fix: clean up comments, add tests, and add changelog for identifier length validation (#1309)

Address review feedback:
- Remove verbose comment block from MAX_CHARACTERS_IN_IDENTIFIER constant
- Remove redundant inline comments from __post_init__ (implied by the code)
- Simplify the error message (no repetition of the limit value)
- Add TestIdentifierLengthValidation unit tests covering valid length,
  too-long raises DbtRuntimeError, no-type skips check, None identifier
- Add CHANGELOG entry under 1.11.7

https://claude.ai/code/session_017ZAXMwLSnqz4FqvTt5H7D1

Author: psaikaushik

CHANGELOG.md

@@ -10,6 +10,7 @@
 - Fix `workflow_job` Python model submission method failing with dictionary attribute error ([#1360](https://github.com/databricks/dbt-databricks/issues/1360))
 - Fix `TestWorkflowJob` functional test that was unreachable on all profiles due to incorrect skip list, wrong model fixture, and invalid `max_retries` parameter ([#1360](https://github.com/databricks/dbt-databricks/issues/1360))
 - Fix column order mismatch in microbatch and replace_where incremental strategies by using INSERT BY NAME syntax ([#1338](https://github.com/databricks/dbt-databricks/issues/1338))
+- Validate relation identifier length at creation time and raise a clear error when it exceeds Databricks' 255-character limit, preventing confusing runtime failures when `store_failures: true` generates long table names ([#1309](https://github.com/databricks/dbt-databricks/issues/1309))
 - Fix `dbt run --empty` failing with inline `ref()` / `source()` aliases ([dbt-labs/dbt-adapters#660](https://github.com/dbt-labs/dbt-adapters/issues/660))
 
 ### Under the Hood

dbt/adapters/databricks/relation.py

@@ -17,12 +17,6 @@
 from dbt.adapters.databricks.utils import remove_undefined
 
 KEY_TABLE_PROVIDER = "Provider"
-
-# Databricks (Unity Catalog / Hive Metastore) enforces a 255-character limit
-# on table and view names. This constant is used by relation_max_name_length()
-# to validate identifier lengths at relation creation time rather than at
-# SQL execution time, providing a clear error message instead of a cryptic
-# DatabricksExecutionError.
 MAX_CHARACTERS_IN_IDENTIFIER = 255
 
 
@@ -93,23 +87,14 @@ class DatabricksRelation(BaseRelation):
     databricks_table_type: Optional[DatabricksTableType] = None
     temporary: Optional[bool] = False
 
-    def __post_init__(self):
-        # Validate identifier length against Databricks' 255-character limit.
-        # Check self.type to exclude test relation identifiers that may not
-        # have a type set yet.
-        if (
-            self.identifier is not None
-            and self.type is not None
-            and len(self.identifier) > self.relation_max_name_length()
-        ):
-            raise DbtRuntimeError(
-                f"Relation name '{self.identifier}' "
-                f"is longer than {self.relation_max_name_length()} characters. "
-                f"Databricks has a maximum identifier length of "
-                f"{self.relation_max_name_length()} characters. "
-                f"If this is a store_failures table, consider using a shorter "
-                f"test name or setting a custom alias."
-            )
+    def __post_init__(self) -> None:
+        if self.identifier and self.type:
+            if len(self.identifier) > self.relation_max_name_length():
+                raise DbtRuntimeError(
+                    f"Relation name '{self.identifier}' is longer than "
+                    f"{self.relation_max_name_length()} characters. "
+                    "Use a shorter test name or configure a custom alias."
+                )
 
     def relation_max_name_length(self):
         return MAX_CHARACTERS_IN_IDENTIFIER

tests/unit/test_relation.py

@@ -1,5 +1,6 @@
 import pytest
 from dbt_common.contracts.constraints import ConstraintType
+from dbt_common.exceptions import DbtRuntimeError
 
 from dbt.adapters.databricks import relation
 from dbt.adapters.databricks.constraints import (
@@ -8,6 +9,7 @@
     PrimaryKeyConstraint,
 )
 from dbt.adapters.databricks.relation import (
+    MAX_CHARACTERS_IN_IDENTIFIER,
     DatabricksQuotePolicy,
     DatabricksRelation,
     DatabricksRelationType,
@@ -370,6 +372,30 @@ def test_render_constraints_for_create__with_constraints(
         assert relation.render_constraints_for_create() == "a > 1, PRIMARY KEY (a)"
 
 
+class TestIdentifierLengthValidation:
+    def test_relation_max_name_length(self):
+        assert DatabricksRelation.relation_max_name_length() == MAX_CHARACTERS_IN_IDENTIFIER
+
+    def test_valid_identifier_length(self):
+        identifier = "a" * MAX_CHARACTERS_IN_IDENTIFIER
+        rel = DatabricksRelation.create(identifier=identifier, type="table")
+        assert rel.identifier == identifier
+
+    def test_identifier_too_long_raises(self):
+        identifier = "a" * (MAX_CHARACTERS_IN_IDENTIFIER + 1)
+        with pytest.raises(DbtRuntimeError, match="longer than 255 characters"):
+            DatabricksRelation.create(identifier=identifier, type="table")
+
+    def test_long_identifier_without_type_is_allowed(self):
+        identifier = "a" * (MAX_CHARACTERS_IN_IDENTIFIER + 1)
+        rel = DatabricksRelation.create(identifier=identifier)
+        assert rel.identifier == identifier
+
+    def test_none_identifier_is_allowed(self):
+        rel = DatabricksRelation.create(identifier=None, type="table")
+        assert rel.identifier is None
+
+
 class TestDatabricksRenderLimited:
     def test_render_limited_with_empty_no_alias(self):
         relation = DatabricksRelation.create(