wgtmac commented on code in PR #43273: URL: https://github.com/apache/arrow/pull/43273#discussion_r1705201001
########## cpp/src/arrow/array/statistics.h: ########## @@ -0,0 +1,75 @@ +// 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 <cstdint> +#include <optional> +#include <string> +#include <string_view> +#include <variant> + +#include "arrow/util/visibility.h" + +namespace arrow { + +/// \brief Statistics for an Array +/// +/// Apache Arrow format doesn't have statistics but data source such +/// as Apache Parquet may have statistics. Statistics associated with +/// data source can be read unified API via this class. +struct ARROW_EXPORT ArrayStatistics { + using ValueType = + std::variant<bool, int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, int64_t, + uint64_t, std::string, std::string_view>; + + ArrayStatistics() = default; + ~ArrayStatistics() = default; + + /// \brief The number of null values, may not be set + std::optional<int64_t> null_count = std::nullopt; + + /// \brief The number of distinct values, may not be set + std::optional<int64_t> distinct_count = std::nullopt; + + /// \brief The minimum value, may not be set + std::optional<ValueType> min = std::nullopt; + + /// \brief Whether the minimum value is exact or not, may not be set + std::optional<bool> is_min_exact = std::nullopt; Review Comment: > Well, if it's unknown, then it's not exact. The third state is not useful IMHO. I agree with @pitrou. We can simply mark it as not exact if this field is missing. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
