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/*
* 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.parquet.column.statistics;
import java.util.Arrays;
import org.apache.parquet.column.UnknownColumnTypeException;
import org.apache.parquet.io.api.Binary;
import org.apache.parquet.schema.PrimitiveComparator;
import org.apache.parquet.schema.PrimitiveStringifier;
import org.apache.parquet.schema.PrimitiveType;
import org.apache.parquet.schema.PrimitiveType.PrimitiveTypeName;
import org.apache.parquet.schema.Type;
/**
* Statistics class to keep track of statistics in parquet pages and column chunks
*
* @param the Java type described by this Statistics instance
*/
public abstract class Statistics> {
/**
* Builder class to build Statistics objects. Used to read the statistics from the Parquet file.
*/
public static class Builder {
private final PrimitiveType type;
private byte[] min;
private byte[] max;
private long numNulls = -1;
private Builder(PrimitiveType type) {
this.type = type;
}
public Builder withMin(byte[] min) {
this.min = min;
return this;
}
public Builder withMax(byte[] max) {
this.max = max;
return this;
}
public Builder withNumNulls(long numNulls) {
this.numNulls = numNulls;
return this;
}
public Statistics build() {
Statistics stats = createStats(type);
if (min != null && max != null) {
stats.setMinMaxFromBytes(min, max);
}
stats.num_nulls = this.numNulls;
return stats;
}
}
// Builder for FLOAT type to handle special cases of min/max values like NaN, -0.0, and 0.0
private static class FloatBuilder extends Builder {
public FloatBuilder(PrimitiveType type) {
super(type);
assert type.getPrimitiveTypeName() == PrimitiveTypeName.FLOAT;
}
@Override
public Statistics build() {
FloatStatistics stats = (FloatStatistics) super.build();
if (stats.hasNonNullValue()) {
Float min = stats.genericGetMin();
Float max = stats.genericGetMax();
// Drop min/max values in case of NaN as the sorting order of values is undefined for this case
if (min.isNaN() || max.isNaN()) {
stats.setMinMax(0.0f, 0.0f);
((Statistics) stats).hasNonNullValue = false;
} else {
// Updating min to -0.0 and max to +0.0 to ensure that no 0.0 values would be skipped
if (Float.compare(min, 0.0f) == 0) {
min = -0.0f;
stats.setMinMax(min, max);
}
if (Float.compare(max, -0.0f) == 0) {
max = 0.0f;
stats.setMinMax(min, max);
}
}
}
return stats;
}
}
// Builder for DOUBLE type to handle special cases of min/max values like NaN, -0.0, and 0.0
private static class DoubleBuilder extends Builder {
public DoubleBuilder(PrimitiveType type) {
super(type);
assert type.getPrimitiveTypeName() == PrimitiveTypeName.DOUBLE;
}
@Override
public Statistics build() {
DoubleStatistics stats = (DoubleStatistics) super.build();
if (stats.hasNonNullValue()) {
Double min = stats.genericGetMin();
Double max = stats.genericGetMax();
// Drop min/max values in case of NaN as the sorting order of values is undefined for this case
if (min.isNaN() || max.isNaN()) {
stats.setMinMax(0.0, 0.0);
((Statistics) stats).hasNonNullValue = false;
} else {
// Updating min to -0.0 and max to +0.0 to ensure that no 0.0 values would be skipped
if (Double.compare(min, 0.0) == 0) {
min = -0.0;
stats.setMinMax(min, max);
}
if (Double.compare(max, -0.0) == 0) {
max = 0.0;
stats.setMinMax(min, max);
}
}
}
return stats;
}
}
private final PrimitiveType type;
private final PrimitiveComparator comparator;
private boolean hasNonNullValue;
private long num_nulls;
final PrimitiveStringifier stringifier;
Statistics(PrimitiveType type) {
this.type = type;
this.comparator = type.comparator();
this.stringifier = type.stringifier();
hasNonNullValue = false;
num_nulls = 0;
}
/**
* Returns the typed statistics object based on the passed type parameter
* @param type PrimitiveTypeName type of the column
* @return instance of a typed statistics class
* @deprecated Use {@link #createStats(Type)} instead
*/
@Deprecated
public static Statistics getStatsBasedOnType(PrimitiveTypeName type) {
switch (type) {
case INT32:
return new IntStatistics();
case INT64:
return new LongStatistics();
case FLOAT:
return new FloatStatistics();
case DOUBLE:
return new DoubleStatistics();
case BOOLEAN:
return new BooleanStatistics();
case BINARY:
return new BinaryStatistics();
case INT96:
return new BinaryStatistics();
case FIXED_LEN_BYTE_ARRAY:
return new BinaryStatistics();
default:
throw new UnknownColumnTypeException(type);
}
}
/**
* Creates an empty {@code Statistics} instance for the specified type to be
* used for reading/writing the new min/max statistics used in the V2 format.
*
* @param type
* type of the column
* @return instance of a typed statistics class
*/
public static Statistics createStats(Type type) {
PrimitiveType primitive = type.asPrimitiveType();
switch (primitive.getPrimitiveTypeName()) {
case INT32:
return new IntStatistics(primitive);
case INT64:
return new LongStatistics(primitive);
case FLOAT:
return new FloatStatistics(primitive);
case DOUBLE:
return new DoubleStatistics(primitive);
case BOOLEAN:
return new BooleanStatistics(primitive);
case BINARY:
case INT96:
case FIXED_LEN_BYTE_ARRAY:
return new BinaryStatistics(primitive);
default:
throw new UnknownColumnTypeException(primitive.getPrimitiveTypeName());
}
}
/**
* Returns a builder to create new statistics object. Used to read the statistics from the parquet file.
*
* @param type
* type of the column
* @return builder to create new statistics object
*/
public static Builder getBuilderForReading(PrimitiveType type) {
switch (type.getPrimitiveTypeName()) {
case FLOAT:
return new FloatBuilder(type);
case DOUBLE:
return new DoubleBuilder(type);
default:
return new Builder(type);
}
}
/**
* updates statistics min and max using the passed value
* @param value value to use to update min and max
*/
public void updateStats(int value) {
throw new UnsupportedOperationException();
}
/**
* updates statistics min and max using the passed value
* @param value value to use to update min and max
*/
public void updateStats(long value) {
throw new UnsupportedOperationException();
}
/**
* updates statistics min and max using the passed value
* @param value value to use to update min and max
*/
public void updateStats(float value) {
throw new UnsupportedOperationException();
}
/**
* updates statistics min and max using the passed value
* @param value value to use to update min and max
*/
public void updateStats(double value) {
throw new UnsupportedOperationException();
}
/**
* updates statistics min and max using the passed value
* @param value value to use to update min and max
*/
public void updateStats(boolean value) {
throw new UnsupportedOperationException();
}
/**
* updates statistics min and max using the passed value
* @param value value to use to update min and max
*/
public void updateStats(Binary value) {
throw new UnsupportedOperationException();
}
/**
* Equality comparison method to compare two statistics objects.
* @param other Object to compare against
* @return true if objects are equal, false otherwise
*/
@Override
public boolean equals(Object other) {
if (other == this)
return true;
if (!(other instanceof Statistics))
return false;
Statistics stats = (Statistics) other;
return type.equals(stats.type) &&
Arrays.equals(stats.getMaxBytes(), this.getMaxBytes()) &&
Arrays.equals(stats.getMinBytes(), this.getMinBytes()) &&
stats.getNumNulls() == this.getNumNulls();
}
/**
* Hash code for the statistics object
* @return hash code int
*/
@Override
public int hashCode() {
return 31 * type.hashCode() + 31 * Arrays.hashCode(getMaxBytes()) + 17 * Arrays.hashCode(getMinBytes())
+ Long.valueOf(this.getNumNulls()).hashCode();
}
/**
* Method to merge this statistics object with the object passed
* as parameter. Merging keeps the smallest of min values, largest of max
* values and combines the number of null counts.
* @param stats Statistics object to merge with
*/
public void mergeStatistics(Statistics stats) {
if (stats.isEmpty()) return;
// Merge stats only if they have the same type
if (type.equals(stats.type)) {
incrementNumNulls(stats.getNumNulls());
if (stats.hasNonNullValue()) {
mergeStatisticsMinMax(stats);
markAsNotEmpty();
}
} else {
throw StatisticsClassException.create(this, stats);
}
}
/**
* Abstract method to merge this statistics min and max with the values
* of the parameter object. Does not do any checks, only called internally.
* @param stats Statistics object to merge with
*/
abstract protected void mergeStatisticsMinMax(Statistics stats);
/**
* Abstract method to set min and max values from byte arrays.
* @param minBytes byte array to set the min value to
* @param maxBytes byte array to set the max value to
* @deprecated will be removed in 2.0.0. Use {@link #getBuilderForReading(PrimitiveType)} instead.
*/
@Deprecated
abstract public void setMinMaxFromBytes(byte[] minBytes, byte[] maxBytes);
/**
* Returns the min value in the statistics. The java natural order of the returned type defined by {@link
* Comparable#compareTo(Object)} might not be the proper one. For example, UINT_32 requires unsigned comparison instead of the
* natural signed one. Use {@link #compareMinToValue(Comparable)} or the comparator returned by {@link #comparator()} to
* always get the proper ordering.
*
* @return the min value
*/
abstract public T genericGetMin();
/**
* Returns the max value in the statistics. The java natural order of the returned type defined by {@link
* Comparable#compareTo(Object)} might not be the proper one. For example, UINT_32 requires unsigned comparison instead of the
* natural signed one. Use {@link #compareMaxToValue(Comparable)} or the comparator returned by {@link #comparator()} to
* always get the proper ordering.
*
* @return the max value
*/
abstract public T genericGetMax();
/**
* Returns the {@link PrimitiveComparator} implementation to be used to compare two generic values in the proper way
* (for example, unsigned comparison for UINT_32).
*
* @return the comparator for data described by this Statistics instance
*/
public final PrimitiveComparator comparator() {
return comparator;
}
/**
* Compares min to the specified value in the proper way. It does the same as invoking
* {@code comparator().compare(genericGetMin(), value)}. The corresponding statistics implementations overload this
* method so the one with the primitive argument shall be used to avoid boxing/unboxing.
*
* @param value
* the value which {@code min} is to be compared to
* @return a negative integer, zero, or a positive integer as {@code min} is less than, equal to, or greater than
* {@code value}.
*/
public final int compareMinToValue(T value) {
return comparator.compare(genericGetMin(), value);
}
/**
* Compares max to the specified value in the proper way. It does the same as invoking
* {@code comparator().compare(genericGetMax(), value)}. The corresponding statistics implementations overload this
* method so the one with the primitive argument shall be used to avoid boxing/unboxing.
*
* @param value
* the value which {@code max} is to be compared to
* @return a negative integer, zero, or a positive integer as {@code max} is less than, equal to, or greater than
* {@code value}.
*/
public final int compareMaxToValue(T value) {
return comparator.compare(genericGetMax(), value);
}
/**
* Abstract method to return the max value as a byte array
* @return byte array corresponding to the max value
*/
abstract public byte[] getMaxBytes();
/**
* Abstract method to return the min value as a byte array
* @return byte array corresponding to the min value
*/
abstract public byte[] getMinBytes();
/**
* Returns the string representation of min for debugging/logging purposes.
*
* @return the min value as a string
*/
public String minAsString() {
return stringify(genericGetMin());
}
/**
* Returns the string representation of max for debugging/logging purposes.
*
* @return the max value as a string
*/
public String maxAsString() {
return stringify(genericGetMax());
}
abstract String stringify(T value);
/**
* Abstract method to return whether the min and max values fit in the given
* size.
* @param size a size in bytes
* @return true iff the min and max values are less than size bytes
*/
abstract public boolean isSmallerThan(long size);
@Override
public String toString() {
if (this.hasNonNullValue()) {
if (isNumNullsSet()) {
return String.format("min: %s, max: %s, num_nulls: %d", minAsString(), maxAsString(), this.getNumNulls());
} else {
return String.format("min: %s, max: %s, num_nulls not defined", minAsString(), maxAsString());
}
} else if (!this.isEmpty())
return String.format("num_nulls: %d, min/max not defined", this.getNumNulls());
else
return "no stats for this column";
}
/**
* Increments the null count by one
*/
public void incrementNumNulls() {
num_nulls++ ;
}
/**
* Increments the null count by the parameter value
* @param increment value to increment the null count by
*/
public void incrementNumNulls(long increment) {
num_nulls += increment ;
}
/**
* Returns the null count
* @return null count or {@code -1} if the null count is not set
*/
public long getNumNulls() {
return num_nulls;
}
/**
* Sets the number of nulls to the parameter value
*
* @param nulls
* null count to set the count to
* @deprecated will be removed in 2.0.0. Use {@link #getBuilderForReading(PrimitiveType)} instead.
*/
@Deprecated
public void setNumNulls(long nulls) {
num_nulls = nulls;
}
/**
* Returns a boolean specifying if the Statistics object is empty,
* i.e does not contain valid statistics for the page/column yet
* @return true if object is empty, false otherwise
*/
public boolean isEmpty() {
return !hasNonNullValue && !isNumNullsSet();
}
/**
* Returns whether there have been non-null values added to this statistics
*
* @return true if the values contained at least one non-null value
*/
public boolean hasNonNullValue() {
return hasNonNullValue;
}
/**
* @return whether numNulls is set and can be used
*/
public boolean isNumNullsSet() {
return num_nulls >= 0;
}
/**
* Sets the page/column as having a valid non-null value
* kind of misnomer here
*/
protected void markAsNotEmpty() {
hasNonNullValue = true;
}
/**
* @return a new independent statistics instance of this class.
*/
public abstract Statistics copy();
/**
* @return the primitive type object which this statistics is created for
*/
public PrimitiveType type() {
return type;
}
}
