[GitHub] StefanRRichter commented on a change in pull request #6875: [FLINK-9808] [state backends] Migrate state when necessary in state backends

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StefanRRichter commented on a change in pull request #6875: [FLINK-9808] [state backends] Migrate state when necessary in state backends
URL: https://github.com/apache/flink/pull/6875#discussion_r226683613
 
 

 ##########
 File path: flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/AbstractRocksDBState.java
 ##########
 @@ -154,6 +159,29 @@ public void setCurrentNamespace(N namespace) {
 		return backend.db.get(columnFamily, tmpKeySerializationView.getCopyOfBuffer());
 	}
 
+	public byte[] migrateSerializedValue(
+			byte[] serializedOldValue,
+			TypeSerializer<V> priorSerializer,
+			TypeSerializer<V> newSerializer) throws StateMigrationException {
+
+		try {
+			V value = priorSerializer.deserialize(new DataInputViewStreamWrapper(new ByteArrayInputStream(serializedOldValue)));
+
+			ByteArrayOutputStream baos = new ByteArrayOutputStream();
+			DataOutputViewStreamWrapper out = new DataOutputViewStreamWrapper(baos);
 
 Review comment:
   Better use `DataInputDeserializer` / `DataOutputSerializer` instead of wrapped byte-array streams. They are quiet a bit faster.

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