mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-04 21:42:39 +00:00
129 lines
3.2 KiB
C++
129 lines
3.2 KiB
C++
|
//
|
||
|
|
// HashStatistic.h
|
||
|
|
//
|
||
|
|
// $Id: //poco/1.4/Foundation/include/Poco/HashStatistic.h#1 $
|
||
|
|
//
|
||
|
|
// Library: Foundation
|
||
|
|
// Package: Hashing
|
||
|
|
// Module: HashStatistic
|
||
|
|
//
|
||
|
|
// Definition of the HashStatistic class.
|
||
|
|
//
|
||
|
|
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
|
||
|
|
// and Contributors.
|
||
|
|
//
|
||
|
|
// SPDX-License-Identifier: BSL-1.0
|
||
|
|
//
|
||
|
|
|
||
|
|
|
||
|
|
#ifndef Foundation_HashStatistic_INCLUDED
|
||
|
|
#define Foundation_HashStatistic_INCLUDED
|
||
|
|
|
||
|
|
|
||
|
|
#include "Poco/Foundation.h"
|
||
|
|
#include <vector>
|
||
|
|
|
||
|
|
|
||
|
|
namespace Poco {
|
||
|
|
|
||
|
|
|
||
|
|
//@ deprecated
|
||
|
|
class Foundation_API HashStatistic
|
||
|
|
/// HashStatistic class bundles statistical information on the current state of a HashTable
|
||
|
|
{
|
||
|
|
public:
|
||
|
|
HashStatistic(
|
||
|
|
UInt32 tableSize,
|
||
|
|
UInt32 numEntries,
|
||
|
|
UInt32 numZeroEntries,
|
||
|
|
UInt32 maxEntry,
|
||
|
|
std::vector<UInt32> details = std::vector<UInt32>());
|
||
|
|
/// Creates the HashStatistic.
|
||
|
|
|
||
|
|
virtual ~HashStatistic();
|
||
|
|
/// Destroys the HashStatistic.
|
||
|
|
|
||
|
|
UInt32 maxPositionsOfTable() const;
|
||
|
|
/// Returns the maximum number of different hash values possible for the table
|
||
|
|
|
||
|
|
UInt32 numberOfEntries() const;
|
||
|
|
/// Returns the total number of entries currently stored in the HashTable
|
||
|
|
|
||
|
|
UInt32 numberOfZeroPositions() const;
|
||
|
|
/// Returns the number of hash positions that contain no entry.
|
||
|
|
|
||
|
|
double avgEntriesPerHash() const;
|
||
|
|
/// Returns the average number of entries per position in the Hashtable, the higher this value the less efficient
|
||
|
|
/// performs hashing. If a large value is returned and getNumberOfZeroPositions also returns a large value, this
|
||
|
|
/// indicates an inefficient hashing function. If the number of zero entries is low, resizing the HashTable, should
|
||
|
|
/// be enough to improve performance
|
||
|
|
|
||
|
|
double avgEntriesPerHashExclZeroEntries() const;
|
||
|
|
/// Same as getAvgEntriesPerHash but hash values that contain no entry are ignored,
|
||
|
|
/// getAvgEntriesPerHashExclZeroEntries >= getAvgEntriesPerHash will always be true.
|
||
|
|
|
||
|
|
UInt32 maxEntriesPerHash() const;
|
||
|
|
/// Returns the maximum number of entries per hash value found in the current table.
|
||
|
|
|
||
|
|
const std::vector<UInt32> detailedEntriesPerHash() const;
|
||
|
|
/// Will either be an empty vector or will contain for each possible hash value, the number of entries currently stored
|
||
|
|
|
||
|
|
std::string toString() const;
|
||
|
|
/// Converts the whole data structure into a string.
|
||
|
|
|
||
|
|
private:
|
||
|
|
UInt32 _sizeOfTable;
|
||
|
|
UInt32 _numberOfEntries;
|
||
|
|
UInt32 _numZeroEntries;
|
||
|
|
UInt32 _maxEntriesPerHash;
|
||
|
|
std::vector<UInt32> _detailedEntriesPerHash;
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
inline UInt32 HashStatistic::maxPositionsOfTable() const
|
||
|
|
{
|
||
|
|
return _sizeOfTable;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
inline UInt32 HashStatistic::numberOfEntries() const
|
||
|
|
{
|
||
|
|
return _numberOfEntries;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
inline UInt32 HashStatistic::numberOfZeroPositions() const
|
||
|
|
{
|
||
|
|
return _numZeroEntries;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
inline double HashStatistic::avgEntriesPerHash() const
|
||
|
|
{
|
||
|
|
return ((double) numberOfEntries()) / maxPositionsOfTable();
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
inline double HashStatistic::avgEntriesPerHashExclZeroEntries() const
|
||
|
|
{
|
||
|
|
return ((double) numberOfEntries()) / (maxPositionsOfTable() - numberOfZeroPositions());
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
inline UInt32 HashStatistic::maxEntriesPerHash() const
|
||
|
|
{
|
||
|
|
return _maxEntriesPerHash;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
inline const std::vector<UInt32> HashStatistic::detailedEntriesPerHash() const
|
||
|
|
{
|
||
|
|
return _detailedEntriesPerHash;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
} // namespace Poco
|
||
|
|
|
||
|
|
|
||
|
|
#endif // Foundation_HashStatistic_INCLUDED
|