ClickHouse/dbms/include/DB/Interpreters/AggregationCommon.h
2017-01-17 18:03:32 +00:00

402 lines
11 KiB
C++

#pragma once
#include <array>
#include <DB/Common/SipHash.h>
#include <DB/Common/Arena.h>
#include <DB/Common/UInt128.h>
#include <DB/Core/Defines.h>
#include <DB/Core/StringRef.h>
#include <DB/Columns/IColumn.h>
#include <DB/Columns/ColumnsNumber.h>
#include <DB/Columns/ColumnFixedString.h>
#include <DB/Columns/ColumnNullable.h>
template <>
struct DefaultHash<StringRef> : public StringRefHash {};
namespace DB
{
using Sizes = std::vector<size_t>;
/// When packing the values of nullable columns at a given row, we have to
/// store the fact that these values are nullable or not. This is achieved
/// by encoding this information as a bitmap. Let S be the size in bytes of
/// a packed values binary blob and T the number of bytes we may place into
/// this blob, the size that the bitmap shall occupy in the blob is equal to:
/// ceil(T/8). Thus we must have: S = T + ceil(T/8). Below we indicate for
/// each value of S, the corresponding value of T, and the bitmap size:
///
/// 32,28,4
/// 16,14,2
/// 8,7,1
/// 4,3,1
/// 2,1,1
///
namespace
{
template <typename T>
constexpr auto getBitmapSize()
{
return
(sizeof(T) == 32) ?
4 :
(sizeof(T) == 16) ?
2 :
((sizeof(T) == 8) ?
1 :
((sizeof(T) == 4) ?
1 :
((sizeof(T) == 2) ?
1 :
0)));
}
}
template <typename T>
using KeysNullMap = std::array<UInt8, getBitmapSize<T>()>;
/// Pack into a binary blob of type T a set of fixed-size keys. Granted that all the keys fit into the
/// binary blob, they are disposed in it consecutively.
template <typename T>
static inline T ALWAYS_INLINE packFixed(
size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, const Sizes & key_sizes)
{
union
{
T key;
char bytes[sizeof(key)] = {};
};
size_t offset = 0;
for (size_t j = 0; j < keys_size; ++j)
{
switch (key_sizes[j])
{
case 1:
memcpy(bytes + offset, &static_cast<const ColumnUInt8 *>(key_columns[j])->getData()[i], 1);
offset += 1;
break;
case 2:
memcpy(bytes + offset, &static_cast<const ColumnUInt16 *>(key_columns[j])->getData()[i], 2);
offset += 2;
break;
case 4:
memcpy(bytes + offset, &static_cast<const ColumnUInt32 *>(key_columns[j])->getData()[i], 4);
offset += 4;
break;
case 8:
memcpy(bytes + offset, &static_cast<const ColumnUInt64 *>(key_columns[j])->getData()[i], 8);
offset += 8;
break;
default:
memcpy(bytes + offset, &static_cast<const ColumnFixedString *>(key_columns[j])->getChars()[i * key_sizes[j]], key_sizes[j]);
offset += key_sizes[j];
}
}
return key;
}
/// Similar as above but supports nullable values.
template <typename T>
static inline T ALWAYS_INLINE packFixed(
size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, const Sizes & key_sizes,
const KeysNullMap<T> & bitmap)
{
union
{
T key;
char bytes[sizeof(key)] = {};
};
size_t offset = 0;
static constexpr auto bitmap_size = std::tuple_size<KeysNullMap<T>>::value;
static constexpr bool has_bitmap = bitmap_size > 0;
if (has_bitmap)
{
memcpy(bytes + offset, bitmap.data(), bitmap_size * sizeof(UInt8));
offset += bitmap_size;
}
for (size_t j = 0; j < keys_size; ++j)
{
bool is_null;
if (!has_bitmap)
is_null = false;
else
{
size_t bucket = j / 8;
size_t off = j % 8;
is_null = ((bitmap[bucket] >> off) & 1) == 1;
}
if (is_null)
continue;
switch (key_sizes[j])
{
case 1:
memcpy(bytes + offset, &static_cast<const ColumnUInt8 *>(key_columns[j])->getData()[i], 1);
offset += 1;
break;
case 2:
memcpy(bytes + offset, &static_cast<const ColumnUInt16 *>(key_columns[j])->getData()[i], 2);
offset += 2;
break;
case 4:
memcpy(bytes + offset, &static_cast<const ColumnUInt32 *>(key_columns[j])->getData()[i], 4);
offset += 4;
break;
case 8:
memcpy(bytes + offset, &static_cast<const ColumnUInt64 *>(key_columns[j])->getData()[i], 8);
offset += 8;
break;
default:
memcpy(bytes + offset, &static_cast<const ColumnFixedString *>(key_columns[j])->getChars()[i * key_sizes[j]], key_sizes[j]);
offset += key_sizes[j];
}
}
return key;
}
/// Hash a set of keys into a UInt128 value.
static inline UInt128 ALWAYS_INLINE hash128(
size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, StringRefs & keys)
{
UInt128 key;
SipHash hash;
for (size_t j = 0; j < keys_size; ++j)
{
/// Хэшируем ключ.
keys[j] = key_columns[j]->getDataAtWithTerminatingZero(i);
hash.update(keys[j].data, keys[j].size);
}
hash.get128(key.first, key.second);
return key;
}
/// Almost the same as above but it doesn't return any reference to key data.
static inline UInt128 ALWAYS_INLINE hash128(
size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns)
{
UInt128 key;
SipHash hash;
for (size_t j = 0; j < keys_size; ++j)
key_columns[j]->updateHashWithValue(i, hash);
hash.get128(key.first, key.second);
return key;
}
/// Скопировать ключи в пул. Потом разместить в пуле StringRef-ы на них и вернуть указатель на первый.
static inline StringRef * ALWAYS_INLINE placeKeysInPool(
size_t i, size_t keys_size, StringRefs & keys, Arena & pool)
{
for (size_t j = 0; j < keys_size; ++j)
{
char * place = pool.alloc(keys[j].size);
memcpy(place, keys[j].data, keys[j].size); /// TODO padding в Arena и memcpySmall
keys[j].data = place;
}
/// Размещаем в пуле StringRef-ы на только что скопированные ключи.
char * res = pool.alloc(keys_size * sizeof(StringRef));
memcpy(res, &keys[0], keys_size * sizeof(StringRef));
return reinterpret_cast<StringRef *>(res);
}
/// Скопировать ключи в пул. Потом разместить в пуле StringRef-ы на них и вернуть указатель на первый.
static inline StringRef * ALWAYS_INLINE extractKeysAndPlaceInPool(
size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, StringRefs & keys, Arena & pool)
{
for (size_t j = 0; j < keys_size; ++j)
{
keys[j] = key_columns[j]->getDataAtWithTerminatingZero(i);
char * place = pool.alloc(keys[j].size);
memcpy(place, keys[j].data, keys[j].size);
keys[j].data = place;
}
/// Размещаем в пуле StringRef-ы на только что скопированные ключи.
char * res = pool.alloc(keys_size * sizeof(StringRef));
memcpy(res, &keys[0], keys_size * sizeof(StringRef));
return reinterpret_cast<StringRef *>(res);
}
/// Place the specified keys into a continuous memory chunk. The implementation
/// of this function depends on whether some keys are nullable or not. See comments
/// below for the specialized implementations.
template <bool has_nullable_keys>
static StringRef extractKeysAndPlaceInPoolContiguous(
size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, StringRefs & keys, Arena & pool);
/// Implementation for the case when there are no nullable keys.
/// Copy the specified keys to a continuous memory chunk of a pool.
/// Subsequently append StringRef objects referring to each key.
///
/// [key1][key2]...[keyN][ref1][ref2]...[refN]
/// ^ ^ : | |
/// +-----|--------:-----+ |
/// : +--------:-----------+
/// : :
/// <-------------->
/// (1)
///
/// Return a StringRef object, referring to the area (1) of the memory
/// chunk that contains the keys. In other words, we ignore their StringRefs.
template <>
inline StringRef ALWAYS_INLINE extractKeysAndPlaceInPoolContiguous<false>(
size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, StringRefs & keys, Arena & pool)
{
size_t sum_keys_size = 0;
for (size_t j = 0; j < keys_size; ++j)
{
keys[j] = key_columns[j]->getDataAtWithTerminatingZero(i);
sum_keys_size += keys[j].size;
}
char * res = pool.alloc(sum_keys_size + keys_size * sizeof(StringRef));
char * place = res;
for (size_t j = 0; j < keys_size; ++j)
{
memcpy(place, keys[j].data, keys[j].size);
keys[j].data = place;
place += keys[j].size;
}
/// Размещаем в пуле StringRef-ы на только что скопированные ключи.
memcpy(place, &keys[0], keys_size * sizeof(StringRef));
return {res, sum_keys_size};
}
/// Implementation for the case where there is at least one nullable key.
/// Inside a continuous memory chunk of a pool, put a bitmap that indicates
/// for each specified key whether its value is null or not. Copy the keys
/// whose values are not nulls to the memory chunk. Subsequently append
/// StringRef objects referring to each key, even those who contain a null.
///
/// [bitmap][key1][key2][key4]...[keyN][ref1][ref2][ref3 (null)]...[refN]
/// : ^ ^ : | |
/// : +-----|--------------:-----+ |
/// : +--------------:-----------+
/// : :
/// <---------------------------->
/// (1)
///
/// Return a StringRef object, referring to the area (1) of the memory
/// chunk that contains the bitmap and the keys. In other words, we ignore
/// the keys' StringRefs.
template <>
inline StringRef ALWAYS_INLINE extractKeysAndPlaceInPoolContiguous<true>(
size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, StringRefs & keys, Arena & pool)
{
size_t bitmap_size = keys_size / 8;
if ((keys_size % 8) != 0) { ++bitmap_size; }
std::vector<UInt8> bitmap(bitmap_size);
/// Prepare the keys to be stored. Create the bitmap.
size_t keys_bytes = 0;
for (size_t j = 0; j < keys_size; ++j)
{
const IColumn * observed_column;
bool is_null;
if (key_columns[j]->isNullable())
{
const ColumnNullable & nullable_col = static_cast<const ColumnNullable &>(*key_columns[j]);
observed_column = nullable_col.getNestedColumn().get();
const auto & null_map = nullable_col.getNullMap();
is_null = null_map[i] == 1;
}
else
{
observed_column = key_columns[j];
is_null = false;
}
if (is_null)
{
size_t bucket = j / 8;
size_t offset = j % 8;
bitmap[bucket] |= UInt8(1) << offset;
keys[j] = StringRef{};
}
else
{
keys[j] = observed_column->getDataAtWithTerminatingZero(i);
keys_bytes += keys[j].size;
}
}
/// Allocate space for bitmap + non-null keys + StringRef objects.
char * res = pool.alloc(bitmap_size + keys_bytes + keys_size * sizeof(StringRef));
char * place = res;
/// Store the bitmap.
memcpy(place, bitmap.data(), bitmap.size());
place += bitmap.size();
/// Store the non-null keys data.
for (size_t j = 0; j < keys_size; ++j)
{
size_t bucket = j / 8;
size_t offset = j % 8;
if (((bitmap[bucket] >> offset) & 1) == 0)
{
memcpy(place, keys[j].data, keys[j].size);
keys[j].data = place;
place += keys[j].size;
}
}
/// Store StringRef objects for all the keys, i.e. even for those
/// whose value is null.
memcpy(place, &keys[0], keys_size * sizeof(StringRef));
return {res, bitmap_size + keys_bytes};
}
/** Сериализовать ключи в непрерывный кусок памяти.
*/
static inline StringRef ALWAYS_INLINE serializeKeysToPoolContiguous(
size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, StringRefs & keys, Arena & pool)
{
const char * begin = nullptr;
size_t sum_size = 0;
for (size_t j = 0; j < keys_size; ++j)
sum_size += key_columns[j]->serializeValueIntoArena(i, pool, begin).size;
return {begin, sum_size};
}
}