[GitHub] [flink] sjwiesman commented on a change in pull request #13179: [FLINK-18978][state-backends] Support full table scan of key and namespace from statebackend

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sjwiesman commented on a change in pull request #13179:
URL: https://github.com/apache/flink/pull/13179#discussion_r480295815



##########
File path: flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/iterator/RocksStateKeysAndNamespaceIterator.java
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@@ -0,0 +1,120 @@
+/*
+ * 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.flink.contrib.streaming.state.iterator;
+
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.contrib.streaming.state.RocksDBKeySerializationUtils;
+import org.apache.flink.contrib.streaming.state.RocksIteratorWrapper;
+import org.apache.flink.core.memory.DataInputDeserializer;
+import org.apache.flink.util.FlinkRuntimeException;
+
+import javax.annotation.Nonnull;
+
+import java.io.IOException;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+/**
+ * Adapter class to bridge between {@link RocksIteratorWrapper} and {@link Iterator} to iterate over the keys
+ * and namespaces. This class is not thread safe.
+ *
+ * @param <K> the type of the iterated keys in RocksDB.
+ * @param <N> the type of the iterated namespaces in RocksDB.
+ */
+public class RocksStateKeysAndNamespaceIterator<K, N> implements Iterator<Tuple2<K, N>>, AutoCloseable {

Review comment:
       -1 they are semantically similar but their `hasNext` methods are very different. In particular, the way they use the namespace bytes is quite different and I don't think a base class makes sense here. They both already share code via the `RocksDBSeySerializeionUtils` class. 




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