org.apache.lens.cube.parse.LightestFactResolver.java Source code

Introduction

Here is the source code for org.apache.lens.cube.parse.LightestFactResolver.java

Source

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.lens.cube.parse;

import java.util.*;

import org.apache.lens.cube.parse.CandidateTablePruneCause.CandidateTablePruneCode;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hive.ql.parse.SemanticException;

/**
 * Prune fact tables having more weight than minimum.
 */
public class LightestFactResolver implements ContextRewriter {
    public static final Log LOG = LogFactory.getLog(LightestFactResolver.class.getName());

    public LightestFactResolver(Configuration conf) {
    }

    @Override
    public void rewriteContext(CubeQueryContext cubeql) throws SemanticException {
        if (cubeql.getCube() != null && !cubeql.getCandidateFactSets().isEmpty()) {
            Map<Set<CandidateFact>, Double> factWeightMap = new HashMap<Set<CandidateFact>, Double>();

            for (Set<CandidateFact> facts : cubeql.getCandidateFactSets()) {
                factWeightMap.put(facts, getWeight(facts));
            }

            double minWeight = Collections.min(factWeightMap.values());

            for (Iterator<Set<CandidateFact>> i = cubeql.getCandidateFactSets().iterator(); i.hasNext();) {
                Set<CandidateFact> facts = i.next();
                if (factWeightMap.get(facts) > minWeight) {
                    LOG.info("Not considering facts:" + facts
                            + " from candidate fact tables as it has more fact weight:" + factWeightMap.get(facts)
                            + " minimum:" + minWeight);
                    i.remove();
                }
            }
            cubeql.pruneCandidateFactWithCandidateSet(CandidateTablePruneCode.MORE_WEIGHT);
        }
    }

    private Double getWeight(Set<CandidateFact> set) {
        Double weight = 0.0;
        for (CandidateFact f : set) {
            weight += f.fact.weight();
        }
        return weight;
    }
}