org.apache.hadoop.hive.ql.udf.generic.GenericUDFGrouping.java Source code

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Here is the source code for org.apache.hadoop.hive.ql.udf.generic.GenericUDFGrouping.java

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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.hadoop.hive.ql.udf.generic;

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.UDFType;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector.Category;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector.PrimitiveCategory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.IntObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.WritableConstantIntObjectInspector;
import org.apache.hadoop.io.IntWritable;

import com.google.common.math.IntMath;

/**
 * UDF grouping
 */
@Description(name = "grouping", value = "_FUNC_(a, p1, ..., pn) - Indicates whether a specified column expression in "
        + "is aggregated or not. Returns 1 for aggregated or 0 for not aggregated. ", extended = "a is the grouping id, p1...pn are the indices we want to extract")
@UDFType(deterministic = true)
public class GenericUDFGrouping extends GenericUDF {

    private transient IntObjectInspector groupingIdOI;
    private int[] indices;
    private IntWritable intWritable = new IntWritable();

    @Override
    public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {
        if (arguments.length < 2) {
            throw new UDFArgumentLengthException(
                    "grouping() requires at least 2 argument, got " + arguments.length);
        }

        if (arguments[0].getCategory() != Category.PRIMITIVE) {
            throw new UDFArgumentTypeException(0, "The first argument to grouping() must be primitive");
        }
        PrimitiveObjectInspector arg1OI = (PrimitiveObjectInspector) arguments[0];
        if (arg1OI.getPrimitiveCategory() != PrimitiveCategory.INT) {
            throw new UDFArgumentTypeException(0, "The first argument to grouping() must be an integer");
        }
        groupingIdOI = (IntObjectInspector) arguments[0];

        indices = new int[arguments.length - 1];
        for (int i = 1; i < arguments.length; i++) {
            PrimitiveObjectInspector arg2OI = (PrimitiveObjectInspector) arguments[i];
            if (!(arg2OI instanceof WritableConstantIntObjectInspector)) {
                throw new UDFArgumentTypeException(i, "Must be a constant");
            }
            indices[i - 1] = ((WritableConstantIntObjectInspector) arg2OI).getWritableConstantValue().get();
        }

        return PrimitiveObjectInspectorFactory.writableIntObjectInspector;
    }

    @Override
    public Object evaluate(DeferredObject[] arguments) throws HiveException {
        // groupingId = PrimitiveObjectInspectorUtils.getInt(arguments[0].get(), groupingIdOI);
        // Check that the bit at the given index is '1' or '0'
        int result = 0;
        // grouping(c1, c2, c3)
        // is equivalent to
        // 4 * grouping(c1) + 2 * grouping(c2) + grouping(c3)
        for (int a = 1; a < arguments.length; a++) {
            result += IntMath.pow(2, indices.length - a)
                    * ((PrimitiveObjectInspectorUtils.getInt(arguments[0].get(), groupingIdOI) >> indices[a - 1])
                            & 1);
        }
        intWritable.set(result);
        return intWritable;
    }

    @Override
    public String getDisplayString(String[] children) {
        assert (children.length > 1);
        return getStandardDisplayString("grouping", children);
    }

}