gianm commented on code in PR #19793: URL: https://github.com/apache/druid/pull/19793#discussion_r3686960195
########## processing/src/main/java/org/apache/druid/segment/index/ConstantColumnIndexSupplier.java: ########## @@ -0,0 +1,237 @@ +/* + * 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.index; + +import org.apache.druid.collections.bitmap.BitmapFactory; +import org.apache.druid.error.DruidException; +import org.apache.druid.math.expr.ExprEval; +import org.apache.druid.math.expr.ExpressionType; +import org.apache.druid.query.filter.DruidDoublePredicate; +import org.apache.druid.query.filter.DruidFloatPredicate; +import org.apache.druid.query.filter.DruidLongPredicate; +import org.apache.druid.query.filter.DruidPredicateFactory; +import org.apache.druid.query.filter.DruidPredicateMatch; +import org.apache.druid.segment.column.ColumnIndexSupplier; +import org.apache.druid.segment.column.ColumnType; +import org.apache.druid.segment.column.TypeSignature; +import org.apache.druid.segment.column.ValueType; +import org.apache.druid.segment.index.semantic.DruidPredicateIndexes; +import org.apache.druid.segment.index.semantic.NullValueIndex; +import org.apache.druid.segment.index.semantic.ValueIndexes; +import org.apache.druid.segment.index.semantic.ValueSetIndexes; + +import javax.annotation.Nonnull; +import javax.annotation.Nullable; +import java.util.Collections; +import java.util.List; + +/** + * Index supplier for a primitive column whose value is the same for every row. All indexes produced by this class + * are either {@link AllTrueBitmapColumnIndex}, {@link AllFalseBitmapColumnIndex}, + * or {@link AllUnknownBitmapColumnIndex}. + */ +public class ConstantColumnIndexSupplier implements ColumnIndexSupplier +{ + /** + * The constant value, normalized to {@link #type}. + */ + @Nullable + private final Object value; + + /** + * Type of {@link #value}. + */ + private final ColumnType type; + + /** + * Expression type equivalent of {@link #type}. + */ + private final ExpressionType exprType; + + private final int numRows; + private final BitmapFactory bitmapFactory; + + public ConstantColumnIndexSupplier( + final ColumnType type, + @Nullable final Object value, + final int numRows, + final BitmapFactory bitmapFactory + ) + { + if (!type.is(ValueType.STRING) && !type.isNumeric()) { + throw DruidException.defensive("Cannot handle type[%s]", type); + } + this.type = type; + this.numRows = numRows; + this.bitmapFactory = bitmapFactory; + this.exprType = ExpressionType.fromColumnTypeStrict(type); + + // Normalize the value to the expected type. + final ExprEval<?> constant = ExprEval.bestEffortOf(value).castTo(exprType); + if (constant.value() == null) { + this.value = null; + } else { + // FLOAT has no ExpressionType of its own, so explicitly narrow it back down. + this.value = type.is(ValueType.FLOAT) ? (float) constant.asDouble() : constant.value(); + } + } + + @Nullable + @Override + @SuppressWarnings("unchecked") + public <T> T as(Class<T> clazz) + { + if (clazz.equals(NullValueIndex.class)) { + final BitmapColumnIndex nullIndex = value == null ? allTrue() : allFalse(); + return (T) (NullValueIndex) () -> nullIndex; + } else if (clazz.equals(ValueIndexes.class)) { + return (T) new ConstantValueIndexes(); + } else if (clazz.equals(ValueSetIndexes.class)) { + return (T) new ConstantValueSetIndexes(); + } else if (clazz.equals(DruidPredicateIndexes.class)) { + return (T) new ConstantDruidPredicateIndexes(); + } + return null; + } + + private BitmapColumnIndex allTrue() + { + return new AllTrueBitmapColumnIndex(bitmapFactory, numRows); + } + + private BitmapColumnIndex allFalse() + { + return new AllFalseBitmapColumnIndex(bitmapFactory); + } + + private BitmapColumnIndex allUnknown() + { + return new AllUnknownBitmapColumnIndex(bitmapFactory, numRows); + } + + /** + * Whether some incoming value is equal to {@link #value}. + */ + private boolean matchesConstant(@Nullable Object matchValue, TypeSignature<ValueType> matchValueType) + { + if (matchValue == null) { + return value == null; + } + if (value == null) { + return false; + } + final ExprEval<?> eval = ExprEval.ofType(ExpressionType.fromColumnTypeStrict(matchValueType), matchValue); + final ExprEval<?> castForComparison = ExprEval.castForEqualityComparison(eval, exprType); + if (castForComparison == null || castForComparison.value() == null) { + return false; + } + return switch (type.getType()) { + case STRING -> value.equals(castForComparison.asString()); + case LONG -> (Long) value == castForComparison.asLong(); + // compare bits instead of == to canonicalize NaN + case FLOAT -> Float.floatToIntBits((Float) value) == Float.floatToIntBits((float) castForComparison.asDouble()); + case DOUBLE -> Double.doubleToLongBits((Double) value) == Double.doubleToLongBits(castForComparison.asDouble()); + default -> throw DruidException.defensive("Cannot match values for type[%s]", type); + }; + } + + private class ConstantValueIndexes implements ValueIndexes + { + @Nullable + @Override + public BitmapColumnIndex forValue(@Nonnull Object matchValue, TypeSignature<ValueType> matchValueType) + { + if (!matchValueType.isPrimitive()) { + return null; + } else if (value == null) { + return allUnknown(); + } else { + return matchesConstant(matchValue, matchValueType) ? allTrue() : allFalse(); + } + } + } + + private class ConstantValueSetIndexes implements ValueSetIndexes + { + @Nullable + @Override + public BitmapColumnIndex forSortedValues(@Nonnull List<?> sortedValues, TypeSignature<ValueType> matchValueType) + { + if (!matchValueType.isPrimitive()) { + return null; + } + + if (sortedValues.isEmpty()) { + return allFalse(); + } + + if (matchValueType.getType() == type.getType()) { + if (Collections.binarySearch(sortedValues, value, matchValueType.getNullableStrategy()) >= 0) { + return allTrue(); + } + } else { + for (final Object matchValue : sortedValues) { + if (matchesConstant(matchValue, matchValueType)) { Review Comment: https://github.com/apache/druid/pull/19834 -- This is an automated message from the Apache Git Service. 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