org.apache.hadoop.hive.ql.udf.generic.GenericUDFLead Maven / Gradle / Ivy
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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.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.UDFType;
@Description(
name = "lead",
value = "LEAD (scalar_expression [,offset] [,default]) OVER ([query_partition_clause] order_by_clause); "
+ "The LEAD function is used to return data from the next row. ",
extended = "Example:\n "
+ "select p_name, p_retailprice, lead(p_retailprice) over() as l1,\n"
+ " lag(p_retailprice) over() as l2\n"
+ " from part\n"
+ " where p_retailprice = 1173.15")
@UDFType(impliesOrder = true)
public class GenericUDFLead extends GenericUDFLeadLag {
@Override
protected String _getFnName() {
return "lead";
}
@Override
protected int getIndex(int amt) {
return pItr.getIndex() - 1 + amt;
}
@Override
protected Object getRow(int amt) throws HiveException {
return pItr.lead(amt - 1);
}
}