LogicalSubQueryAliasToLogicalProject.java

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package org.apache.doris.nereids.rules.analysis;

import org.apache.doris.nereids.rules.Rule;
import org.apache.doris.nereids.rules.RuleType;
import org.apache.doris.nereids.rules.rewrite.OneRewriteRuleFactory;
import org.apache.doris.nereids.trees.plans.Plan;
import org.apache.doris.nereids.trees.plans.logical.LogicalCatalogRelation;
import org.apache.doris.nereids.trees.plans.logical.LogicalProject;
import org.apache.doris.nereids.util.Utils;

/**
 * Eliminate the logical sub query and alias node after analyze and before rewrite
 * If we match the alias node and return its child node, in the execute() of the job
 * <p>
 * TODO: refactor group merge strategy to support the feature above
 */
public class LogicalSubQueryAliasToLogicalProject extends OneRewriteRuleFactory {
    @Override
    public Rule build() {
        return RuleType.LOGICAL_SUB_QUERY_ALIAS_TO_LOGICAL_PROJECT.build(
                    logicalSubQueryAlias().then(subQueryAlias -> {
                        Plan child = subQueryAlias.child();
                        String alias = subQueryAlias.getAlias();

                        // If child is a LogicalCatalogRelation, set the tableAlias
                        if (child instanceof LogicalCatalogRelation) {
                            child = ((LogicalCatalogRelation) child).withTableAlias(alias);
                        }

                        return new LogicalProject<>(
                                    Utils.fastToImmutableList(subQueryAlias.getOutput()), child);
                    }));
    }
}