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[enhancement](nereids)simplify OneRowRelation scalar subquery (#32276)

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select count() from t where dt > (select '2024-02-02 00:00:00');
-->
select count() from t where dt > '2024-02-02 00:00:00';
This commit is contained in:
starocean999
2024-03-18 12:08:06 +08:00
committed by yiguolei
parent 163007a665
commit fab48f54b1
2 changed files with 33 additions and 0 deletions
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17
fe/fe-core/src/main/java/org/apache/doris/nereids/rules/analysis/SubExprAnalyzer.java
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@ -20,6 +20,7 @@ package org.apache.doris.nereids.rules.analysis;
import org.apache.doris.nereids.CascadesContext;
import org.apache.doris.nereids.analyzer.Scope;
import org.apache.doris.nereids.exceptions.AnalysisException;
import org.apache.doris.nereids.trees.expressions.Alias;
import org.apache.doris.nereids.trees.expressions.Exists;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.InSubquery;
@ -33,7 +34,9 @@ import org.apache.doris.nereids.trees.expressions.visitor.DefaultExpressionRewri
import org.apache.doris.nereids.trees.plans.Plan;
import org.apache.doris.nereids.trees.plans.logical.LogicalAggregate;
import org.apache.doris.nereids.trees.plans.logical.LogicalLimit;
import org.apache.doris.nereids.trees.plans.logical.LogicalOneRowRelation;
import org.apache.doris.nereids.trees.plans.logical.LogicalPlan;
import org.apache.doris.nereids.trees.plans.logical.LogicalProject;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
@ -106,6 +109,20 @@ class SubExprAnalyzer<T> extends DefaultExpressionRewriter<T> {
checkHasAgg(analyzedResult);
checkHasNoGroupBy(analyzedResult);
// if scalar subquery is like select '2024-02-02 00:00:00'
// we can just return the constant expr '2024-02-02 00:00:00'
if (analyzedResult.getLogicalPlan() instanceof LogicalProject) {
LogicalProject project = (LogicalProject) analyzedResult.getLogicalPlan();
if (project.child() instanceof LogicalOneRowRelation
&& project.getProjects().size() == 1
&& project.getProjects().get(0) instanceof Alias) {
Alias alias = (Alias) project.getProjects().get(0);
if (alias.isConstant()) {
return alias.child();
}
}
}
return new ScalarSubquery(analyzedResult.getLogicalPlan(), analyzedResult.getCorrelatedSlots());
}