io.druid.segment.ColumnSelectorFactory Maven / Gradle / Ivy
/*
* 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.segment;
import io.druid.query.dimension.DimensionSpec;
import io.druid.segment.column.ColumnCapabilities;
import javax.annotation.Nullable;
/**
* Factory class for MetricSelectors
*/
public interface ColumnSelectorFactory
{
DimensionSelector makeDimensionSelector(DimensionSpec dimensionSpec);
FloatColumnSelector makeFloatColumnSelector(String columnName);
LongColumnSelector makeLongColumnSelector(String columnName);
DoubleColumnSelector makeDoubleColumnSelector(String columnName);
@Nullable
ObjectColumnSelector makeObjectColumnSelector(String columnName);
/**
* Returns capabilities of a particular column, if known. May be null if the column doesn't exist, or if
* the column does exist but the capabilities are unknown. The latter is possible with dynamically discovered
* columns.
*
* @param column column name
*
* @return capabilities, or null
*/
@Nullable
ColumnCapabilities getColumnCapabilities(String column);
}