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Apache Hive adaptors for the DataSketches library.
/*
* 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.datasketches.hive.cpc;
import static org.apache.datasketches.Util.DEFAULT_UPDATE_SEED;
import org.apache.datasketches.cpc.CpcSketch;
import org.apache.datasketches.cpc.CpcUnion;
import org.apache.datasketches.hive.common.BytesWritableHelper;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.io.BytesWritable;
/**
* Hive union sketch UDF.
*/
@SuppressWarnings("deprecation")
public class UnionSketchUDF extends UDF {
/**
* Union two sketches given explicit lgK and seed
*
* @param firstSketch
* first sketch to be unioned.
* @param secondSketch
* second sketch to be unioned.
* @param lgK
* final output lgK
* This must be between 4 and 26.
* @param seed
* update seed
* @return resulting sketch of union.
*/
public BytesWritable evaluate(final BytesWritable firstSketch, final BytesWritable secondSketch,
final int lgK, final long seed) {
final CpcUnion union = new CpcUnion(lgK, seed);
if (firstSketch != null) {
union.update(CpcSketch.heapify(BytesWritableHelper.wrapAsMemory(firstSketch), seed));
}
if (secondSketch != null) {
union.update(CpcSketch.heapify(BytesWritableHelper.wrapAsMemory(secondSketch), seed));
}
return new BytesWritable(union.getResult().toByteArray());
}
/**
* Union two sketches given explicit lgK and using default seed
*
* @param firstSketch
* first sketch to be unioned.
* @param secondSketch
* second sketch to be unioned.
* @param lgK
* final output lgK
* This must be between 4 and 26.
* @return resulting sketch of union.
*/
public BytesWritable evaluate(final BytesWritable firstSketch, final BytesWritable secondSketch,
final int lgK) {
return evaluate(firstSketch, secondSketch, lgK, DEFAULT_UPDATE_SEED);
}
/**
* Union two sketches using default lgK an seed
*
* @param firstSketch
* first sketch to be unioned.
* @param secondSketch
* second sketch to be unioned.
* @return resulting sketch of union.
*/
public BytesWritable evaluate(final BytesWritable firstSketch, final BytesWritable secondSketch) {
return evaluate(firstSketch, secondSketch, SketchEvaluator.DEFAULT_LG_K, DEFAULT_UPDATE_SEED);
}
}
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