/**
* 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.sqoop.mapreduce.db;
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.conf.Configuration;
import org.apache.hadoop.mapreduce.InputSplit;
import com.cloudera.sqoop.config.ConfigurationHelper;
import com.cloudera.sqoop.mapreduce.db.DBSplitter;
import com.cloudera.sqoop.mapreduce.db.DataDrivenDBInputFormat;
/**
* Implement DBSplitter over integer values.
*/
public class IntegerSplitter implements DBSplitter {
public static final Log LOG =
LogFactory.getLog(IntegerSplitter.class.getName());
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 = ConfigurationHelper.getConfNumMaps(conf);
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;
}
long splitLimit = org.apache.sqoop.config.ConfigurationHelper.getSplitLimit(conf);
// Get all the split points together.
List<Long> splitPoints = split(numSplits,splitLimit, minVal, maxVal);
if (LOG.isDebugEnabled()) {
LOG.debug(String.format("Splits: [%,28d to %,28d] into %d parts",
minVal, maxVal, numSplits));
for (int i = 0; i < splitPoints.size(); i++) {
LOG.debug(String.format("%,28d", splitPoints.get(i)));
}
}
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.
*
* @param numSplits Number of split chunks.
* @param splitLimit Limit the split size.
* @param minVal Minimum value of the set to split.
* @param maxVal Maximum value of the set to split.
* @return Split values inside the set.
* @throws SQLException In case of SQL exception.
*/
public List<Long> split(long numSplits,long splitLimit, long minVal, long maxVal)
throws SQLException {
List<Long> splits = new ArrayList<Long>();
// We take the min-max interval and divide by the numSplits and also
// calculate a remainder. Because of integer division rules, numsplits *
// splitSize + minVal will always be <= maxVal. We then use the remainder
// and add 1 if the current split index is less than the < the remainder.
// This is guaranteed to add up to remainder and not surpass the value.
long splitSize = (maxVal - minVal) / numSplits;
double splitSizeDouble = ((double)maxVal - (double)minVal) / (double)numSplits;
if (splitLimit > 0 && splitSizeDouble > splitLimit) {
// If split size is greater than limit then do the same thing with larger
// amount of splits.
LOG.debug("Adjusting split size " + splitSize
+ " because it's greater than limit " + splitLimit);
long newSplits = (maxVal - minVal) / splitLimit;
return split(newSplits != numSplits ? newSplits : newSplits + 1,
splitLimit, minVal, maxVal);
}
LOG.info("Split size: " + splitSize + "; Num splits: " + numSplits
+ " from: " + minVal + " to: " + maxVal);
long remainder = (maxVal - minVal) % numSplits;
long curVal = minVal;
// This will honor numSplits as long as split size > 0. If split size is
// 0, it will have remainder splits.
for (int i = 0; i <= numSplits; i++) {
splits.add(curVal);
if (curVal >= maxVal) {
break;
}
curVal += splitSize;
curVal += (i < remainder) ? 1 : 0;
}
if (splits.size() == 1) {
// make a valid singleton split
splits.add(maxVal);
} else if ((maxVal - minVal) <= numSplits) {
// Edge case when there is lesser split points (intervals) then
// requested number of splits. In such case we are creating last split
// with two values, for example interval [1, 5] broken down into 5
// splits will create following conditions:
// * 1 <= x < 2
// * 2 <= x < 3
// * 3 <= x < 4
// * 4 <= x <= 5
// Notice that the last split have twice more data than others. In
// those cases we add one maxVal at the end to create following splits
// instead:
// * 1 <= x < 2
// * 2 <= x < 3
// * 3 <= x < 4
// * 4 <= x < 5
// * 5 <= x <= 5
splits.add(maxVal);
}
return splits;
}
}