/**
* 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 java.util.ArrayList;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFUtils.ReturnObjectInspectorResolver;
import org.apache.hadoop.hive.serde2.objectinspector.ConstantObjectInspector;
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.StructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.WritableConstantIntObjectInspector;
import org.apache.hadoop.io.IntWritable;
/**
* Takes a row of size k of data and splits it into n rows of data. For
* example, if n is 3 then the rest of the arguments are split in order into 3
* rows, each of which has k/3 columns in it (the first emitted row has the
* first k/3, the second has the second, etc). If n does not divide k then the
* remaining columns are padded with NULLs.
*/
@Description(
name = "stack",
value = "_FUNC_(n, cols...) - turns k columns into n rows of size k/n each"
)
public class GenericUDTFStack extends GenericUDTF {
@Override
public void close() throws HiveException {
}
ArrayList<ObjectInspector> argOIs = new ArrayList<ObjectInspector>();
Object[] forwardObj = null;
ArrayList<ReturnObjectInspectorResolver> returnOIResolvers =
new ArrayList<ReturnObjectInspectorResolver>();
IntWritable numRows = null;
Integer numCols = null;
@Override
public StructObjectInspector initialize(ObjectInspector[] args)
throws UDFArgumentException {
if (args.length < 2) {
throw new UDFArgumentException("STACK() expects at least two arguments.");
}
if (!(args[0] instanceof WritableConstantIntObjectInspector)) {
throw new UDFArgumentException(
"The first argument to STACK() must be a constant integer (got " +
args[0].getTypeName() + " instead).");
}
numRows =
((WritableConstantIntObjectInspector)args[0]).getWritableConstantValue();
if (numRows == null || numRows.get() < 1) {
throw new UDFArgumentException(
"STACK() expects its first argument to be >= 1.");
}
// Divide and round up.
numCols = (args.length - 1 + numRows.get() - 1) / numRows.get();
for (int jj = 0; jj < numCols; ++jj) {
returnOIResolvers.add(new ReturnObjectInspectorResolver());
for (int ii = 0; ii < numRows.get(); ++ii) {
int index = ii * numCols + jj + 1;
if (index < args.length &&
!returnOIResolvers.get(jj).update(args[index])) {
throw new UDFArgumentException(
"Argument " + (jj + 1) + "'s type (" +
args[jj + 1].getTypeName() + ") should be equal to argument " +
index + "'s type (" + args[index].getTypeName() + ")");
}
}
}
forwardObj = new Object[numCols];
for (int ii = 0; ii < args.length; ++ii) {
argOIs.add(args[ii]);
}
ArrayList<String> fieldNames = new ArrayList<String>();
ArrayList<ObjectInspector> fieldOIs = new ArrayList<ObjectInspector>();
for (int ii = 0; ii < numCols; ++ii) {
fieldNames.add("col" + ii);
fieldOIs.add(returnOIResolvers.get(ii).get());
}
return ObjectInspectorFactory.getStandardStructObjectInspector(
fieldNames, fieldOIs);
}
@Override
public void process(Object[] args)
throws HiveException, UDFArgumentException {
for (int ii = 0; ii < numRows.get(); ++ii) {
for (int jj = 0; jj < numCols; ++jj) {
int index = ii * numCols + jj + 1;
if (index < args.length) {
forwardObj[jj] =
returnOIResolvers.get(jj).convertIfNecessary(args[index], argOIs.get(index));
} else {
forwardObj[ii] = null;
}
}
forward(forwardObj);
}
}
@Override
public String toString() {
return "stack";
}
}