Feat: use 1 thread for dbt duckdb targets (#2222)

* Use 1 thread for dbt duckdb targets

* Add test

Author: treysp

sqlmesh/dbt/target.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import abc
+import logging
 import sys
 import typing as t
 from pathlib import Path
@@ -41,6 +42,8 @@
 else:
     from typing_extensions import Literal
 
+logger = logging.getLogger(__name__)
+
 IncrementalKind = t.Union[
     t.Type[IncrementalByUniqueKeyKind],
     t.Type[IncrementalByTimeRangeKind],
@@ -171,6 +174,8 @@ def validate_authentication(
                 if path is None or path == DUCKDB_IN_MEMORY
                 else Path(t.cast(str, path)).stem
             )
+        if "threads" in values and t.cast(int, values["threads"]) > 1:
+            logger.warning("DuckDB does not support concurrency - setting threads to 1.")
         return values
 
     def default_incremental_strategy(self, kind: IncrementalKind) -> str:
@@ -190,7 +195,7 @@ def to_sqlmesh(self) -> ConnectionConfig:
             kwargs["connector_config"] = self.settings
         return DuckDBConnectionConfig(
             database=self.path,
-            concurrent_tasks=self.threads,
+            concurrent_tasks=1,
             **kwargs,
         )
 

tests/dbt/test_config.py

@@ -1,6 +1,7 @@
 import base64
 import typing as t
 from pathlib import Path
+from shutil import copytree
 from unittest.mock import PropertyMock
 
 import pytest
@@ -12,6 +13,7 @@
 from sqlmesh.core.model import SqlModel
 from sqlmesh.dbt.common import Dependencies
 from sqlmesh.dbt.context import DbtContext
+from sqlmesh.dbt.loader import sqlmesh_config
 from sqlmesh.dbt.model import IncrementalByUniqueKeyKind, Materialization, ModelConfig
 from sqlmesh.dbt.project import Project
 from sqlmesh.dbt.source import SourceConfig
@@ -379,6 +381,29 @@ def _test_warehouse_config(
     return config
 
 
+def test_duckdb_threads(tmp_path):
+    dbt_project_dir = "tests/fixtures/dbt/sushi_test"
+    temp_dir = tmp_path / "sushi_test"
+
+    copytree(dbt_project_dir, temp_dir, symlinks=True)
+
+    with open(temp_dir / "profiles.yml", "w") as f:
+        f.write(
+            """
+            sushi:
+              outputs:
+                in_memory:
+                  type: duckdb
+                  schema: sushi
+                  threads: 4
+              target: in_memory
+            """
+        )
+
+    config = sqlmesh_config(temp_dir)
+    assert config.gateways["in_memory"].connection.concurrent_tasks == 1
+
+
 def test_snowflake_config():
     _test_warehouse_config(
         """