| /** |
| * 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.tajo.engine.function.window; |
| |
| import org.apache.tajo.catalog.Column; |
| import org.apache.tajo.common.TajoDataTypes.Type; |
| import org.apache.tajo.datum.Datum; |
| import org.apache.tajo.datum.DatumFactory; |
| import org.apache.tajo.datum.Int8Datum; |
| import org.apache.tajo.engine.function.FunctionContext; |
| import org.apache.tajo.engine.function.WindowAggFunc; |
| import org.apache.tajo.engine.function.annotation.Description; |
| import org.apache.tajo.engine.function.annotation.ParamTypes; |
| import org.apache.tajo.storage.Tuple; |
| |
| @Description( |
| functionName = "row_number", |
| description = "the total number of retrieved rows", |
| example = "> SELECT row_number() OVER ();", |
| returnType = Type.INT8, |
| paramTypes = {@ParamTypes(paramTypes = {})} |
| ) |
| public class RowNumber extends WindowAggFunc<Datum> { |
| |
| public RowNumber() { |
| super(NoArgs); |
| } |
| |
| protected RowNumber(Column[] columns) { |
| super(columns); |
| } |
| |
| @Override |
| public FunctionContext newContext() { |
| return new RowNumberContext(); |
| } |
| |
| @Override |
| public void eval(FunctionContext ctx, Tuple params) { |
| ((RowNumberContext) ctx).count++; |
| } |
| |
| @Override |
| public Int8Datum terminate(FunctionContext ctx) { |
| return DatumFactory.createInt8(((RowNumberContext) ctx).count); |
| } |
| |
| protected class RowNumberContext implements FunctionContext { |
| long count = 0; |
| } |
| } |