hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/DelimitedKeyPrefixRegionSplitPolicy.java

   1 /**
   2  * Licensed to the Apache Software Foundation (ASF) under one
   3  * or more contributor license agreements.  See the NOTICE file
   4  * distributed with this work for additional information
   5  * regarding copyright ownership.  The ASF licenses this file
   6  * to you under the Apache License, Version 2.0 (the
   7  * "License"); you may not use this file except in compliance
   8  * with the License.  You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  */
  18
  19 package org.apache.hadoop.hbase.regionserver;
  20
  21 import java.util.Arrays;
  22
  23 import org.apache.yetus.audience.InterfaceAudience;
  24 import org.slf4j.Logger;
  25 import org.slf4j.LoggerFactory;
  26 import org.apache.hadoop.hbase.util.Bytes;
  27
  28 /**
  29  * A custom RegionSplitPolicy implementing a SplitPolicy that groups
  30  * rows by a prefix of the row-key with a delimiter. Only the first delimiter
  31  * for the row key will define the prefix of the row key that is used for grouping.
  32  *
  33  * This ensures that a region is not split "inside" a prefix of a row key.
  34  * I.e. rows can be co-located in a region by their prefix.
  35  *
  36  * As an example, if you have row keys delimited with <code>_</code>, like
  37  * <code>userid_eventtype_eventid</code>, and use prefix delimiter _, this split policy
  38  * ensures that all rows starting with the same userid, belongs to the same region.
  39  * @see KeyPrefixRegionSplitPolicy
  40  *
  41  * @deprecated since 3.0.0 and will be removed in 4.0.0. Use {@link RegionSplitRestriction},
  42  *   instead.
  43  */
  44 @Deprecated
  45 @InterfaceAudience.Private
  46 public class DelimitedKeyPrefixRegionSplitPolicy extends IncreasingToUpperBoundRegionSplitPolicy {
  47
  48   private static final Logger LOG = LoggerFactory
  49       .getLogger(DelimitedKeyPrefixRegionSplitPolicy.class);
  50   public static final String DELIMITER_KEY = "DelimitedKeyPrefixRegionSplitPolicy.delimiter";
  51
  52   private byte[] delimiter = null;
  53
  54   @Override
  55   public String toString() {
  56     return "DelimitedKeyPrefixRegionSplitPolicy{" + "delimiter=" + Bytes.toStringBinary(delimiter) +
  57       ", " + super.toString() + '}';
  58   }
  59
  60   @Override
  61   protected void configureForRegion(HRegion region) {
  62     super.configureForRegion(region);
  63     // read the prefix length from the table descriptor
  64     String delimiterString = region.getTableDescriptor().getValue(DELIMITER_KEY);
  65     if (delimiterString == null || delimiterString.length() == 0) {
  66       LOG.error(DELIMITER_KEY + " not specified for table " +
  67         region.getTableDescriptor().getTableName() + ". Using default RegionSplitPolicy");
  68       return;
  69     }
  70     delimiter = Bytes.toBytes(delimiterString);
  71   }
  72
  73   @Override
  74   protected byte[] getSplitPoint() {
  75     byte[] splitPoint = super.getSplitPoint();
  76     if (splitPoint != null && delimiter != null) {
  77
  78       //find the first occurrence of delimiter in split point
  79       int index =
  80         org.apache.hbase.thirdparty.com.google.common.primitives.Bytes.indexOf(splitPoint, delimiter);
  81       if (index < 0) {
  82         LOG.warn("Delimiter " + Bytes.toString(delimiter) + "  not found for split key "
  83             + Bytes.toString(splitPoint));
  84         return splitPoint;
  85       }
  86
  87       // group split keys by a prefix
  88       return Arrays.copyOf(splitPoint, Math.min(index, splitPoint.length));
  89     } else {
  90       return splitPoint;
  91     }
  92   }
  93 }