HappenLee commented on a change in pull request #7793: URL: https://github.com/apache/incubator-doris/pull/7793#discussion_r792626573
########## File path: be/src/vec/aggregate_functions/aggregate_function_topn.h ########## @@ -0,0 +1,272 @@ +// 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 <parallel_hashmap/phmap.h> +#include <rapidjson/stringbuffer.h> +#include <rapidjson/writer.h> + +#include <unordered_map> + +#include "vec/aggregate_functions/aggregate_function.h" +#include "vec/aggregate_functions/aggregate_function_simple_factory.h" +#include "vec/aggregate_functions/helpers.h" +#include "vec/data_types/data_type_date_time.h" +#include "vec/data_types/data_type_decimal.h" +#include "vec/data_types/data_type_number.h" +#include "vec/data_types/data_type_string.h" +#include "vec/io/io_helper.h" + +namespace doris::vectorized { + +// space-saving algorithm +struct AggregateFunctionTopNData { + void set_paramenters(int input_top_num, int space_expand_rate = 50) { + top_num = input_top_num; + capacity = (uint64_t)top_num * space_expand_rate; + } + + void add(const std::string& value) { + auto it = counter_map.find(value); + if (it != counter_map.end()) { + it->second++; + } else { + counter_map.insert({value, 1}); + } + } + + void merge(const AggregateFunctionTopNData& rhs) { + top_num = rhs.top_num; + capacity = rhs.capacity; + + bool lhs_full = (counter_map.size() >= capacity); + bool rhs_full = (rhs.counter_map.size() >= capacity); + + uint64_t lhs_min = 0; + uint64_t rhs_min = 0; + + if (lhs_full) { + lhs_min = UINT64_MAX; + for (auto it : counter_map) { + lhs_min = std::min(lhs_min, it.second); + } + } + + if (rhs_full) { + rhs_min = UINT64_MAX; + for (auto it : rhs.counter_map) { + rhs_min = std::min(rhs_min, it.second); + } + + for (auto& it : counter_map) { + it.second += rhs_min; + } + } + + for (auto rhs_it : rhs.counter_map) { + auto lhs_it = counter_map.find(rhs_it.first); + if (lhs_it != counter_map.end()) { + lhs_it->second += rhs_it.second - rhs_min; + } else { + counter_map.insert({rhs_it.first, rhs_it.second + lhs_min}); + } + } + } + + std::vector<std::pair<uint64_t, std::string>> get_remain_vector() const { + std::vector<std::pair<uint64_t, std::string>> counter_vector; + for (auto it : counter_map) { + counter_vector.emplace_back(it.second, it.first); + } + std::sort(counter_vector.begin(), counter_vector.end(), + std::greater<std::pair<uint64_t, std::string>>()); + return counter_vector; + } + + void write(BufferWritable& buf) const { + write_binary(top_num, buf); + write_binary(capacity, buf); + + uint64_t element_number = std::min(capacity, (uint64_t)counter_map.size()); + write_binary(element_number, buf); + + auto counter_vector = get_remain_vector(); + + for (auto i = 0; i < element_number; i++) { + auto element = counter_vector[i]; + write_binary(element.second, buf); + write_binary(element.first, buf); + } + } + + void read(BufferReadable& buf) { + read_binary(top_num, buf); + read_binary(capacity, buf); + + uint64_t element_number = 0; + read_binary(element_number, buf); + + counter_map.clear(); + std::pair<std::string, uint64_t> element; + for (auto i = 0; i < element_number; i++) { + read_binary(element.first, buf); + read_binary(element.second, buf); + counter_map.insert(element); + } + } + + std::string get() const { + auto counter_vector = get_remain_vector(); + + rapidjson::StringBuffer buffer; + rapidjson::Writer<rapidjson::StringBuffer> writer(buffer); + + writer.StartObject(); + for (int i = 0; i < std::min((int)counter_vector.size(), top_num); i++) { + const auto& element = counter_vector[i]; + writer.Key(element.second.c_str()); + writer.Uint64(element.first); + } + writer.EndObject(); + + return buffer.GetString(); + } + + void reset() { counter_map.clear(); } + + int top_num; + uint64_t capacity; + phmap::flat_hash_map<std::string, uint64_t> counter_map; +}; + +// specific to_string() +template <typename T> +struct NumricDataImplTopN { Review comment: Use FE to cast argment to string/varchar, remove the unless code -- 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] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
