luoyuxia commented on code in PR #21596: URL: https://github.com/apache/flink/pull/21596#discussion_r1069363291
########## flink-connectors/flink-connector-hive/src/main/java/org/apache/flink/table/functions/hive/HiveCountAggFunction.java: ########## @@ -0,0 +1,116 @@ +/* + * 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.flink.table.functions.hive; + +import org.apache.flink.table.api.DataTypes; +import org.apache.flink.table.api.TableException; +import org.apache.flink.table.expressions.Expression; +import org.apache.flink.table.expressions.UnresolvedReferenceExpression; +import org.apache.flink.table.planner.expressions.ExpressionBuilder; +import org.apache.flink.table.types.DataType; +import org.apache.flink.table.types.inference.CallContext; + +import java.util.ArrayList; +import java.util.List; + +import static org.apache.flink.table.expressions.ApiExpressionUtils.unresolvedRef; +import static org.apache.flink.table.planner.expressions.ExpressionBuilder.ifThenElse; +import static org.apache.flink.table.planner.expressions.ExpressionBuilder.literal; +import static org.apache.flink.table.planner.expressions.ExpressionBuilder.plus; + +/** built-in hive count aggregate function. */ +public class HiveCountAggFunction extends HiveDeclarativeAggregateFunction { + + private final UnresolvedReferenceExpression count = unresolvedRef("count"); + private Integer arguments; + private boolean count1; + + @Override + public int operandCount() { + return arguments; + } + + @Override + public UnresolvedReferenceExpression[] aggBufferAttributes() { + return new UnresolvedReferenceExpression[] {count}; + } + + @Override + public DataType[] getAggBufferTypes() { + return new DataType[] {DataTypes.BIGINT()}; + } + + @Override + public DataType getResultType() { + return DataTypes.BIGINT(); + } + + @Override + public Expression[] initialValuesExpressions() { + return new Expression[] {/* count = */ literal(0L, getResultType().notNull())}; + } + + @Override + public Expression[] accumulateExpressions() { + // count(*) and count(1) mean that count all elements + if (arguments == 0 || count1) { + return new Expression[] {/* count = */ plus(count, literal(1L))}; + } + + // other case need to determine the value of the element + List<Expression> operandExpressions = new ArrayList<>(); + for (int i = 0; i < arguments; i++) { + operandExpressions.add(operand(i)); + } + Expression operandExpression = + operandExpressions.stream() + .map(ExpressionBuilder::isNull) + .reduce(ExpressionBuilder::or) + .get(); + return new Expression[] { + /* count = */ ifThenElse(operandExpression, count, plus(count, literal(1L))) + }; + } + + @Override + public Expression[] retractExpressions() { + throw new TableException("Count aggregate function does not support retraction."); + } + + @Override + public Expression[] mergeExpressions() { + return new Expression[] {/* count = */ plus(count, mergeOperand(count))}; + } + + @Override + public Expression getValueExpression() { + return count; + } + + @Override + public void setArguments(CallContext callContext) { + if (arguments == null) { + arguments = callContext.getArgumentDataTypes().size(); + if (arguments == 1) { + // If the argument is literal 1 indicates use count(1) Review Comment: It may be `count(2)`,`count(3)`..., not always 1. May be we can optimize the comment as follows? ```suggestion // If the argument is literal, indicates use count(literal) ``` If so, the varaible may also need changes. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
