Unwrap parenthesized single-column Redshift distkey

A parenthesized distkey such as `distkey = (col)` rendered as
`DISTKEY((col))`, which doesn't match Redshift's documented
`DISTKEY ( column_name )` syntax. Unwrap the parentheses the same way
the sortkey handling does, and test the bare, quoted, string and
parenthesized forms in model physical_properties.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: Simen Strand <simen.strand@netcheck.de>

Author: simen-strand

sqlmesh/core/engine_adapter/redshift.py

@@ -291,7 +291,9 @@ def _to_identifier_if_string(expression: exp.Expr) -> exp.Expr:
 
             distkey = table_properties.get("DISTKEY")
             if distkey:
-                properties.append(exp.DistKeyProperty(this=_to_identifier_if_string(distkey)))
+                properties.append(
+                    exp.DistKeyProperty(this=_to_identifier_if_string(distkey.unnest()))
+                )
 
             sortkey = table_properties.get("SORTKEY")
             if sortkey:

tests/core/engine_adapter/test_redshift.py

@@ -198,6 +198,44 @@ def test_create_table_physical_properties_from_model_definition(
     ]
 
 
+@pytest.mark.parametrize(
+    "distkey",
+    ['"id_file"', "id_file", "'id_file'", '("id_file")', "(id_file)"],
+)
+def test_create_table_physical_properties_distkey_from_model_definition(
+    make_mocked_engine_adapter: t.Callable, distkey: str
+):
+    adapter = make_mocked_engine_adapter(RedshiftEngineAdapter)
+    model: SqlModel = t.cast(
+        SqlModel,
+        load_sql_based_model(
+            d.parse(
+                f"""
+MODEL (
+    name test_schema.test_table,
+    kind full,
+    physical_properties (
+        diststyle = key,
+        distkey = {distkey}
+    )
+);
+SELECT id_file::INT;
+    """
+            )
+        ),
+    )
+
+    adapter.create_table(
+        model.name,
+        target_columns_to_types=model.columns_to_types_or_raise,
+        table_properties=model.physical_properties,
+    )
+
+    assert to_sql_calls(adapter) == [
+        'CREATE TABLE IF NOT EXISTS "test_schema"."test_table" ("id_file" INTEGER) DISTSTYLE KEY DISTKEY("id_file")',
+    ]
+
+
 def test_varchar_size_workaround(make_mocked_engine_adapter: t.Callable, mocker: MockerFixture):
     adapter = make_mocked_engine_adapter(RedshiftEngineAdapter)