| /* |
| * 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.druid.query.topn.types; |
| |
| import com.google.common.base.Preconditions; |
| import org.apache.druid.java.util.common.IAE; |
| import org.apache.druid.query.dimension.ColumnSelectorStrategyFactory; |
| import org.apache.druid.segment.ColumnValueSelector; |
| import org.apache.druid.segment.DimensionHandlerUtils; |
| import org.apache.druid.segment.column.ColumnCapabilities; |
| import org.apache.druid.segment.column.ColumnType; |
| import org.apache.druid.segment.column.ValueType; |
| |
| import java.util.function.Function; |
| |
| public class TopNColumnAggregatesProcessorFactory |
| implements ColumnSelectorStrategyFactory<TopNColumnAggregatesProcessor<?>> |
| { |
| private final ColumnType dimensionType; |
| |
| public TopNColumnAggregatesProcessorFactory(final ColumnType dimensionType) |
| { |
| this.dimensionType = Preconditions.checkNotNull(dimensionType, "dimensionType"); |
| } |
| |
| @Override |
| public TopNColumnAggregatesProcessor<?> makeColumnSelectorStrategy( |
| ColumnCapabilities capabilities, |
| ColumnValueSelector selector, |
| String dimension |
| ) |
| { |
| if (capabilities.is(ValueType.STRING)) { |
| return new StringTopNColumnAggregatesProcessor(capabilities, dimensionType); |
| } else if (capabilities.isNumeric()) { |
| final Function<Object, Object> converter; |
| final ColumnType strategyType; |
| // When the selector is numeric, we want to use NumericTopNColumnSelectorStrategy. It aggregates using |
| // a numeric type and then converts to the desired output type after aggregating. We must be careful not to |
| // convert to an output type that cannot represent all possible values of the input type. |
| if (dimensionType.isNumeric()) { |
| // Return strategy that aggregates using the _output_ type, because this allows us to collapse values |
| // properly (numeric types cannot always represent all values of other numeric types). |
| converter = DimensionHandlerUtils.converterFromTypeToType(dimensionType, dimensionType); |
| strategyType = dimensionType; |
| } else { |
| // Return strategy that aggregates using the _input_ type. Here we are assuming that the output type can |
| // represent all possible values of the input type. This will be true for STRING, which is the only |
| // non-numeric type currently supported. |
| converter = DimensionHandlerUtils.converterFromTypeToType(capabilities, dimensionType); |
| strategyType = capabilities.toColumnType(); |
| } |
| switch (strategyType.getType()) { |
| case LONG: |
| return new LongTopNColumnAggregatesProcessor(converter); |
| case FLOAT: |
| return new FloatTopNColumnAggregatesProcessor(converter); |
| case DOUBLE: |
| return new DoubleTopNColumnAggregatesProcessor(converter); |
| } |
| } |
| |
| throw new IAE("Cannot create query type helper from invalid type [%s]", capabilities.asTypeString()); |
| } |
| |
| @Override |
| public boolean supportsComplexTypes() |
| { |
| return false; |
| } |
| } |