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/**
* Copyright (C) 2022-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/db/record_id.h"
#include "mongo/db/sorter/sorter.h"
#include "mongo/db/storage/column_store.h"
namespace mongo {
/**
* Performs the organizing and sorting steps of a column store index bulk build, presenting an
* interface similar to the 'Sorter' interface. The client can add cells with the 'add()' method
* until none remain and then call 'done()' to get an iterator that returns the cells in sorted
* order.
*
* This class assumes that inputs are _already sorted_ by RecordId. Adding out-of-orders cells will
* result in undefined behavior.
*
* Internally, this class maintains a hash table that maps each path to a sorted list of
* (RecordId, CellValue) pairs. Because we use a hash table and not a sorted data structure (like
* std::map), we need to sort the list of paths when finalizing the output or when writing a spill
* file. The total number of cells inserted into this mapping is potentially very large, making it
* preferable to defer the cost of sorting to the end in order to avoid the cost of a binary tree
* traversal for each inserted cell.
*/
class ColumnStoreSorter {
public:
ColumnStoreSorter(size_t maxMemoryUsageBytes, StringData dbName, SorterFileStats* stats);
void add(PathView path, const RecordId& recordId, CellView cellContents);
size_t numSpills() const {
return _numSpills;
}
struct Key {
PathView path;
RecordId recordId;
struct SorterDeserializeSettings {};
bool operator<(const Key& other) const;
void serializeForSorter(BufBuilder& buf) const;
// Assumes that the source buffer will remain valid for the lifetime of the returned
// ColumnStoreSorter::Key object.
static Key deserializeForSorter(BufReader& buf, SorterDeserializeSettings);
size_t memUsageForSorter() const {
return sizeof(path) + path.size() + recordId.memUsage();
}
Key getOwned() const {
MONGO_UNREACHABLE;
}
};
struct Value {
CellView cell;
struct SorterDeserializeSettings {};
void serializeForSorter(BufBuilder& buf) const;
static Value deserializeForSorter(BufReader& buf, SorterDeserializeSettings);
size_t memUsageForSorter() const {
return sizeof(cell) + cell.size();
}
Value getOwned() const {
MONGO_UNREACHABLE;
}
};
using Iterator = SortIteratorInterface<Key, Value>;
Iterator* done();
private:
class InMemoryIterator;
static SortOptions makeSortOptions(const std::string& dbName, SorterFileStats* stats);
static std::string pathForNewSpillFile();
void spill();
Iterator* inMemoryIterator() const;
const std::string _dbName;
SorterFileStats* _stats; // Unowned
const size_t _maxMemoryUsageBytes;
size_t _memUsed = 0;
size_t _numSpills = 0;
/**
* Mapping from path name to the sorted list of (RecordId, Cell) pairs.
*/
using CellVector = std::vector<std::pair<RecordId, CellValue>>;
StringMap<CellVector> _dataByPath;
std::shared_ptr<Sorter<Key, Value>::File> _spillFile;
std::vector<std::shared_ptr<Iterator>> _spilledFileIterators;
bool _done = false;
};
} // namespace mongo
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