[GitHub] [beam] chamikaramj commented on a change in pull request #12023: [BEAM-10135] Add Python wrapper for Jdbc Write external transform

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chamikaramj commented on a change in pull request #12023:
URL: https://github.com/apache/beam/pull/12023#discussion_r448474601



##########
File path: sdks/python/apache_beam/io/external/jdbc.py
##########
@@ -0,0 +1,116 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""
+  PTransforms for supporting Jdbc in Python pipelines. These transforms do not
+  run a Jdbc client in Python. Instead, they expand to ExternalTransforms
+  which the Expansion Service resolves to the Java SDK's JdbcIO.
+
+  Note: To use these transforms, you need to start a Java Expansion Service.
+  Please refer to the portability documentation on how to do that. Flink Users
+  can use the built-in Expansion Service of the Flink Runner's Job Server. The
+  expansion service address has to be provided when instantiating the
+  transforms.
+
+  If you start Flink's Job Server, the expansion service will be started on
+  port 8097. This is also the configured default for this transform. For a

Review comment:
       We updated Kafka to build or download the IO expansion jar by default. Probably you can follow the same model here. I updated documentation for Kafka recently: https://github.com/apache/beam/pull/11928/files
   
   BTW one downside with a single IO expansion jar is that the size of the jar increases linearly with the number of cross-language wrappers that we have. This will increase the pipeline setup time for users since a larger jar has to be staged. What is the size increase of IO expansion jar due to this wrapper ? 
   
   cc: @robertwb 

##########
File path: sdks/python/apache_beam/io/external/jdbc.py
##########
@@ -0,0 +1,135 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""
+  PTransforms for supporting Jdbc in Python pipelines. These transforms do not
+  run a Jdbc client in Python. Instead, they expand to ExternalTransforms
+  which the Expansion Service resolves to the Java SDK's JdbcIO.
+
+  Note: To use these transforms, you need to start a Java Expansion Service.
+  Please refer to the portability documentation on how to do that. Flink Users
+  can use the built-in Expansion Service of the Flink Runner's Job Server. The
+  expansion service address has to be provided when instantiating the
+  transforms.
+
+  If you start Flink's Job Server, the expansion service will be started on
+  port 8097. This is also the configured default for this transform. For a
+  different address, please set the expansion_service parameter.
+
+  For more information see:
+  - https://beam.apache.org/documentation/runners/flink/
+  - https://beam.apache.org/roadmap/portability/
+"""
+
+# pytype: skip-file
+
+from __future__ import absolute_import
+
+import typing
+
+from past.builtins import unicode
+
+from apache_beam.transforms.external import BeamJarExpansionService
+from apache_beam.transforms.external import ExternalTransform
+from apache_beam.transforms.external import NamedTupleBasedPayloadBuilder
+
+__all__ = ['WriteToJdbc']

Review comment:
       Just curious. Were you able to successfully test this with portable Flink/Spark and Dataflow ?

##########
File path: sdks/python/apache_beam/io/external/jdbc.py
##########
@@ -0,0 +1,135 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""
+  PTransforms for supporting Jdbc in Python pipelines. These transforms do not
+  run a Jdbc client in Python. Instead, they expand to ExternalTransforms
+  which the Expansion Service resolves to the Java SDK's JdbcIO.
+
+  Note: To use these transforms, you need to start a Java Expansion Service.
+  Please refer to the portability documentation on how to do that. Flink Users
+  can use the built-in Expansion Service of the Flink Runner's Job Server. The
+  expansion service address has to be provided when instantiating the
+  transforms.
+
+  If you start Flink's Job Server, the expansion service will be started on
+  port 8097. This is also the configured default for this transform. For a
+  different address, please set the expansion_service parameter.
+
+  For more information see:
+  - https://beam.apache.org/documentation/runners/flink/
+  - https://beam.apache.org/roadmap/portability/
+"""
+
+# pytype: skip-file
+
+from __future__ import absolute_import
+
+import typing
+
+from past.builtins import unicode
+
+from apache_beam.transforms.external import BeamJarExpansionService
+from apache_beam.transforms.external import ExternalTransform
+from apache_beam.transforms.external import NamedTupleBasedPayloadBuilder
+
+__all__ = ['WriteToJdbc']
+
+
+def default_io_expansion_service():
+  return BeamJarExpansionService('sdks:java:io:expansion-service:shadowJar')
+
+
+WriteToJdbcSchema = typing.NamedTuple(
+    'WriteToJdbcSchema',
+    [
+        ('driver_class_name', unicode),
+        ('jdbc_url', unicode),
+        ('username', unicode),
+        ('password', unicode),
+        ('connection_properties', typing.Optional[unicode]),
+        ('connection_init_sqls', typing.Optional[typing.List[unicode]]),
+        ('statement', unicode),
+    ],
+)
+
+
+class WriteToJdbc(ExternalTransform):
+  """
+  An external PTransform which writes Rows to the specified database.
+
+  This transform receives Rows defined as NamedTuple type and registered in
+  the coders registry to use RowCoder, e.g.
+
+    import typing
+    from apache_beam import coders
+
+    ExampleRow = typing.NamedTuple(
+      "ExampleRow",
+      [
+        ("id", int),
+        ("name", unicode),
+        ("budget", float),
+      ],
+    )
+    coders.registry.register_coder(ExampleRow, coders.RowCoder)
+
+  Experimental; no backwards compatibility guarantees.  It requires special
+  preparation of the Java SDK.  See BEAM-7870.
+  """
+
+  URN = 'beam:external:java:jdbc:write:v1'
+
+  def __init__(
+      self,
+      driver_class_name,
+      jdbc_url,
+      username,
+      password,
+      statement,
+      **kwargs):
+    """
+    Initializes a write operation to Jdbc.
+
+    :param driver_class_name: name of the jdbc driver class

Review comment:
       Should these parameters be specified as strings ? Probably good if we can clarify that here.




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