CostCalculator.java

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package org.apache.doris.nereids.cost;

import org.apache.doris.nereids.PlanContext;
import org.apache.doris.nereids.memo.GroupExpression;
import org.apache.doris.nereids.properties.DistributionSpecReplicated;
import org.apache.doris.nereids.properties.PhysicalProperties;
import org.apache.doris.nereids.trees.plans.Plan;
import org.apache.doris.qe.ConnectContext;
import org.apache.doris.qe.SessionVariable;

import java.util.List;

/**
 * Calculate the cost of a plan.
 */
// TODO: memory cost and network cost should be estimated by byte size.
public class CostCalculator {

    /**
     * Calculate cost for groupExpression
     */
    public static Cost calculateCost(ConnectContext connectContext, GroupExpression groupExpression,
            List<PhysicalProperties> childrenProperties) {
        PlanContext planContext = new PlanContext(connectContext, groupExpression);
        if (childrenProperties.size() >= 2
                && childrenProperties.get(1).getDistributionSpec() instanceof DistributionSpecReplicated) {
            planContext.setBroadcastJoin();
        }

        CostModelV1 costModelV1 = new CostModelV1(connectContext);
        return groupExpression.getPlan().accept(costModelV1, planContext);
    }

    public static Cost addChildCost(ConnectContext connectContext, Plan plan, Cost planCost, Cost childCost,
            int index) {
        SessionVariable sessionVariable = connectContext.getSessionVariable();
        if (sessionVariable.getEnableNewCostModel()) {
            return CostModelV2.addChildCost(plan, planCost, childCost, index);
        }
        return CostModelV1.addChildCost(sessionVariable, planCost, childCost);
    }
}