fix: table cache invalidation

target_snowflake/connector.py

@@ -116,6 +116,21 @@ def inspector(self) -> sqlalchemy.Inspector:
             self._inspector = sqlalchemy.inspect(self._engine)
         return self._inspector
 
+    def invalidate_table_cache(self, full_table_name: str) -> None:
+        """Discard cached reflection state for a table after DDL.
+
+        Dropping the `table_cache` entry alone is not enough. The Inspector
+        memoises reflection for its lifetime, and snowflake-sqlalchemy caches
+        columns per *schema*, so a table created after the first reflection of
+        that schema stays invisible and reflecting it raises NoSuchTableError.
+        The Inspector is dropped so the next reflection queries Snowflake.
+
+        Args:
+            full_table_name: the table whose cached state is now stale.
+        """
+        self.table_cache.pop(full_table_name, None)
+        self._inspector = None
+
     def get_table_columns(
         self,
         full_table_name: str | FullyQualifiedName,

target_snowflake/sinks.py

@@ -88,7 +88,7 @@ def setup(self) -> None:
                 self.conform_name(self.schema_name, object_type="schema"),
             )
 
-        self.connector.table_cache.pop(self.full_table_name, None)
+        self.connector.invalidate_table_cache(self.full_table_name)
 
         try:
             self.connector.prepare_table(
@@ -105,7 +105,7 @@ def setup(self) -> None:
             )
             raise
 
-        self.connector.table_cache.pop(self.full_table_name, None)
+        self.connector.invalidate_table_cache(self.full_table_name)
 
         if self.config.get("load_method", "upsert") == "overwrite":
             self.logger.info("load_method=overwrite: truncating %s", self.full_table_name)

tests/unit/test_connector.py

@@ -193,3 +193,37 @@ def test_format_identifier(connector: SnowflakeConnector, config: dict, identifi
     connector.config.update(config)
     formatted = connector.format_identifier(identifier)
     assert formatted == expected_formatted
+
+
+def test_invalidate_table_cache_drops_inspector(connector: SnowflakeConnector):
+    """Invalidating a table must drop the cached Inspector, not just table_cache.
+
+    snowflake-sqlalchemy memoises columns per schema on the Inspector, so
+    reusing it after a CREATE TABLE reflects the schema as it was before the
+    table existed and raises NoSuchTableError.
+    """
+    connector.table_cache["DB.SCHEMA.USERS"] = {"id": mock.Mock()}
+    connector.table_cache["DB.SCHEMA.POSTS"] = {"id": mock.Mock()}
+    connector._inspector = mock.Mock(spec=sa.Inspector)
+
+    connector.invalidate_table_cache("DB.SCHEMA.USERS")
+
+    assert "DB.SCHEMA.USERS" not in connector.table_cache
+    assert "DB.SCHEMA.POSTS" in connector.table_cache
+    assert connector._inspector is None
+
+
+def test_inspector_rebuilt_after_invalidation(connector: SnowflakeConnector):
+    """A fresh Inspector is built on next access, so reflection re-queries."""
+    connector._cached_engine = mock.Mock()
+
+    with mock.patch("sqlalchemy.inspect") as inspect_mock:
+        inspect_mock.side_effect = [mock.sentinel.stale, mock.sentinel.fresh]
+
+        assert connector.inspector is mock.sentinel.stale
+        assert connector.inspector is mock.sentinel.stale  # cached
+
+        connector.invalidate_table_cache("DB.SCHEMA.USERS")
+
+        assert connector.inspector is mock.sentinel.fresh
+        assert inspect_mock.call_count == 2

tests/unit/test_sinks.py

@@ -7,9 +7,11 @@
 from unittest import mock
 
 import pytest
+import sqlalchemy as sa
 from singer_sdk.helpers._batch import JSONLinesEncoding
 
 from target_snowflake.arrow_batch import ArrowEncoding
+from target_snowflake.connector import SnowflakeConnector
 from target_snowflake.sinks import SnowflakeSink
 
 
@@ -148,3 +150,42 @@ def fake_convert(manifest, output_dir, *, clean_up_source_files):  # noqa: ARG00
         SnowflakeSink._process_arrow_batch_files(fake_sink, ["file:///tmp/a.arrow"])  # noqa: SLF001
 
     assert not os.path.exists(captured_output_dir["path"])
+
+
+def test_setup_invalidates_cached_inspector():
+    """setup() must drop the connector's cached Inspector after creating the table.
+
+    snowflake-sqlalchemy memoises columns per schema on the Inspector, so a table
+    created here stays invisible to later reflection unless the Inspector is
+    dropped. That surfaced as NoSuchTableError in activate_version for every
+    stream after the first.
+    """
+    connector = SnowflakeConnector(
+        config={
+            "user": "test_user",
+            "password": "test_password",
+            "account": "test_account",
+            "database": "TEST_DATABASE",
+        },
+    )
+    connector._inspector = mock.Mock(spec=sa.Inspector)
+    connector.table_cache["DB.SCHEMA.TABLE"] = {"id": mock.Mock()}
+    connector.prepare_schema = mock.MagicMock()
+    connector.prepare_table = mock.MagicMock()
+
+    fake_sink = SimpleNamespace(
+        schema_name="SCHEMA",
+        full_table_name="DB.SCHEMA.TABLE",
+        schema={},
+        key_properties=[],
+        config={},
+        logger=mock.MagicMock(),
+        connector=connector,
+        conform_name=lambda name, object_type=None: name,  # noqa: ARG005
+        conform_schema=lambda schema: schema,
+    )
+
+    SnowflakeSink.setup(fake_sink)
+
+    assert connector._inspector is None
+    assert "DB.SCHEMA.TABLE" not in connector.table_cache