io.druid.query.groupby.epinephelinae.column.DictionaryBuildingStringGroupByColumnSelectorStrategy Maven / Gradle / Ivy
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* Licensed to Metamarkets Group Inc. (Metamarkets) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. Metamarkets 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 io.druid.query.groupby.epinephelinae.column;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import io.druid.segment.ColumnValueSelector;
import io.druid.segment.DimensionSelector;
import io.druid.segment.data.ArrayBasedIndexedInts;
import io.druid.segment.data.IndexedInts;
import it.unimi.dsi.fastutil.objects.Object2IntOpenHashMap;
import java.nio.ByteBuffer;
import java.util.List;
import java.util.Map;
/**
* A String strategy that builds an internal String<->Integer dictionary for
* DimensionSelectors that return false for nameLookupPossibleInAdvance()
*/
public class DictionaryBuildingStringGroupByColumnSelectorStrategy extends StringGroupByColumnSelectorStrategy
{
private static final int GROUP_BY_MISSING_VALUE = -1;
private int nextId = 0;
private final List dictionary = Lists.newArrayList();
private final Object2IntOpenHashMap reverseDictionary = new Object2IntOpenHashMap<>();
{
reverseDictionary.defaultReturnValue(-1);
}
@Override
public void processValueFromGroupingKey(GroupByColumnSelectorPlus selectorPlus, ByteBuffer key, Map resultMap)
{
final int id = key.getInt(selectorPlus.getKeyBufferPosition());
// GROUP_BY_MISSING_VALUE is used to indicate empty rows, which are omitted from the result map.
if (id != GROUP_BY_MISSING_VALUE) {
final String value = dictionary.get(id);
resultMap.put(
selectorPlus.getOutputName(),
value
);
} else {
resultMap.put(selectorPlus.getOutputName(), "");
}
}
@Override
public void initColumnValues(ColumnValueSelector selector, int columnIndex, Object[] valuess)
{
final DimensionSelector dimSelector = (DimensionSelector) selector;
final IndexedInts row = dimSelector.getRow();
final int[] newIds = new int[row.size()];
for (int i = 0; i < row.size(); i++) {
final String value = dimSelector.lookupName(row.get(i));
final int dictId = reverseDictionary.getInt(value);
if (dictId < 0) {
dictionary.add(value);
reverseDictionary.put(value, nextId);
newIds[i] = nextId;
nextId++;
} else {
newIds[i] = dictId;
}
}
valuess[columnIndex] = ArrayBasedIndexedInts.of(newIds);
}
@Override
public Object getOnlyValue(ColumnValueSelector selector)
{
final DimensionSelector dimSelector = (DimensionSelector) selector;
final IndexedInts row = dimSelector.getRow();
Preconditions.checkState(row.size() < 2, "Not supported for multi-value dimensions");
if (row.size() == 0) {
return GROUP_BY_MISSING_VALUE;
}
final String value = dimSelector.lookupName(row.get(0));
final int dictId = reverseDictionary.getInt(value);
if (dictId < 0) {
dictionary.add(value);
reverseDictionary.put(value, nextId);
return nextId++;
} else {
return dictId;
}
}
}