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

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

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/**
 * 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.metadata.Dimension;
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 dimension tables having more weight than minimum
 */
class LightestDimensionResolver implements ContextRewriter {
    public static final Log LOG = LogFactory.getLog(LightestDimensionResolver.class.getName());

    public LightestDimensionResolver(Configuration conf) {
    }

    @Override
    public void rewriteContext(CubeQueryContext cubeql) throws SemanticException {
        if (!cubeql.getCandidateDimTables().isEmpty()) {
            for (Map.Entry<Dimension, Set<CandidateDim>> entry : cubeql.getCandidateDimTables().entrySet()) {
                if (entry.getValue().isEmpty()) {
                    continue;
                }
                Map<CandidateDim, Double> dimWeightMap = new HashMap<CandidateDim, Double>();

                for (CandidateDim dim : entry.getValue()) {
                    dimWeightMap.put(dim, dim.dimtable.weight());
                }

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

                for (Iterator<CandidateDim> i = entry.getValue().iterator(); i.hasNext();) {
                    CandidateDim dim = i.next();
                    if (dimWeightMap.get(dim) > minWeight) {
                        LOG.info("Not considering dimtable:" + dim
                                + " from candidate dimension tables as it has more weight:" + dimWeightMap.get(dim)
                                + " minimum:" + minWeight);
                        cubeql.addDimPruningMsgs(entry.getKey(), dim.dimtable,
                                new CandidateTablePruneCause(CandidateTablePruneCode.MORE_WEIGHT));
                        i.remove();
                    }
                }
            }
        }
    }
}