Spring Batch - simple Range Partitioner

This sample range partitioner could be used in Spring Batch application to partition data based on the Grid size and allocate them to individual executors.

[java]

package com.hashfold.spring.batch;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.springframework.batch.core.partition.support.Partitioner;
import org.springframework.batch.item.ExecutionContext;

public class RangePartitioner implements Partitioner {

private long start;
private long end;

public final void setStart(long start) {
this.start = start;
}

public final void setEnd(long end) {
this.end = end;
}

public RangePartitioner() {
}

@Override
public Map<String, ExecutionContext> partition(int gridSize) {

long rangeSize = end - start;
if (rangeSize <= 0)
return Collections.<String, ExecutionContext> emptyMap();

int numberOfIntervals = gridSize;
long sizeOfSmallSublists = rangeSize / numberOfIntervals;
long sizeOfLargeSublists = sizeOfSmallSublists + 1;
long numberOfLargeSublists = rangeSize % numberOfIntervals;
long numberOfSmallSublists = numberOfIntervals - numberOfLargeSublists;

Map<String, ExecutionContext> result = new HashMap<String, ExecutionContext>();

long numberOfElementsHandled = 0;

for (long i = 0; i < numberOfIntervals; i++) {

long size = i < numberOfSmallSublists ? sizeOfSmallSublists
: sizeOfLargeSublists;

long threadSeq = i + 1;
long startId = numberOfElementsHandled;
long endId = numberOfElementsHandled + size;

/*
* happens when range is less than the grid size. e.g. start=0, end
* = 2 and gridSize=3
*/
if ((endId - startId) <= 0)
continue;

ExecutionContext value = new ExecutionContext();

value.putLong("start", startId);

value.putLong("end", endId);

value.putString("name", "Thread-" + threadSeq);
result.put("partition" + threadSeq, value);

System.out.println("Starting : Thread-" + threadSeq + " : "
+ startId + " - " + endId);

numberOfElementsHandled += size;
}

return result;
}

// used only to test some cases. we should use junit and remove this method.
public static void main(String args[]) {
RangePartitioner rp = new RangePartitioner();
rp.setStart(1);
rp.setEnd(11);
rp.partition(3);

}

}

[/java]

Batch configuration change

[xml]

<!-- partitioner job -->
<job id="partitionJob" xmlns="http://www.springframework.org/schema/batch">

<!-- master step, 10 threads (grid-size) -->
<step id="masterStep">
<partition step="slave" partitioner="transactionPartitioner">
<handler grid-size="10" task-executor="taskExecutor" />
</partition>
</step>
</job>

<bean id="taskExecutor"
class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor">
<property name="corePoolSize" value="10" />
<property name="maxPoolSize" value="10" />
</bean>

<bean id="transactionPartitioner" class="com.hashfold.spring.batch.RangePartitioner">
<!-- we should process all records with range from [start, end). Note end is not included. it processes upto end-1-->
<property name="start" value="1" /> <!-- this number is included-->
<property name="end" value="11" /> <!-- this number is excluded-->
<!-- DB query should be executed with "WHERE ID >= :start and ID < :end" clause-->
</bean>

[/xml]

SQL Operators order by the performance

 

key operators used in the WHERE clause, ordered by their performance. Those operators at the top will produce results faster than those listed at the bottom.

=
>
>=
<
<=
LIKE
<>

 

via here