ClickHouse/dbms/include/DB/Columns/ColumnConst.h

210 lines
6.6 KiB
C++

#pragma once
#include <Poco/SharedPtr.h>
#include <DB/Core/Field.h>
#include <DB/Core/Exception.h>
#include <DB/Core/ErrorCodes.h>
#include <DB/Columns/ColumnVector.h>
#include <DB/Columns/IColumn.h>
#include <DB/DataTypes/IDataType.h>
namespace DB
{
using Poco::SharedPtr;
class IColumnConst : public IColumn
{
public:
bool isConst() const { return true; }
virtual ColumnPtr convertToFullColumn() const = 0;
};
/** шаблон для столбцов-констант (столбцов одинаковых значений).
*/
template <typename T>
class ColumnConst : public IColumnConst
{
public:
typedef T Type;
typedef typename NearestFieldType<T>::Type FieldType;
/// Для ColumnConst<Array> data_type_ должен быть ненулевым.
/// Для ColumnConst<String> data_type_ должен быть ненулевым, если тип данных FixedString.
ColumnConst(size_t s_, const T & data_, DataTypePtr data_type_ = DataTypePtr()) : s(s_), data(data_), data_type(data_type_) {}
std::string getName() const { return "ColumnConst<" + TypeName<T>::get() + ">"; }
bool isNumeric() const { return IsNumber<T>::value; }
bool isFixed() const { return IsNumber<T>::value; }
size_t sizeOfField() const { return sizeof(T); }
ColumnPtr cloneResized(size_t s_) const { return new ColumnConst(s_, data); }
size_t size() const { return s; }
Field operator[](size_t n) const { return FieldType(data); }
void get(size_t n, Field & res) const { res = FieldType(data); }
ColumnPtr cut(size_t start, size_t length) const
{
return new ColumnConst<T>(length, data, data_type);
}
void insert(const Field & x)
{
if (x.get<FieldType>() != FieldType(data))
throw Exception("Cannot insert different element into constant column " + getName(),
ErrorCodes::CANNOT_INSERT_ELEMENT_INTO_CONSTANT_COLUMN);
++s;
}
void insertData(const char * pos, size_t length)
{
throw Exception("Cannot insert element into constant column " + getName(), ErrorCodes::NOT_IMPLEMENTED);
}
void insertFrom(const IColumn & src, size_t n)
{
if (data != static_cast<const ColumnConst<T> &>(src).data)
throw Exception("Cannot insert different element into constant column " + getName(),
ErrorCodes::CANNOT_INSERT_ELEMENT_INTO_CONSTANT_COLUMN);
++s;
}
void insertDefault() { ++s; }
ColumnPtr filter(const Filter & filt) const
{
if (s != filt.size())
throw Exception("Size of filter doesn't match size of column.", ErrorCodes::SIZES_OF_COLUMNS_DOESNT_MATCH);
size_t new_size = 0;
for (Filter::const_iterator it = filt.begin(); it != filt.end(); ++it)
if (*it)
++new_size;
return new ColumnConst<T>(new_size, data, data_type);
}
ColumnPtr replicate(const Offsets_t & offsets) const
{
if (s != offsets.size())
throw Exception("Size of offsets doesn't match size of column.", ErrorCodes::SIZES_OF_COLUMNS_DOESNT_MATCH);
return new ColumnConst<T>(offsets.back(), data, data_type);
}
size_t byteSize() const { return sizeof(data) + sizeof(s); }
ColumnPtr permute(const Permutation & perm, size_t limit) const
{
if (limit == 0)
limit = s;
else
limit = std::min(s, limit);
if (perm.size() < limit)
throw Exception("Size of permutation is less than required.", ErrorCodes::SIZES_OF_COLUMNS_DOESNT_MATCH);
return new ColumnConst<T>(limit, data, data_type);
}
int compareAt(size_t n, size_t m, const IColumn & rhs_, int nan_direction_hint) const
{
const ColumnConst<T> & rhs = static_cast<const ColumnConst<T> &>(rhs_);
return data < rhs.data /// TODO: правильное сравнение NaN-ов в константных столбцах.
? -1
: (data == rhs.data
? 0
: 1);
}
void getPermutation(bool reverse, size_t limit, Permutation & res) const
{
res.resize(s);
for (size_t i = 0; i < s; ++i)
res[i] = i;
}
StringRef getDataAt(size_t n) const;
StringRef getDataAtWithTerminatingZero(size_t n) const;
/** Более эффективные методы манипуляции */
T & getData() { return data; }
const T & getData() const { return data; }
/** Преобразование из константы в полноценный столбец */
ColumnPtr convertToFullColumn() const;
void getExtremes(Field & min, Field & max) const
{
min = FieldType(data);
max = FieldType(data);
}
private:
size_t s;
T data;
DataTypePtr data_type;
};
typedef ColumnConst<String> ColumnConstString;
typedef ColumnConst<Array> ColumnConstArray;
template <typename T> ColumnPtr ColumnConst<T>::convertToFullColumn() const
{
ColumnVector<T> * res = new ColumnVector<T>;
res->getData().assign(s, data);
return res;
}
template <> ColumnPtr ColumnConst<String>::convertToFullColumn() const;
template <> ColumnPtr ColumnConst<Array>::convertToFullColumn() const;
template <typename T> StringRef ColumnConst<T>::getDataAt(size_t n) const
{
throw Exception("Method getDataAt is not supported for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
}
template <> inline StringRef ColumnConst<String>::getDataAt(size_t n) const
{
return StringRef(data);
}
/// Для элементарных типов.
template <typename T> StringRef getDataAtImpl(size_t n, const T & data)
{
return StringRef(reinterpret_cast<const char *>(&data), sizeof(data));
}
template <> inline StringRef ColumnConst<UInt8 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <> inline StringRef ColumnConst<UInt16 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <> inline StringRef ColumnConst<UInt32 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <> inline StringRef ColumnConst<UInt64 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <> inline StringRef ColumnConst<Int8 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <> inline StringRef ColumnConst<Int16 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <> inline StringRef ColumnConst<Int32 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <> inline StringRef ColumnConst<Int64 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <> inline StringRef ColumnConst<Float32 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <> inline StringRef ColumnConst<Float64 >::getDataAt(size_t n) const { return getDataAtImpl(n, data); }
template <typename T> StringRef ColumnConst<T>::getDataAtWithTerminatingZero(size_t n) const
{
return getDataAt(n);
}
template <> inline StringRef ColumnConst<String>::getDataAtWithTerminatingZero(size_t n) const
{
return StringRef(data.data(), data.size() + 1);
}
}