          - id
+        name: model_a_pk
+        warn_unenforced: false
+
+  - name: model_b
+    config:
+        materialized: table
+    columns:
+      - name: id
+        data_type: string
+    constraints:
+      - type: foreign_key
+        columns:
+          - id
+        name: model_b_fk
+        to: ref('model_a')
+        to_columns: [id]
+        warn_unenforced: false
+"""

tests/functional/adapter/incremental/test_incremental_constraints.py

@@ -216,6 +216,24 @@ def test_add_foreign_key_constraint(self, project):
         expected_pairs = {("fk_to_parent", "pk_parent"), ("fk_to_parent_2", "pk_parent_2")}
         assert constraint_pairs == expected_pairs
 
+    # Specifically for testing bugs like https://github.com/databricks/dbt-databricks/issues/1081
+    # where the config diff between the existing relation and model definition incorrectly detected
+    # constraints that were not changed. This is because the TypedConstraint read from existing
+    # Databricks relations will just have a default value for warn_unenforced which should
+    # be ignored during the diff
+    def test_warn_unenforced_false(self, project):
+        util.run_dbt(["run"])
+        referential_constraints = project.run_sql(referential_constraint_sql, fetch="all")
+        assert len(referential_constraints) == 0
+
+        util.write_file(fixtures.warn_unenforced_override_sql, "models", "model_a.sql")
+        util.write_file(fixtures.warn_unenforced_override_sql, "models", "model_b.sql")
+        util.write_file(fixtures.warn_unenforced_override_model, "models", "schema.yml")
+        util.run_dbt(["run"])
+        util.run_dbt(["run"])
+        referential_constraints = project.run_sql(referential_constraint_sql, fetch="all")
+        assert len(referential_constraints) == 1
+
 
 @pytest.mark.skip_profile("databricks_cluster")
 class TestIncrementalRemoveForeignKeyConstraint:

tests/unit/relation_configs/test_constraint.py

@@ -281,6 +281,7 @@ def test_get_diff__mixed_case(self):
                     type=ConstraintType.check,
                     name="check_name_length",
                     expression="LENGTH (name) >= 1",
+                    warn_unenforced=False,
                 ),
                 PrimaryKeyConstraint(
                     type=ConstraintType.primary_key,
@@ -296,6 +297,8 @@ def test_get_diff__mixed_case(self):
                     type=ConstraintType.check,
                     name="check_name_length",
                     expression="LENGTH (name) >= 1",
+                    # This should be ignored by the TypedConstraint equality check
+                    warn_unenforced=True,
                 ),
                 PrimaryKeyConstraint(
                     type=ConstraintType.primary_key,