Github user StefanRRichter commented on a diff in the pull request:
https://github.com/apache/flink/pull/5582#discussion_r192076636
--- Diff:
flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBIncrementalCheckpointUtils.java
---
@@ -0,0 +1,80 @@
+/*
+ * 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;
+
+import org.apache.flink.runtime.state.KeyGroupRange;
+
+import org.rocksdb.ColumnFamilyHandle;
+import org.rocksdb.RocksDB;
+import org.rocksdb.RocksDBException;
+
+import java.util.List;
+
+/**
+ * Utils for RocksDB Incremental Checkpoint.
+ */
+public class RocksDBIncrementalCheckpointUtils {
+
+ public static void clipDBWithKeyGroupRange(
--- End diff --
I wonder if clipping the database to avoid prefix check is an optimization
or not? If we don't clip, the must seek the iterator and apply a single if to
every key. This if is very predictable for the CPU because it always passed
except for when we terminate the loop. This sounds rather cheap. What are your
thoughts about why deleting ranges is the better approach?
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