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* 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.hll;
import java.util.Arrays;
import org.apache.datasketches.hll.TgtHllType;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFParameterInfo;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector.PrimitiveCategory;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils;
/**
* Hive UDAF to create an HllSketch from raw data.
*/
@Description(
name = "dataToSketch",
value = "_FUNC_(expr, lgK, type) - "
+ "Compute a sketch on data 'expr' with given parameters lgK and target type",
extended = "Example:\n"
+ "> SELECT dataToSketch(val, 12) FROM src;\n"
+ "The return value is a binary blob that can be operated on by other sketch related functions."
+ " The lgK parameter controls the sketch size and rlative error expected from the sketch."
+ " It is optional an must be from 4 to 21. The default is 12, which is expected to yield errors"
+ " of roughly +-3% in the estimation of uniques with 95% confidence."
+ " The target type parameter is optional and must be 'HLL_4', 'HLL_6' or 'HLL_8'."
+ " The default is 'HLL_4'")
@SuppressWarnings("javadoc")
public class DataToSketchUDAF extends AbstractGenericUDAFResolver {
/**
* Performs argument number and type validation. DataToSketch expects
* to receive between one and three arguments.
* <ul>
* <li>The first (required) is the value to add to the sketch and must be a primitive.</li>
*
* <li>The second (optional) is the lgK from 4 to 21 (default 12).
* This must be an integral value and must be constant.</li>
*
* <li>The third (optional) is the target HLL type and must be a string 'HLL_4',
* 'HLL_6' or 'HLL_8' (default 'HLL_4').</li>
* </ul>
*
* @see org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver
* #getEvaluator(org.apache.hadoop.hive.ql.udf.generic.GenericUDAFParameterInfo)
*
* @param info Parameter info to validate
* @return The GenericUDAFEvaluator that should be used to calculate the function.
*/
@Override
public GenericUDAFEvaluator getEvaluator(final GenericUDAFParameterInfo info) throws SemanticException {
final ObjectInspector[] inspectors = info.getParameterObjectInspectors();
// Validate the correct number of parameters
if (inspectors.length < 1) {
throw new UDFArgumentException("Please specify at least 1 argument");
}
if (inspectors.length > 3) {
throw new UDFArgumentException("Please specify no more than 3 arguments");
}
// Validate first parameter type
ObjectInspectorValidator.validateCategoryPrimitive(inspectors[0], 0);
// Validate second argument if present
if (inspectors.length > 1) {
ObjectInspectorValidator.validateIntegralParameter(inspectors[1], 1);
if (!ObjectInspectorUtils.isConstantObjectInspector(inspectors[1])) {
throw new UDFArgumentTypeException(1, "The second argument must be a constant");
}
}
// Validate third argument if present
if (inspectors.length > 2) {
ObjectInspectorValidator.validateGivenPrimitiveCategory(inspectors[2], 2, PrimitiveCategory.STRING);
if (!ObjectInspectorUtils.isConstantObjectInspector(inspectors[2])) {
throw new UDFArgumentTypeException(2, "The third argument must be a constant");
}
}
return new DataToSketchEvaluator();
}
public static class DataToSketchEvaluator extends SketchEvaluator {
private Mode mode_;
@SuppressWarnings("deprecation")
@Override
public AggregationBuffer getNewAggregationBuffer() throws HiveException {
// Different State is used for the iterate phase and the merge phase.
// A user reported that in some version of Hive this was apparently called before init,
// so the mode_ was null. A solution was implemented to have UnionState, which can work
// in both cases, but SketchState is more space-efficient.
// HLL sketch is about compactness, so let's use SketchState if possible.
if ((mode_ == Mode.PARTIAL1) || (mode_ == Mode.COMPLETE)) { // iterate() will be used
return new SketchState();
}
return new UnionState();
}
/*
* (non-Javadoc)
*
* @see
* org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator#init(org.apache
* .hadoop.hive.ql.udf.generic.GenericUDAFEvaluator.Mode,
* org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector[])
*/
@Override
public ObjectInspector init(final Mode mode, final ObjectInspector[] parameters) throws HiveException {
super.init(mode, parameters);
mode_ = mode;
if ((mode == Mode.PARTIAL1) || (mode == Mode.COMPLETE)) {
// input is original data
inputInspector_ = (PrimitiveObjectInspector) parameters[0];
if (parameters.length > 1) {
lgKInspector_ = (PrimitiveObjectInspector) parameters[1];
}
if (parameters.length > 2) {
hllTypeInspector_ = (PrimitiveObjectInspector) parameters[2];
}
} else {
// input for PARTIAL2 and FINAL is the output from PARTIAL1
intermediateInspector_ = (StructObjectInspector) parameters[0];
}
if ((mode == Mode.PARTIAL1) || (mode == Mode.PARTIAL2)) {
// intermediate results need to include the lgK and the target HLL type
return ObjectInspectorFactory.getStandardStructObjectInspector(
Arrays.asList(LG_K_FIELD, HLL_TYPE_FIELD, SKETCH_FIELD),
Arrays.asList(
PrimitiveObjectInspectorFactory.getPrimitiveWritableObjectInspector(PrimitiveCategory.INT),
PrimitiveObjectInspectorFactory.getPrimitiveWritableObjectInspector(PrimitiveCategory.STRING),
PrimitiveObjectInspectorFactory.getPrimitiveWritableObjectInspector(PrimitiveCategory.BINARY)
)
);
}
// final results include just the sketch
return PrimitiveObjectInspectorFactory.getPrimitiveWritableObjectInspector(PrimitiveCategory.BINARY);
}
/*
* (non-Javadoc)
*
* @see
* org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator#iterate(org
* .apache
* .hadoop.hive.ql.udf.generic.GenericUDAFEvaluator.AggregationBuffer,
* java.lang.Object[])
*/
@Override
public void iterate(final @SuppressWarnings("deprecation") AggregationBuffer agg,
final Object[] parameters) throws HiveException {
if (parameters[0] == null) { return; }
final State state = (State) agg;
if (!state.isInitialized()) {
initializeState(state, parameters);
}
state.update(parameters[0], inputInspector_);
}
private void initializeState(final State state, final Object[] parameters) {
int lgK = DEFAULT_LG_K;
if (lgKInspector_ != null) {
lgK = PrimitiveObjectInspectorUtils.getInt(parameters[1], lgKInspector_);
}
TgtHllType type = DEFAULT_HLL_TYPE;
if (hllTypeInspector_ != null) {
type = TgtHllType.valueOf(PrimitiveObjectInspectorUtils.getString(parameters[2], hllTypeInspector_));
}
state.init(lgK, type);
}
}
}
