924060929 commented on code in PR #69093: URL: https://github.com/apache/doris/pull/69093#discussion_r4439965509
########## fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/DecimalMultiplyForSum.java: ########## @@ -0,0 +1,62 @@ +// 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.doris.nereids.trees.expressions; + +import org.apache.doris.analysis.ArithmeticExpr.Operator; +import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor; +import org.apache.doris.nereids.types.DecimalV3Type; + +import com.google.common.base.Preconditions; +import com.google.common.collect.ImmutableList; + +import java.util.List; + +/** + * Restore SUM's join multiplicity without reducing its decimal scale. Unlike ordinary + * multiplication, multiplying a partial sum by an integer count must preserve SUM's type. + * Keep this separate from Multiply so arithmetic simplification cannot rebuild it with + * the ordinary decimal overflow-scale rules. BE executes the existing multiply function. + */ +public class DecimalMultiplyForSum extends BinaryArithmetic { + public DecimalMultiplyForSum(Expression sum, Expression count) { + super(ImmutableList.of(sum, count), Operator.MULTIPLY); + } + + @Override + public Expression withChildren(List<Expression> children) { + Preconditions.checkArgument(children.size() == 2); + return new DecimalMultiplyForSum(children.get(0), children.get(1)); + } + + @Override + public DecimalV3Type getDataTypeForDecimalV3(DecimalV3Type sumType, DecimalV3Type countType) { + Preconditions.checkArgument(countType.getScale() == 0); + return sumType; Review Comment: [P2] Preserve intermediate range until the final SUM With eager_aggregation_mode=1, enable_decimal256=false, check_overflow_for_decimal=true and decimal_overflow_scale=6, consider l(g,k,v DECIMAL(38,18)) containing (G,a,+60000000000000000000) and (G,b,-60000000000000000000), and r(k,w) containing two rows with w=1 for each key. `SELECT l.g,SUM(l.v),SUM(r.w) FROM l JOIN [shuffle] r ON l.k=r.k GROUP BY l.g` should sum to zero. Returning sumType makes each compensation product ±120000000000000000000 undergo the DECIMAL(38,18) range check in BE multiply.cpp:487, throwing before cancellation in the final aggregate. The products still fit Int128; the merge-base multiplication rescales to DECIMAL(38,6) and this case can complete. Preserve sufficient intermediate range through aggregation, or decline the rewrite when that cannot be guaranteed, and add a cancellation regression. This is a static finding; no tests were run. -- 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] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
