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[feature](Nereids): Convert topn(x, 1) to max(x) (#26004)

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jakevin
2023-10-27 18:45:21 +08:00
committed by GitHub
parent 3beba1764c
commit d953e5c8f4
5 changed files with 155 additions and 1 deletions
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4
fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/ExpressionOptimization.java
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@ -26,6 +26,7 @@ import org.apache.doris.nereids.rules.expression.rules.SimplifyComparisonPredica
import org.apache.doris.nereids.rules.expression.rules.SimplifyDecimalV3Comparison;
import org.apache.doris.nereids.rules.expression.rules.SimplifyInPredicate;
import org.apache.doris.nereids.rules.expression.rules.SimplifyRange;
import org.apache.doris.nereids.rules.expression.rules.TopnToMax;
import com.google.common.collect.ImmutableList;
@ -44,7 +45,8 @@ public class ExpressionOptimization extends ExpressionRewrite {
SimplifyRange.INSTANCE,
OrToIn.INSTANCE,
ArrayContainToArrayOverlap.INSTANCE,
CaseWhenToIf.INSTANCE
CaseWhenToIf.INSTANCE,
TopnToMax.INSTANCE
);
private static final ExpressionRuleExecutor EXECUTOR = new ExpressionRuleExecutor(OPTIMIZE_REWRITE_RULES);

55
fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/TopnToMax.java Normal file
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@ -0,0 +1,55 @@
// 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.rules.expression.rules;
import org.apache.doris.nereids.rules.expression.ExpressionRewriteContext;
import org.apache.doris.nereids.rules.expression.ExpressionRewriteRule;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.agg.AggregateFunction;
import org.apache.doris.nereids.trees.expressions.functions.agg.Max;
import org.apache.doris.nereids.trees.expressions.functions.agg.TopN;
import org.apache.doris.nereids.trees.expressions.literal.IntegerLikeLiteral;
import org.apache.doris.nereids.trees.expressions.visitor.DefaultExpressionRewriter;
/**
* Convert topn(x, 1) to max(x)
*/
public class TopnToMax extends DefaultExpressionRewriter<ExpressionRewriteContext> implements
ExpressionRewriteRule<ExpressionRewriteContext> {
public static final TopnToMax INSTANCE = new TopnToMax();
@Override
public Expression rewrite(Expression expr, ExpressionRewriteContext ctx) {
return expr.accept(this, null);
}
@Override
public Expression visitAggregateFunction(AggregateFunction aggregateFunction, ExpressionRewriteContext context) {
if (!(aggregateFunction instanceof TopN)) {
return aggregateFunction;
}
TopN topN = (TopN) aggregateFunction;
if (topN.arity() == 2 && topN.child(1) instanceof IntegerLikeLiteral
&& ((IntegerLikeLiteral) topN.child(1)).getIntValue() == 1) {
return new Max(topN.child(0));
} else {
return aggregateFunction;
}
}
}