| /* |
| * 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.segment.column; |
| |
| import com.fasterxml.jackson.annotation.JsonCreator; |
| import com.fasterxml.jackson.annotation.JsonValue; |
| import org.apache.druid.java.util.common.StringUtils; |
| |
| import javax.annotation.Nullable; |
| |
| /** |
| * This interface is used to expose information about columns that is interesting to know for all matters dealing with |
| * reading from columns, including query planning and optimization, creating readers to merge segments at ingestion |
| * time, and probably nearly anything else you can imagine. |
| */ |
| public interface ColumnCapabilities |
| { |
| /** |
| * Column type, good to know so caller can know what to expect and which optimal selector to use |
| */ |
| ValueType getType(); |
| |
| /** |
| * |
| * If ValueType is COMPLEX, then the typeName associated with it. |
| */ |
| @Nullable |
| String getComplexTypeName(); |
| |
| /** |
| * Is the column dictionary encoded? If so, a DimensionDictionarySelector may be used instead of using a value |
| * selector, allowing algorithms to operate on primitive integer dictionary ids rather than the looked up dictionary |
| * values |
| */ |
| Capable isDictionaryEncoded(); |
| |
| /** |
| * If the column is dictionary encoded, are those values sorted? Useful to know for optimizations that can defer |
| * looking up values and allowing sorting with the dictionary ids directly |
| */ |
| |
| Capable areDictionaryValuesSorted(); |
| |
| /** |
| * If the column is dictionary encoded, is there a 1:1 mapping of dictionary ids to values? If this is true, it |
| * unlocks optimizations such as allowing for things like grouping directly on dictionary ids and deferred value |
| * lookup |
| */ |
| Capable areDictionaryValuesUnique(); |
| |
| /** |
| * String columns are sneaky, and might have multiple values, this is to allow callers to know and appropriately |
| * prepare themselves |
| */ |
| Capable hasMultipleValues(); |
| |
| /** |
| * Does the column have an inverted index bitmap for each value? If so, these may be employed to 'pre-filter' the |
| * column by examining if the values match the filter and intersecting the bitmaps, to avoid having to scan and |
| * evaluate if every row matches the filter |
| */ |
| boolean hasBitmapIndexes(); |
| |
| /** |
| * Does the column have spatial indexes available to allow use with spatial filtering? |
| */ |
| boolean hasSpatialIndexes(); |
| |
| /** |
| * All Druid primitive columns support filtering, maybe with or without indexes, but by default complex columns |
| * do not support direct filtering, unless provided by through a custom implementation. |
| */ |
| boolean isFilterable(); |
| |
| /** |
| * Does this column contain null values? If so, callers, especially for primitive numeric columns, will need to check |
| * for null value rows and act accordingly |
| */ |
| Capable hasNulls(); |
| |
| enum Capable |
| { |
| FALSE, |
| TRUE, |
| UNKNOWN; |
| |
| public boolean isTrue() |
| { |
| return this == TRUE; |
| } |
| |
| public boolean isMaybeTrue() |
| { |
| return isTrue() || isUnknown(); |
| } |
| |
| public boolean isFalse() |
| { |
| return this == FALSE; |
| } |
| |
| public boolean isUnknown() |
| { |
| return this == UNKNOWN; |
| } |
| |
| public Capable coerceUnknownToBoolean(boolean unknownIsTrue) |
| { |
| return this == UNKNOWN ? Capable.of(unknownIsTrue) : this; |
| } |
| |
| public Capable and(Capable other) |
| { |
| if (this == UNKNOWN || other == UNKNOWN) { |
| return UNKNOWN; |
| } |
| return this == TRUE && other == TRUE ? TRUE : FALSE; |
| } |
| |
| public Capable or(Capable other) |
| { |
| if (this == TRUE) { |
| return TRUE; |
| } |
| return other; |
| } |
| |
| public static Capable of(boolean bool) |
| { |
| return bool ? TRUE : FALSE; |
| } |
| |
| @JsonCreator |
| public static Capable ofNullable(@Nullable Boolean bool) |
| { |
| return bool == null ? Capable.UNKNOWN : of(bool); |
| } |
| |
| @JsonValue |
| @Nullable |
| public Boolean toJson() |
| { |
| return this == UNKNOWN ? null : isTrue(); |
| } |
| |
| @Override |
| public String toString() |
| { |
| return StringUtils.toLowerCase(super.toString()); |
| } |
| } |
| |
| /** |
| * This interface define the shape of a mechnism to allow for bespoke coercion of {@link Capable#UNKNOWN} into |
| * {@link Capable#TRUE} or {@link Capable#FALSE} for each {@link Capable} of a {@link ColumnCapabilities}, as is |
| * appropriate for the situation of the caller. |
| */ |
| interface CoercionLogic |
| { |
| /** |
| * If {@link ColumnCapabilities#isDictionaryEncoded()} is {@link Capable#UNKNOWN}, define if it should be treated |
| * as true or false. |
| */ |
| boolean dictionaryEncoded(); |
| |
| /** |
| * If {@link ColumnCapabilities#areDictionaryValuesSorted()} ()} is {@link Capable#UNKNOWN}, define if it should be |
| * treated as true or false. |
| */ |
| boolean dictionaryValuesSorted(); |
| |
| /** |
| * If {@link ColumnCapabilities#areDictionaryValuesUnique()} ()} is {@link Capable#UNKNOWN}, define if it should be |
| * treated as true or false. |
| */ |
| boolean dictionaryValuesUnique(); |
| |
| /** |
| * If {@link ColumnCapabilities#hasMultipleValues()} is {@link Capable#UNKNOWN}, define if it should be treated |
| * as true or false. |
| */ |
| boolean multipleValues(); |
| |
| /** |
| * If {@link ColumnCapabilities#hasNulls()} is {@link Capable#UNKNOWN}, define if it should be treated as true |
| * or false |
| */ |
| boolean hasNulls(); |
| } |
| } |