feat(targets): Targets now accept a batch_size_rows setting to configure how many rows are loaded in each record batch

singer_sdk/helpers/capabilities.py

@@ -152,6 +152,13 @@
         default=True,
     ),
 ).to_dict()
+TARGET_BATCH_SIZE_ROWS_CONFIG = PropertiesList(
+    Property(
+        "batch_size_rows",
+        IntegerType,
+        description="Maximum number of rows in each batch.",
+    ),
+).to_dict()
 
 
 class TargetLoadMethods(str, Enum):

singer_sdk/sinks/core.py

@@ -182,6 +182,11 @@ def __init__(
         self._batch_records_read: int = 0
         self._batch_dupe_records_merged: int = 0
 
+        # Batch full markers
+        self._batch_size_rows: int | None = target.config.get(
+            "batch_size_rows",
+        )
+
         self._validator: BaseJSONSchemaValidator | None = self.get_validator()
 
     @cached_property
@@ -249,15 +254,6 @@ def _get_context(self, record: dict) -> dict:  # noqa: ARG002
 
     # Size properties
 
-    @property
-    def max_size(self) -> int:
-        """Get max batch size.
-
-        Returns:
-            Max number of records to batch before `is_full=True`
-        """
-        return self.MAX_SIZE_DEFAULT
-
     @property
     def current_size(self) -> int:
         """Get current batch size.
@@ -269,13 +265,40 @@ def current_size(self) -> int:
 
     @property
     def is_full(self) -> bool:
-        """Check against size limit.
+        """Check against the batch size limit.
 
         Returns:
             True if the sink needs to be drained.
         """
         return self.current_size >= self.max_size
 
+    @property
+    def batch_size_rows(self) -> int | None:
+        """The maximum number of rows a batch can accumulate before being processed.
+
+        Returns:
+            The max number of rows or None if not set.
+        """
+        return self._batch_size_rows
+
+    @property
+    def max_size(self) -> int:
+        """Get max batch size.
+
+        Returns:
+            Max number of records to batch before `is_full=True`
+
+        .. versionchanged:: 0.36.0
+           This property now takes into account the
+           :attr:`~singer_sdk.Sink.batch_size_rows` attribute and the corresponding
+           ``batch_size_rows`` target setting.
+        """
+        return (
+            self.batch_size_rows
+            if self.batch_size_rows is not None
+            else self.MAX_SIZE_DEFAULT
+        )
+
     # Tally methods
 
     @t.final

singer_sdk/target_base.py

@@ -18,6 +18,7 @@
 from singer_sdk.helpers.capabilities import (
     ADD_RECORD_METADATA_CONFIG,
     BATCH_CONFIG,
+    TARGET_BATCH_SIZE_ROWS_CONFIG,
     TARGET_HARD_DELETE_CONFIG,
     TARGET_LOAD_METHOD_CONFIG,
     TARGET_SCHEMA_CONFIG,
@@ -363,8 +364,9 @@ def _process_record_message(self, message_dict: dict) -> None:
 
             if sink.is_full:
                 self.logger.info(
-                    "Target sink for '%s' is full. Draining...",
+                    "Target sink for '%s' is full. Current size is '%s'. Draining...",
                     sink.stream_name,
+                    sink.current_size,
                 )
                 self.drain_one(sink)
 
@@ -610,6 +612,7 @@ def _merge_missing(source_jsonschema: dict, target_jsonschema: dict) -> None:
 
         _merge_missing(ADD_RECORD_METADATA_CONFIG, config_jsonschema)
         _merge_missing(TARGET_LOAD_METHOD_CONFIG, config_jsonschema)
+        _merge_missing(TARGET_BATCH_SIZE_ROWS_CONFIG, config_jsonschema)
 
         capabilities = cls.capabilities
 

tests/core/targets/test_target_sql.py

@@ -46,5 +46,9 @@ class MyTarget(SQLTargetMock, capabilities=capabilities):
         pass
 
     about = MyTarget._get_about_info()
-    default_settings = {"add_record_metadata", "load_method"}
+    default_settings = {
+        "add_record_metadata",
+        "load_method",
+        "batch_size_rows",
+    }
     assert set(about.settings["properties"]) == expected_settings | default_settings

tests/core/test_target_base.py

@@ -77,6 +77,7 @@ def test_target_about_info():
     assert "flattening_max_depth" in about.settings["properties"]
     assert "batch_config" in about.settings["properties"]
     assert "add_record_metadata" in about.settings["properties"]
+    assert "batch_size_rows" in about.settings["properties"]
 
 
 def test_sql_get_sink():
@@ -142,3 +143,40 @@ def test_add_sqlsink_and_get_sink():
         target.get_sink(
             "bar",
         )
+
+
+def test_batch_size_rows_and_max_size():
+    input_schema_1 = {
+        "properties": {
+            "id": {
+                "type": ["string", "null"],
+            },
+            "col_ts": {
+                "format": "date-time",
+                "type": ["string", "null"],
+            },
+        },
+    }
+    key_properties = []
+    target_default = TargetMock()
+    sink_default = BatchSinkMock(
+        target=target_default,
+        stream_name="foo",
+        schema=input_schema_1,
+        key_properties=key_properties,
+    )
+    target_set = TargetMock(config={"batch_size_rows": 100000})
+    sink_set = BatchSinkMock(
+        target=target_set,
+        stream_name="bar",
+        schema=input_schema_1,
+        key_properties=key_properties,
+    )
+    assert sink_default.stream_name == "foo"
+    assert sink_default._batch_size_rows is None
+    assert sink_default.batch_size_rows is None
+    assert sink_default.max_size == 10000
+    assert sink_set.stream_name == "bar"
+    assert sink_set._batch_size_rows == 100000
+    assert sink_set.batch_size_rows == 100000
+    assert sink_set.max_size == 100000