Package org.apache.tajo.engine.planner.physical

Source Code of org.apache.tajo.engine.planner.physical.HashPartitioner

/**
* 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.tajo.engine.planner.physical;

import org.apache.tajo.storage.Tuple;
import org.apache.tajo.storage.VTuple;

public class HashPartitioner extends Partitioner {
  private final Tuple keyTuple;
 
  public HashPartitioner(final int [] keys, final int numPartitions) {
    super(keys, numPartitions);
    this.keyTuple = new VTuple(partitionKeys.length);
  }
 
  @Override
  public int getPartition(Tuple tuple) {
    // build one key tuple
    for (int i = 0; i < partitionKeys.length; i++) {
      keyTuple.put(i, tuple.get(partitionKeys[i]));
    }
    return (keyTuple.hashCode() & Integer.MAX_VALUE) %
        (numPartitions == 32 ? numPartitions-1 : numPartitions);
  }
}
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