Merge pull request #298 from duckdb/jwills_add_retries_for_some_errors

Add support for retrying certain types of exceptions we see when running models with DuckDB

Author: jwills

dbt/adapters/duckdb/credentials.py

@@ -1,6 +1,7 @@
 import os
 import time
 from dataclasses import dataclass
+from dataclasses import field
 from functools import lru_cache
 from typing import Any
 from typing import Dict
@@ -61,6 +62,20 @@ class Remote(dbtClassMixin):
     password: Optional[str] = None
 
 
+@dataclass
+class Retries(dbtClassMixin):
+    # The number of times to attempt the initial duckdb.connect call
+    # (to wait for another process to free the lock on the DB file)
+    connect_attempts: int = 1
+
+    # The number of times to attempt to execute a DuckDB query that throws
+    # one of the retryable exceptions
+    query_attempts: Optional[int] = None
+
+    # The list of exceptions that we are willing to retry on
+    retryable_exceptions: List[str] = field(default_factory=lambda: ["IOException"])
+
+
 @dataclass
 class DuckDBCredentials(Credentials):
     database: str = "main"
@@ -126,6 +141,11 @@ class DuckDBCredentials(Credentials):
     # provide helper functions for dbt Python models.
     module_paths: Optional[List[str]] = None
 
+    # An optional strategy for allowing retries when certain types of
+    # exceptions occur on a model run (e.g., IOExceptions that were caused
+    # by networking issues)
+    retries: Optional[Retries] = None
+
     @classmethod
     def __pre_deserialize__(cls, data: Dict[Any, Any]) -> Dict[Any, Any]:
         data = super().__pre_deserialize__(data)

dbt/adapters/duckdb/environments/__init__.py

@@ -3,7 +3,9 @@
 import os
 import sys
 import tempfile
+import time
 from typing import Dict
+from typing import List
 from typing import Optional
 
 import duckdb
@@ -31,6 +33,44 @@ def _ensure_event_loop():
         asyncio.set_event_loop(loop)
 
 
+class RetryableCursor:
+    def __init__(self, cursor, retry_attempts: int, retryable_exceptions: List[str]):
+        self._cursor = cursor
+        self._retry_attempts = retry_attempts
+        self._retryable_exceptions = retryable_exceptions
+
+    def execute(self, sql: str, bindings=None):
+        attempt, success, exc = 0, False, None
+        while not success and attempt < self._retry_attempts:
+            try:
+                if bindings is None:
+                    self._cursor.execute(sql)
+                else:
+                    self._cursor.execute(sql, bindings)
+                success = True
+            except Exception as e:
+                exception_name = type(e).__name__
+                if exception_name in self._retryable_exceptions:
+                    time.sleep(2**attempt)
+                    exc = e
+                    attempt += 1
+                else:
+                    print(f"Did not retry exception named '{exception_name}'")
+                    raise e
+        if not success:
+            if exc:
+                raise exc
+            else:
+                raise RuntimeError(
+                    "execute call failed, but no exceptions raised- this should be impossible"
+                )
+        return self
+
+    # forward along all non-execute() methods/attribute look-ups
+    def __getattr__(self, name):
+        return getattr(self._cursor, name)
+
+
 class Environment(abc.ABC):
     """An Environment is an abstraction to describe *where* the code you execute in your dbt-duckdb project
     actually runs. This could be the local Python process that runs dbt (which is the default),
@@ -74,7 +114,32 @@ def initialize_db(
         cls, creds: DuckDBCredentials, plugins: Optional[Dict[str, BasePlugin]] = None
     ):
         config = creds.config_options or {}
-        conn = duckdb.connect(creds.path, read_only=False, config=config)
+
+        if creds.retries:
+            success, attempt, exc = False, 0, None
+            while not success and attempt < creds.retries.connect_attempts:
+                try:
+                    conn = duckdb.connect(creds.path, read_only=False, config=config)
+                    success = True
+                except Exception as e:
+                    exception_name = type(e).__name__
+                    if exception_name in creds.retries.retryable_exceptions:
+                        time.sleep(2**attempt)
+                        exc = e
+                        attempt += 1
+                    else:
+                        print(f"Did not retry exception named '{exception_name}'")
+                        raise e
+            if not success:
+                if exc:
+                    raise exc
+                else:
+                    raise RuntimeError(
+                        "connect call failed, but no exceptions raised- this should be impossible"
+                    )
+
+        else:
+            conn = duckdb.connect(creds.path, read_only=False, config=config)
 
         # install any extensions on the connection
         if creds.extensions is not None:
@@ -127,6 +192,11 @@ def initialize_cursor(
         for df_name, df in registered_df.items():
             cursor.register(df_name, df)
 
+        if creds.retries and creds.retries.query_attempts:
+            cursor = RetryableCursor(
+                cursor, creds.retries.query_attempts, creds.retries.retryable_exceptions
+            )
+
         return cursor
 
     @classmethod

tests/functional/plugins/test_plugins.py

@@ -91,6 +91,7 @@ def profiles_config_update(self, dbt_profile_target, sqlite_test_db):
                         "type": "duckdb",
                         "path": dbt_profile_target.get("path", ":memory:"),
                         "plugins": plugins,
+                        "retries": {"query_attempts": 2},
                     }
                 },
                 "target": "dev",

tests/unit/test_retries_connect.py

@@ -0,0 +1,36 @@
+import pytest
+from unittest.mock import patch
+
+from duckdb.duckdb import IOException
+
+from dbt.adapters.duckdb.credentials import DuckDBCredentials
+from dbt.adapters.duckdb.credentials import Retries
+from dbt.adapters.duckdb.environments import Environment
+
+class TestConnectRetries:
+
+    @pytest.fixture
+    def creds(self):
+        # Create a mock credentials object
+        return DuckDBCredentials(
+            path="foo.db",
+            retries=Retries(connect_attempts=2, retryable_exceptions=["IOException", "ArithmeticError"])
+        )
+
+    @pytest.mark.parametrize("exception", [None, IOException, ArithmeticError, ValueError])
+    def test_initialize_db(self, creds, exception):
+        # Mocking the duckdb.connect method
+        with patch('duckdb.connect') as mock_connect:
+            if exception:
+                mock_connect.side_effect = [exception, None]
+
+            if exception == ValueError:
+                with pytest.raises(ValueError) as excinfo:
+                    Environment.initialize_db(creds)
+            else:
+                # Call the initialize_db method
+                Environment.initialize_db(creds)
+                if exception in {IOException, ArithmeticError}:
+                    assert mock_connect.call_count == creds.retries.connect_attempts
+                else:
+                    mock_connect.assert_called_once_with(creds.path, read_only=False, config={})

tests/unit/test_retries_query.py

@@ -0,0 +1,57 @@
+import pytest
+from unittest.mock import MagicMock
+from unittest.mock import patch
+
+import duckdb
+
+from dbt.adapters.duckdb.credentials import Retries
+from dbt.adapters.duckdb.environments import RetryableCursor
+
+class TestRetryableCursor:
+
+    @pytest.fixture
+    def mock_cursor(self):
+        return MagicMock()
+
+    @pytest.fixture
+    def mock_retries(self):
+        return Retries(query_attempts=3)
+
+    @pytest.fixture
+    def retry_cursor(self, mock_cursor, mock_retries):
+        return RetryableCursor(
+            mock_cursor,
+            mock_retries.query_attempts,
+            mock_retries.retryable_exceptions)
+
+    def test_successful_execute(self, mock_cursor, retry_cursor):
+        """ Test that execute successfully runs the SQL query. """
+        sql_query = "SELECT * FROM table"
+        retry_cursor.execute(sql_query)
+        mock_cursor.execute.assert_called_once_with(sql_query)
+
+    def test_retry_on_failure(self, mock_cursor, retry_cursor):
+        """ Test that execute retries the SQL query on failure. """
+        mock_cursor.execute.side_effect = [duckdb.duckdb.IOException, None]
+        sql_query = "SELECT * FROM table"
+        retry_cursor.execute(sql_query)
+        assert mock_cursor.execute.call_count == 2
+
+    def test_no_retry_on_non_retryable_exception(self, mock_cursor, retry_cursor):
+        """ Test that a non-retryable exception is not retried. """
+        mock_cursor.execute.side_effect = ValueError
+        sql_query = "SELECT * FROM table"
+        with pytest.raises(ValueError):
+            retry_cursor.execute(sql_query)
+        mock_cursor.execute.assert_called_once_with(sql_query)
+
+    def test_exponential_backoff(self, mock_cursor, retry_cursor):
+        """ Test that exponential backoff is applied between retries. """
+        mock_cursor.execute.side_effect = [duckdb.duckdb.IOException, duckdb.duckdb.IOException, None]
+        sql_query = "SELECT * FROM table"
+
+        with patch("time.sleep") as mock_sleep:
+            retry_cursor.execute(sql_query)
+            assert mock_sleep.call_count == 2
+            mock_sleep.assert_any_call(1)
+            mock_sleep.assert_any_call(2)