| /** |
| * 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.math.BigDecimal; |
| import java.sql.ResultSet; |
| import java.sql.SQLException; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| 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 BigDecimal values. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Evolving |
| public class BigDecimalSplitter implements DBSplitter { |
| private static final Log LOG = LogFactory.getLog(BigDecimalSplitter.class); |
| |
| public List<InputSplit> split(Configuration conf, ResultSet results, String colName) |
| throws SQLException { |
| |
| BigDecimal minVal = results.getBigDecimal(1); |
| BigDecimal maxVal = results.getBigDecimal(2); |
| |
| String lowClausePrefix = colName + " >= "; |
| String highClausePrefix = colName + " < "; |
| |
| BigDecimal numSplits = new BigDecimal(conf.getInt(MRJobConfig.NUM_MAPS, 1)); |
| |
| if (minVal == null && maxVal == 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; |
| } |
| |
| if (minVal == null || maxVal == null) { |
| // Don't know what is a reasonable min/max value for interpolation. Fail. |
| LOG.error("Cannot find a range for NUMERIC or DECIMAL fields with one end NULL."); |
| return null; |
| } |
| |
| // Get all the split points together. |
| List<BigDecimal> splitPoints = split(numSplits, minVal, maxVal); |
| List<InputSplit> splits = new ArrayList<InputSplit>(); |
| |
| // Turn the split points into a set of intervals. |
| BigDecimal start = splitPoints.get(0); |
| for (int i = 1; i < splitPoints.size(); i++) { |
| BigDecimal end = splitPoints.get(i); |
| |
| if (i == splitPoints.size() - 1) { |
| // This is the last one; use a closed interval. |
| splits.add(new DataDrivenDBInputFormat.DataDrivenDBInputSplit( |
| lowClausePrefix + start.toString(), |
| colName + " <= " + end.toString())); |
| } else { |
| // Normal open-interval case. |
| splits.add(new DataDrivenDBInputFormat.DataDrivenDBInputSplit( |
| lowClausePrefix + start.toString(), |
| highClausePrefix + end.toString())); |
| } |
| |
| start = end; |
| } |
| |
| return splits; |
| } |
| |
| private static final BigDecimal MIN_INCREMENT = new BigDecimal(10000 * Double.MIN_VALUE); |
| |
| /** |
| * Divide numerator by denominator. If impossible in exact mode, use rounding. |
| */ |
| protected BigDecimal tryDivide(BigDecimal numerator, BigDecimal denominator) { |
| try { |
| return numerator.divide(denominator); |
| } catch (ArithmeticException ae) { |
| return numerator.divide(denominator, BigDecimal.ROUND_HALF_UP); |
| } |
| } |
| |
| /** |
| * Returns a list of BigDecimals 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<BigDecimal> split(BigDecimal numSplits, BigDecimal minVal, BigDecimal maxVal) |
| throws SQLException { |
| |
| List<BigDecimal> splits = new ArrayList<BigDecimal>(); |
| |
| // Use numSplits as a hint. May need an extra task if the size doesn't |
| // divide cleanly. |
| |
| BigDecimal splitSize = tryDivide(maxVal.subtract(minVal), (numSplits)); |
| if (splitSize.compareTo(MIN_INCREMENT) < 0) { |
| splitSize = MIN_INCREMENT; |
| LOG.warn("Set BigDecimal splitSize to MIN_INCREMENT"); |
| } |
| |
| BigDecimal curVal = minVal; |
| |
| while (curVal.compareTo(maxVal) <= 0) { |
| splits.add(curVal); |
| curVal = curVal.add(splitSize); |
| } |
| |
| if (splits.get(splits.size() - 1).compareTo(maxVal) != 0 || splits.size() == 1) { |
| // We didn't end on the maxVal. Add that to the end of the list. |
| splits.add(maxVal); |
| } |
| |
| return splits; |
| } |
| } |