| /** |
| * 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.hadoop.mapreduce.lib.db; |
| |
| import java.sql.ResultSet; |
| import java.sql.SQLException; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.mapreduce.InputSplit; |
| import org.apache.hadoop.mapreduce.MRJobConfig; |
| |
| /** |
| * Implement DBSplitter over integer values. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Evolving |
| public class IntegerSplitter implements DBSplitter { |
| public List<InputSplit> split(Configuration conf, ResultSet results, String colName) |
| throws SQLException { |
| |
| long minVal = results.getLong(1); |
| long maxVal = results.getLong(2); |
| |
| String lowClausePrefix = colName + " >= "; |
| String highClausePrefix = colName + " < "; |
| |
| int numSplits = conf.getInt(MRJobConfig.NUM_MAPS, 1); |
| if (numSplits < 1) { |
| numSplits = 1; |
| } |
| |
| if (results.getString(1) == null && results.getString(2) == null) { |
| // Range is null to null. Return a null split accordingly. |
| List<InputSplit> splits = new ArrayList<InputSplit>(); |
| splits.add(new DataDrivenDBInputFormat.DataDrivenDBInputSplit( |
| colName + " IS NULL", colName + " IS NULL")); |
| return splits; |
| } |
| |
| // Get all the split points together. |
| List<Long> splitPoints = split(numSplits, minVal, maxVal); |
| List<InputSplit> splits = new ArrayList<InputSplit>(); |
| |
| // Turn the split points into a set of intervals. |
| long start = splitPoints.get(0); |
| for (int i = 1; i < splitPoints.size(); i++) { |
| long end = splitPoints.get(i); |
| |
| if (i == splitPoints.size() - 1) { |
| // This is the last one; use a closed interval. |
| splits.add(new DataDrivenDBInputFormat.DataDrivenDBInputSplit( |
| lowClausePrefix + Long.toString(start), |
| colName + " <= " + Long.toString(end))); |
| } else { |
| // Normal open-interval case. |
| splits.add(new DataDrivenDBInputFormat.DataDrivenDBInputSplit( |
| lowClausePrefix + Long.toString(start), |
| highClausePrefix + Long.toString(end))); |
| } |
| |
| start = end; |
| } |
| |
| if (results.getString(1) == null || results.getString(2) == null) { |
| // At least one extrema is null; add a null split. |
| splits.add(new DataDrivenDBInputFormat.DataDrivenDBInputSplit( |
| colName + " IS NULL", colName + " IS NULL")); |
| } |
| |
| return splits; |
| } |
| |
| /** |
| * Returns a list of longs one element longer than the list of input splits. |
| * This represents the boundaries between input splits. |
| * All splits are open on the top end, except the last one. |
| * |
| * So the list [0, 5, 8, 12, 18] would represent splits capturing the intervals: |
| * |
| * [0, 5) |
| * [5, 8) |
| * [8, 12) |
| * [12, 18] note the closed interval for the last split. |
| */ |
| List<Long> split(long numSplits, long minVal, long maxVal) |
| throws SQLException { |
| |
| List<Long> splits = new ArrayList<Long>(); |
| |
| // Use numSplits as a hint. May need an extra task if the size doesn't |
| // divide cleanly. |
| |
| long splitSize = (maxVal - minVal) / numSplits; |
| if (splitSize < 1) { |
| splitSize = 1; |
| } |
| |
| long curVal = minVal; |
| |
| while (curVal <= maxVal) { |
| splits.add(curVal); |
| curVal += splitSize; |
| } |
| |
| if (splits.get(splits.size() - 1) != maxVal || splits.size() == 1) { |
| // We didn't end on the maxVal. Add that to the end of the list. |
| splits.add(maxVal); |
| } |
| |
| return splits; |
| } |
| } |