/**
* 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 com.nexr.platform.hive.udf;
import java.util.ArrayList;
import org.apache.commons.lang.StringUtils;
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.UDFType;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters.Converter;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils.ObjectInspectorCopyOption;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils;
import org.apache.hive.pdk.HivePdkUnitTest;
import org.apache.hive.pdk.HivePdkUnitTests;
@Description(name = "lag",
value = "_FUNC_(hash_key,column[,offset[,default]]) " +
"- Returns values from a previous row in the table.",
extended = "Example:\n"
+ " > SELECT _FUNC_(HASH(p1,p2), column [,offset[,default]]) FROM (\n"
+ " > SELECT ~ FROM table DISTRIBUTE BY HASH(p1,p2) SORT BY p1,p2\n"
+ " > );")
@HivePdkUnitTests(
setup = "", cleanup = "",
cases = {
@HivePdkUnitTest(
query = "SELECT t.empno, t.deptno, t.sal, nexr_lag(hash(t.deptno),t.sal) as col"
+" FROM ("
+" select a.empno, a.deptno, a.sal from emp a"
+" distribute by hash(a.deptno)"
+" sort BY a.deptno, a.empno"
+" ) t;",
result =
"7782\t10\t2450\tNULL\n"
+"7839\t10\t5000\t2450\n"
+"7934\t10\t1300\t5000\n"
+"7369\t20\t800\tNULL\n"
+"7566\t20\t2975\t800\n"
+"7788\t20\t3000\t2975\n"
+"7876\t20\t1100\t3000\n"
+"7902\t20\t3000\t1100\n"
+"7499\t30\t1600\tNULL\n"
+"7521\t30\t1250\t1600\n"
+"7654\t30\t1250\t1250\n"
+"7698\t30\t2850\t1250\n"
+"7844\t30\t1500\t2850\n"
+"7900\t30\t950\t1500"),
@HivePdkUnitTest(
query = "SELECT t.empno, t.deptno, t.sal, nexr_lag(hash(t.deptno),t.sal,2,0) as col"
+" FROM ("
+" select a.empno, a.deptno, a.sal from emp a "
+" distribute by hash(a.deptno)"
+" sort BY a.deptno, a.empno"
+" ) t;",
result =
"7782\t10\t2450\t0\n"
+"7839\t10\t5000\t0\n"
+"7934\t10\t1300\t2450\n"
+"7369\t20\t800\t0\n"
+"7566\t20\t2975\t0\n"
+"7788\t20\t3000\t800\n"
+"7876\t20\t1100\t2975\n"
+"7902\t20\t3000\t3000\n"
+"7499\t30\t1600\t0\n"
+"7521\t30\t1250\t0\n"
+"7654\t30\t1250\t1600\n"
+"7698\t30\t2850\t1250\n"
+"7844\t30\t1500\t1250\n"
+"7900\t30\t950\t2850")
}
)
@UDFType(deterministic = false, stateful = true)
public class GenericUDFLag extends GenericUDF {
private ObjectInspector[] argumentOIs;
private ObjectInspector resultOI, prevHashStandardOI, valueStandardOI;
private Object prevHash;
private ArrayList<Object> queue = new ArrayList<Object>();
@Override
public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {
if (arguments.length<2||arguments.length>4) {
throw new UDFArgumentException("The function accepts more than two arguments.");
}
argumentOIs = arguments;
prevHashStandardOI = ObjectInspectorUtils.getStandardObjectInspector(arguments[0],ObjectInspectorCopyOption.JAVA);
valueStandardOI = ObjectInspectorUtils.getStandardObjectInspector(arguments[1],ObjectInspectorCopyOption.JAVA);
resultOI=arguments[1];
return resultOI;
}
@Override
public Object evaluate(DeferredObject[] arguments) throws HiveException {
Object hash = arguments[0].get();
Object value = arguments[1].get();
int offset=1;
Object defaultValue=null;
if (arguments.length>=3)
offset = PrimitiveObjectInspectorUtils.getInt(arguments[2].get(),(PrimitiveObjectInspector)argumentOIs[2]);
if (arguments.length==4)
defaultValue=arguments[3].get();
if (prevHash==null||ObjectInspectorUtils.compare(prevHash,prevHashStandardOI,hash,argumentOIs[0])!=0) {
queue.clear();
}
queue.add(ObjectInspectorUtils.copyToStandardObject(value,argumentOIs[1],ObjectInspectorCopyOption.JAVA));
prevHash=ObjectInspectorUtils.copyToStandardObject(hash, argumentOIs[0],ObjectInspectorCopyOption.JAVA);
if (queue.size()==offset+1) {
Converter converter = ObjectInspectorConverters.getConverter(valueStandardOI, resultOI);
return converter.convert(queue.remove(0));
}
return defaultValue;
}
@Override
public String getDisplayString(String[] children) {
return "lag(" + StringUtils.join(children, ',') + ")";
}
}