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/*
* Copyright 2017, Yahoo! Inc.
* Licensed under the terms of the Apache License 2.0. See LICENSE file at the project root for terms.
*/
package com.yahoo.sketches.hive.hll;
import java.util.Arrays;
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.StandardStructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils;
import com.yahoo.memory.Memory;
import com.yahoo.sketches.hll.HllSketch;
import com.yahoo.sketches.hll.TgtHllType;
/**
* Hive UDAF to compute union of HllSketch objects
*/
@Description(
name = "unionSketch",
value = "_FUNC_(sketch, lgK, type) - Compute the union of sketches of given size and seed",
extended = "Example:\n"
+ "> SELECT UnionSketch(sketch) 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'")
public class UnionSketchUDAF extends AbstractGenericUDAFResolver {
/**
* Perform argument count check and argument type checking, returns an
* appropriate evaluator to perform based on input type (which should always
* be BINARY sketch). Also check lgK and target HLL type parameters if they are passed in.
*
* @see org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver
* #getEvaluator(org.apache.hadoop.hive.ql.udf.generic.GenericUDAFParameterInfo)
*
* @param info The parameter info to validate
* @return The GenericUDAFEvaluator to use to compute the function.
*/
@Override
public GenericUDAFEvaluator getEvaluator(final GenericUDAFParameterInfo info) throws SemanticException {
final ObjectInspector[] inspectors = info.getParameterObjectInspectors();
if (inspectors.length < 1) {
throw new UDFArgumentException("Please specify at least 1 argument");
}
if (inspectors.length > 3) {
throw new UDFArgumentTypeException(inspectors.length - 1, "Please specify no more than 3 arguments");
}
ObjectInspectorValidator.validateGivenPrimitiveCategory(inspectors[0], 0, PrimitiveCategory.BINARY);
// 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 UnionSketchUDAFEvaluator();
}
/**
* Evaluator class, main logic of our UDAF.
*
*/
public static class UnionSketchUDAFEvaluator extends SketchEvaluator {
@SuppressWarnings("deprecation")
@Override
public AggregationBuffer getNewAggregationBuffer() throws HiveException {
return new UnionState();
}
/**
* Receives the passed in argument object inspectors and returns the desired
* return type's object inspector to inform hive of return type of UDAF.
*
* @param mode
* Mode (i.e. PARTIAL 1, COMPLETE...) for determining input and output
* object inspector type.
* @param parameters
* List of object inspectors for input arguments.
* @return The object inspector type indicates the UDAF return type (i.e.
* returned type of terminate(...)).
*/
@Override
public ObjectInspector init(final Mode mode, final ObjectInspector[] parameters) throws HiveException {
super.init(mode, parameters);
if ((mode == Mode.PARTIAL1) || (mode == Mode.COMPLETE)) {
inputInspector_ = (PrimitiveObjectInspector) parameters[0];
if (parameters.length > 1) {
lgKInspector_ = (PrimitiveObjectInspector) parameters[1];
}
if (parameters.length > 2) {
hllTypeInspector_ = (PrimitiveObjectInspector) parameters[2];
}
} else {
// mode = partial2 || final
intermediateInspector_ = (StandardStructObjectInspector) 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);
}
/**
* Add the incoming sketch into the internal state.
*
* @param buf
* aggregation buffer storing intermediate results.
* @param parameters
* sketches in the form of Object passed in to be merged.
*/
@Override
public void iterate(final @SuppressWarnings("deprecation") AggregationBuffer buf,
final Object[] parameters) throws HiveException {
if (parameters[0] == null) { return; }
final UnionState state = (UnionState) buf;
if (!state.isInitialized()) {
initializeState(state, parameters);
}
final byte[] serializedSketch = (byte[]) inputInspector_.getPrimitiveJavaObject(parameters[0]);
if (serializedSketch == null) { return; }
state.update(HllSketch.wrap(Memory.wrap(serializedSketch)));
}
private void initializeState(final UnionState 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);
}
}
}
