pitrou commented on code in PR #45459: URL: https://github.com/apache/arrow/pull/45459#discussion_r2024526762
########## cpp/src/parquet/geospatial_statistics.h: ########## @@ -0,0 +1,192 @@ +// 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. + +#pragma once + +#include <cmath> +#include <cstdint> +#include <memory> + +#include "parquet/platform.h" +#include "parquet/types.h" + +namespace parquet { + +/// \brief Structure represented encoded statistics to be written to and read from Parquet +/// serialized metadata. +/// +/// See the Parquet Thrift definition and GeoStatistics for the specific definition +/// of field values. +struct PARQUET_EXPORT EncodedGeoStatistics { + static constexpr double kInf = std::numeric_limits<double>::infinity(); + + double xmin{kInf}; + double xmax{-kInf}; + double ymin{kInf}; + double ymax{-kInf}; + double zmin{kInf}; + double zmax{-kInf}; + double mmin{kInf}; + double mmax{-kInf}; + std::vector<int32_t> geospatial_types; + + bool has_x() const { return !std::isinf(xmin - xmax); } + bool has_y() const { return !std::isinf(ymin - ymax); } + bool has_z() const { return !std::isinf(zmin - zmax); } + bool has_m() const { return !std::isinf(mmin - mmax); } + + bool is_set() const { + return !geospatial_types.empty() || has_x() || has_y() || has_z() || has_m(); + } +}; + +class GeoStatisticsImpl; + +/// \brief Base type for computing geospatial column statistics while writing a file +/// or representing them when reading a file +/// +/// Note that NaN values that were encountered within coordinates are omitted; however, +/// NaN values that were obtained via decoding encoded statistics are propagated. This +/// behaviour ensures C++ clients that are inspecting statistics via the column metadata +/// can detect the case where a writer generated NaNs (even though this implementation +/// does not generate them). +/// +/// The handling of NaN values in coordinates is not well-defined among bounding +/// implementations except for the WKB convention for POINT EMPTY, which is consistently +/// represented as a point whose ordinates are all NaN. Any other geometry that contains +/// NaNs cannot expect defined behaviour here or elsewhere; however, a row group that +/// contains both NaN-containing and normal (completely finite) geometries should not be +/// excluded from predicate pushdown. +/// +/// EXPERIMENTAL +class PARQUET_EXPORT GeoStatistics { + public: + GeoStatistics(); + explicit GeoStatistics(const EncodedGeoStatistics& encoded); + + ~GeoStatistics(); + + /// \brief Return true if bounds, geometry types, and validity are identical + bool Equals(const GeoStatistics& other) const; + + /// \brief Update these statistics based on previously calculated or decoded statistics + void Merge(const GeoStatistics& other); + + /// \brief Update these statistics based on values + void Update(const ByteArray* values, int64_t num_values); + + /// \brief Update these statistics based on the non-null elements of values + void UpdateSpaced(const ByteArray* values, const uint8_t* valid_bits, + int64_t valid_bits_offset, int64_t num_spaced_values, + int64_t num_values); + + /// \brief Update these statistics based on the non-null elements of values + /// + /// Currently, BinaryArray and LargeBinaryArray input is supported. + void Update(const ::arrow::Array& values); + + /// \brief Return these statistics to an empty state + void Reset(); + + /// \brief Encode the statistics for serializing to Thrift + /// + /// If invalid WKB was encountered, empty encoded statistics are returned + /// (such that is_set() returns false and they should not be written). + EncodedGeoStatistics Encode() const; + + /// \brief Returns true if all WKB encountered was valid or false otherwise + bool is_valid() const; + + /// \brief Reset existing statistics and populate them from previously-encoded ones + void Decode(const EncodedGeoStatistics& encoded); + + /// \brief The minimum encountered value in the X dimension, or Inf if no non-NaN X + /// values were encountered. + /// + /// The Parquet definition allows for "wrap around" bounds where xmin > xmax. In this + /// case, these bounds represent the union of the intervals [xmax, Inf] and [-Inf, + /// xmin]. This implementation does not yet generate these types of bounds but they may + /// be encountered in files written by other writers. + double xmin() const; + + /// \brief The maximum encountered value in the X dimension, or -Inf if no non-NaN X + /// values were encountered, subject to "wrap around" bounds (see xmin()). + double xmax() const; + + /// \brief The minimum encountered value in the Y dimension, or Inf if no non-NaN Y + /// values were encountered. Wrap around bounds are not permitted in the Y dimension. + double ymin() const; + + /// \brief The maximum encountered value in the Y dimension, or -Inf if no non-NaN Y + /// values were encountered. Wrap around bounds are not permitted in the Y dimension. + double ymax() const; + + /// \brief The minimum encountered value in the Z dimension, or Inf if no non-NaN Z + /// values were encountered. Wrap around bounds are not permitted in the Z dimension. + double zmin() const; + + /// \brief The maximum encountered value in the Z dimension, or -Inf if no non-NaN Z + /// values were encountered. Wrap around bounds are not permitted in the Z dimension. + double zmax() const; + + /// \brief The minimum encountered value in the M dimension, or Inf if no non-NaN M + /// values were encountered. Wrap around bounds are not permitted in the M dimension. + double mmin() const; + + /// \brief The maximum encountered value in the M dimension, or -Inf if no non-NaN M + /// values were encountered. Wrap around bounds are not permitted in the M dimension. + double mmax() const; + + /// \brief All minimum values in XYZM order + std::array<double, 4> lower_bound() const; + + /// \brief All maximum values in XYZM order + std::array<double, 4> upper_bound() const; + + /// \brief Returns true if zero finite coordinates or geometry types were encountered + /// + /// This will occur, for example, if all encountered values were null. If all + /// encountered values were EMPTY (e.g., all values were POINT EMPTY, LINESTRING EMPTY, + /// etc.), is_empty() will still return false because the geometry types list will + /// contain values. + bool is_empty() const; + + /// \brief Returns true if any non-NaN X values were encountered or false otherwise + bool has_x() const; + + /// \brief Returns true if any non-NaN Y values were encountered or false otherwise + bool has_y() const; + + /// \brief Returns true if any non-NaN Z values were encountered or false otherwise + bool has_z() const; + + /// \brief Returns true if any non-NaN M values were encountered or false otherwise + bool has_m() const; + + /// \brief Return the geometry type codes from the well-known binary encountered + /// + /// This implementation always returns sorted output with no duplicates. + std::vector<int32_t> geometry_types() const; Review Comment: Ok, if the vector is short I guess it's not much of a problem. -- This is an automated message from the Apache Git Service. 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