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Neo4j Graph Data Science :: Cypher Projection

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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.gds.legacycypherprojection;

import org.neo4j.gds.PropertyMapping;
import org.neo4j.gds.annotation.ValueClass;
import org.neo4j.gds.transaction.TransactionContext;

import java.util.ArrayList;
import java.util.Collection;

import static org.neo4j.gds.utils.StringFormatting.formatWithLocale;

public class CypherQueryEstimator {

    private final TransactionContext context;

    public CypherQueryEstimator(TransactionContext context) {this.context = context;}


    public EstimationResult getNodeEstimation(String nodeQuery) {
        return runEstimationQuery(nodeQuery, NodeSubscriber.RESERVED_COLUMNS);
    }

    public EstimationResult getRelationshipEstimation(String relationshipQuery) {
        return runEstimationQuery(
            relationshipQuery,
            RelationshipSubscriber.RESERVED_COLUMNS
        );
    }

    private EstimationResult runEstimationQuery(String query, Collection reservedColumns) {
        return context.apply((tx, ktx) -> {
            var explainQuery = formatWithLocale("EXPLAIN %s", query);
            try (var result = tx.execute(explainQuery)) {
                var estimatedRows = (Number) result.getExecutionPlanDescription().getArguments().get("EstimatedRows");

                var propertyColumns = new ArrayList<>(result.columns());
                propertyColumns.removeAll(reservedColumns);

                propertyColumns.forEach(PropertyMapping::validatePropertyKey);

                return ImmutableEstimationResult.of(estimatedRows.longValue(), propertyColumns.size());
            }
        });
    }

    @ValueClass
    public
    interface EstimationResult {
        long estimatedRows();

        long propertyCount();
    }
}