[GitHub] [beam] pabloem commented on a change in pull request #16011: [BEAM-12164] Add models for Spanner change streams

[GitBox <gi...@apache.org>]

pabloem commented on a change in pull request #16011:
URL: https://github.com/apache/beam/pull/16011#discussion_r752438052



##########
File path: sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/changestreams/model/ChangeStreamRecordMetadata.java
##########
@@ -0,0 +1,409 @@
+/*
+ * 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.
+ */
+package org.apache.beam.sdk.io.gcp.spanner.changestreams.model;
+
+import com.google.cloud.Timestamp;
+import java.io.Serializable;
+import java.util.Objects;
+import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.annotations.VisibleForTesting;
+
+/** Holds internal execution metrics / metadata for the processed {@link ChangeStreamRecord}. */
+public class ChangeStreamRecordMetadata implements Serializable {

Review comment:
       by implementing `Serializable` I suppose you're wanting to enable Beam to serialize your records using Java serialization. This makes sense, but you may want to consider removing the serializable, and instead annotating them with `@DefaultSchema(JavaBeanSchema.class)`. 
   
   Reasons why you may want to do that:
   - Beam serialization is faster and more compact than Java serialization
   - By adding a schema to it, you can apply 'smart' transformations to your data (e.g. `.apply(Select.columns("recordTimestamp", "partitionToken"));`
   
   See https://beam.apache.org/releases/javadoc/current/org/apache/beam/sdk/schemas/annotations/DefaultSchema.html and 
   see https://beam.apache.org/releases/javadoc/current/org/apache/beam/sdk/schemas/JavaBeanSchema.html

##########
File path: sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/changestreams/model/ChangeStreamRecordMetadata.java
##########
@@ -0,0 +1,409 @@
+/*
+ * 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.
+ */
+package org.apache.beam.sdk.io.gcp.spanner.changestreams.model;
+
+import com.google.cloud.Timestamp;
+import java.io.Serializable;
+import java.util.Objects;
+import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.annotations.VisibleForTesting;
+
+/** Holds internal execution metrics / metadata for the processed {@link ChangeStreamRecord}. */
+public class ChangeStreamRecordMetadata implements Serializable {

Review comment:
       The only thing to keep in mind (and maybe the reason why you're using Java serialization) is that you can only have one schema per PCollection - so if you have records of multiple kinds in the same PCollection, this approach may not be good.




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