[GitHub] [phoenix] yanxinyi commented on a change in pull request #482: PHOENIX-4925 Use a Variant Segment tree to organize Guide Post Info

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yanxinyi commented on a change in pull request #482: PHOENIX-4925 Use a Variant Segment tree to organize Guide Post Info
URL: https://github.com/apache/phoenix/pull/482#discussion_r296970897
 
 

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 File path: phoenix-core/src/main/java/org/apache/phoenix/schema/stats/GuidePostChunk.java
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 @@ -0,0 +1,227 @@
+/*
+ * 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.phoenix.schema.stats;
+
+import com.google.common.collect.Lists;
+import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
+import org.apache.phoenix.query.KeyRange;
+import org.apache.phoenix.util.Closeables;
+import org.apache.phoenix.util.PrefixByteCodec;
+import org.apache.phoenix.util.PrefixByteDecoder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.ByteArrayInputStream;
+import java.io.DataInput;
+import java.io.DataInputStream;
+import java.io.EOFException;
+import java.util.List;
+
+/**
+ * A guide post chunk is comprised of a group of guide posts, and it has one of key ranges below:
+ *     (UNBOUND, gp_i0], (gp_i0, gp_i1], (gp_i1, gp_i2], ..., (gp_in, gp_n], (gp_n, UNBOUND)
+ * where gp_x is one of guide post collected on the server side. The last guide post chunk is a DUMMY chunk
+ * which contains one DUMMY guide post.
+ *
+ * Eventually the guide post chunk should be built and compressed on the server side when collecting stats.
+ * It is now the minimal data unit for compression/decompression and will be the minimal data unit stored
+ * into the SYSTEM_STATS table in the future.
+ */
+public final class GuidePostChunk {
+    public static final int INVALID_GUIDEPOST_CHUNK_INDEX = -1;
+    public static final Logger logger = LoggerFactory.getLogger(GuidePostChunk.class);
 
 Review comment:
   Let's use `LOGGER` instead of `logger` here.

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