RemoveUselessProjectPostProcessor.java

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// to you under the Apache License, Version 2.0 (the
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//
//   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.doris.nereids.processor.post;

import org.apache.doris.nereids.CascadesContext;
import org.apache.doris.nereids.annotation.DependsRules;
import org.apache.doris.nereids.trees.expressions.Slot;
import org.apache.doris.nereids.trees.plans.Plan;
import org.apache.doris.nereids.trees.plans.physical.PhysicalProject;

import org.roaringbitmap.RoaringBitmap;

/**
 * Prune column for Join-Cluster
 */
@DependsRules({
        MergeProjectPostProcessor.class
})
public class RemoveUselessProjectPostProcessor extends PlanPostProcessor {
    @Override
    public Plan visitPhysicalProject(PhysicalProject<? extends Plan> project, CascadesContext ctx) {
        project = (PhysicalProject<? extends Plan>) super.visit(project, ctx);
        Plan child = project.child();
        if (project.isAllSlots()) {
            RoaringBitmap usedSlotExprIds = project.getUsedSlotExprIds();
            for (Slot slot : child.getOutput()) {
                if (!usedSlotExprIds.contains(slot.getExprId().asInt())) {
                    return project;
                }
            }
            return child;
        }
        return project;
    }
}