ClickHouse/dbms/src/Interpreters/Aggregator.h
2019-11-11 16:56:11 +08:00

1247 lines
50 KiB
C++

#pragma once
#include <mutex>
#include <memory>
#include <functional>
#include <common/logger_useful.h>
#include <common/StringRef.h>
#include <Common/Arena.h>
#include <Common/HashTable/FixedHashMap.h>
#include <Common/HashTable/HashMap.h>
#include <Common/HashTable/TwoLevelHashMap.h>
#include <Common/HashTable/StringHashMap.h>
#include <Common/HashTable/TwoLevelStringHashMap.h>
#include <Common/ThreadPool.h>
#include <Common/UInt128.h>
#include <Common/LRUCache.h>
#include <Common/ColumnsHashing.h>
#include <Common/assert_cast.h>
#include <Common/filesystemHelpers.h>
#include <DataStreams/IBlockStream_fwd.h>
#include <DataStreams/SizeLimits.h>
#include <Interpreters/AggregateDescription.h>
#include <Interpreters/AggregationCommon.h>
#include <Columns/ColumnString.h>
#include <Columns/ColumnFixedString.h>
#include <Columns/ColumnAggregateFunction.h>
#include <Columns/ColumnVector.h>
#include <Columns/ColumnNullable.h>
#include <Columns/ColumnLowCardinality.h>
namespace DB
{
namespace ErrorCodes
{
extern const int UNKNOWN_AGGREGATED_DATA_VARIANT;
extern const int NOT_ENOUGH_SPACE;
}
class IBlockOutputStream;
/** Different data structures that can be used for aggregation
* For efficiency, the aggregation data itself is put into the pool.
* Data and pool ownership (states of aggregate functions)
* is acquired later - in `convertToBlocks` function, by the ColumnAggregateFunction object.
*
* Most data structures exist in two versions: normal and two-level (TwoLevel).
* A two-level hash table works a little slower with a small number of different keys,
* but with a large number of different keys scales better, because it allows
* parallelize some operations (merging, post-processing) in a natural way.
*
* To ensure efficient work over a wide range of conditions,
* first single-level hash tables are used,
* and when the number of different keys is large enough,
* they are converted to two-level ones.
*
* PS. There are many different approaches to the effective implementation of parallel and distributed aggregation,
* best suited for different cases, and this approach is just one of them, chosen for a combination of reasons.
*/
using AggregatedDataWithoutKey = AggregateDataPtr;
using AggregatedDataWithUInt8Key = FixedHashMap<UInt8, AggregateDataPtr>;
using AggregatedDataWithUInt16Key = FixedHashMap<UInt16, AggregateDataPtr>;
using AggregatedDataWithUInt64Key = HashMap<UInt64, AggregateDataPtr, HashCRC32<UInt64>>;
using AggregatedDataWithShortStringKey = StringHashMap<AggregateDataPtr>;
using AggregatedDataWithStringKey = HashMapWithSavedHash<StringRef, AggregateDataPtr>;
using AggregatedDataWithKeys128 = HashMap<UInt128, AggregateDataPtr, UInt128HashCRC32>;
using AggregatedDataWithKeys256 = HashMap<UInt256, AggregateDataPtr, UInt256HashCRC32>;
using AggregatedDataWithUInt64KeyTwoLevel = TwoLevelHashMap<UInt64, AggregateDataPtr, HashCRC32<UInt64>>;
using AggregatedDataWithShortStringKeyTwoLevel = TwoLevelStringHashMap<AggregateDataPtr>;
using AggregatedDataWithStringKeyTwoLevel = TwoLevelHashMapWithSavedHash<StringRef, AggregateDataPtr>;
using AggregatedDataWithKeys128TwoLevel = TwoLevelHashMap<UInt128, AggregateDataPtr, UInt128HashCRC32>;
using AggregatedDataWithKeys256TwoLevel = TwoLevelHashMap<UInt256, AggregateDataPtr, UInt256HashCRC32>;
/** Variants with better hash function, using more than 32 bits for hash.
* Using for merging phase of external aggregation, where number of keys may be far greater than 4 billion,
* but we keep in memory and merge only sub-partition of them simultaneously.
* TODO We need to switch for better hash function not only for external aggregation,
* but also for huge aggregation results on machines with terabytes of RAM.
*/
using AggregatedDataWithUInt64KeyHash64 = HashMap<UInt64, AggregateDataPtr, DefaultHash<UInt64>>;
using AggregatedDataWithStringKeyHash64 = HashMapWithSavedHash<StringRef, AggregateDataPtr, StringRefHash64>;
using AggregatedDataWithKeys128Hash64 = HashMap<UInt128, AggregateDataPtr, UInt128Hash>;
using AggregatedDataWithKeys256Hash64 = HashMap<UInt256, AggregateDataPtr, UInt256Hash>;
template <typename Base>
struct AggregationDataWithNullKey : public Base
{
using Base::Base;
bool & hasNullKeyData() { return has_null_key_data; }
AggregateDataPtr & getNullKeyData() { return null_key_data; }
bool hasNullKeyData() const { return has_null_key_data; }
const AggregateDataPtr & getNullKeyData() const { return null_key_data; }
size_t size() const { return Base::size() + (has_null_key_data ? 1 : 0); }
bool empty() const { return Base::empty() && !has_null_key_data; }
void clear()
{
Base::clear();
has_null_key_data = false;
}
void clearAndShrink()
{
Base::clearAndShrink();
has_null_key_data = false;
}
private:
bool has_null_key_data = false;
AggregateDataPtr null_key_data = nullptr;
};
template <typename Base>
struct AggregationDataWithNullKeyTwoLevel : public Base
{
using Base::impls;
AggregationDataWithNullKeyTwoLevel() {}
template <typename Other>
explicit AggregationDataWithNullKeyTwoLevel(const Other & other) : Base(other)
{
impls[0].hasNullKeyData() = other.hasNullKeyData();
impls[0].getNullKeyData() = other.getNullKeyData();
}
bool & hasNullKeyData() { return impls[0].hasNullKeyData(); }
AggregateDataPtr & getNullKeyData() { return impls[0].getNullKeyData(); }
bool hasNullKeyData() const { return impls[0].hasNullKeyData(); }
const AggregateDataPtr & getNullKeyData() const { return impls[0].getNullKeyData(); }
};
template <typename ... Types>
using HashTableWithNullKey = AggregationDataWithNullKey<HashMapTable<Types ...>>;
template <typename ... Types>
using StringHashTableWithNullKey = AggregationDataWithNullKey<StringHashMap<Types ...>>;
using AggregatedDataWithNullableUInt8Key = AggregationDataWithNullKey<AggregatedDataWithUInt8Key>;
using AggregatedDataWithNullableUInt16Key = AggregationDataWithNullKey<AggregatedDataWithUInt16Key>;
using AggregatedDataWithNullableUInt64Key = AggregationDataWithNullKey<AggregatedDataWithUInt64Key>;
using AggregatedDataWithNullableStringKey = AggregationDataWithNullKey<AggregatedDataWithStringKey>;
using AggregatedDataWithNullableUInt64KeyTwoLevel = AggregationDataWithNullKeyTwoLevel<
TwoLevelHashMap<UInt64, AggregateDataPtr, HashCRC32<UInt64>,
TwoLevelHashTableGrower<>, HashTableAllocator, HashTableWithNullKey>>;
using AggregatedDataWithNullableShortStringKeyTwoLevel = AggregationDataWithNullKeyTwoLevel<
TwoLevelStringHashMap<AggregateDataPtr, HashTableAllocator, StringHashTableWithNullKey>>;
using AggregatedDataWithNullableStringKeyTwoLevel = AggregationDataWithNullKeyTwoLevel<
TwoLevelHashMapWithSavedHash<StringRef, AggregateDataPtr, DefaultHash<StringRef>,
TwoLevelHashTableGrower<>, HashTableAllocator, HashTableWithNullKey>>;
/// For the case where there is one numeric key.
/// FieldType is UInt8/16/32/64 for any type with corresponding bit width.
template <typename FieldType, typename TData,
bool consecutive_keys_optimization = true>
struct AggregationMethodOneNumber
{
using Data = TData;
using Key = typename Data::key_type;
using Mapped = typename Data::mapped_type;
Data data;
AggregationMethodOneNumber() {}
template <typename Other>
AggregationMethodOneNumber(const Other & other) : data(other.data) {}
/// To use one `Method` in different threads, use different `State`.
using State = ColumnsHashing::HashMethodOneNumber<typename Data::value_type,
Mapped, FieldType, consecutive_keys_optimization>;
/// Use optimization for low cardinality.
static const bool low_cardinality_optimization = false;
// Insert the key from the hash table into columns.
static void insertKeyIntoColumns(const Key & key, MutableColumns & key_columns, const Sizes & /*key_sizes*/)
{
auto key_holder = reinterpret_cast<const char *>(&key);
auto column = static_cast<ColumnVectorHelper *>(key_columns[0].get());
column->insertRawData<sizeof(FieldType)>(key_holder);
}
};
/// For the case where there is one string key.
template <typename TData>
struct AggregationMethodString
{
using Data = TData;
using Key = typename Data::key_type;
using Mapped = typename Data::mapped_type;
Data data;
AggregationMethodString() {}
template <typename Other>
AggregationMethodString(const Other & other) : data(other.data) {}
using State = ColumnsHashing::HashMethodString<typename Data::value_type, Mapped>;
static const bool low_cardinality_optimization = false;
static void insertKeyIntoColumns(const StringRef & key, MutableColumns & key_columns, const Sizes &)
{
key_columns[0]->insertData(key.data, key.size);
}
};
/// Same as above but without cache
template <typename TData>
struct AggregationMethodStringNoCache
{
using Data = TData;
using Key = typename Data::key_type;
using Mapped = typename Data::mapped_type;
Data data;
AggregationMethodStringNoCache() {}
template <typename Other>
AggregationMethodStringNoCache(const Other & other) : data(other.data) {}
using State = ColumnsHashing::HashMethodString<typename Data::value_type, Mapped, true, false>;
static const bool low_cardinality_optimization = false;
static void insertKeyIntoColumns(const StringRef & key, MutableColumns & key_columns, const Sizes &)
{
key_columns[0]->insertData(key.data, key.size);
}
};
/// For the case where there is one fixed-length string key.
template <typename TData>
struct AggregationMethodFixedString
{
using Data = TData;
using Key = typename Data::key_type;
using Mapped = typename Data::mapped_type;
Data data;
AggregationMethodFixedString() {}
template <typename Other>
AggregationMethodFixedString(const Other & other) : data(other.data) {}
using State = ColumnsHashing::HashMethodFixedString<typename Data::value_type, Mapped>;
static const bool low_cardinality_optimization = false;
static void insertKeyIntoColumns(const StringRef & key, MutableColumns & key_columns, const Sizes &)
{
key_columns[0]->insertData(key.data, key.size);
}
};
/// Same as above but without cache
template <typename TData>
struct AggregationMethodFixedStringNoCache
{
using Data = TData;
using Key = typename Data::key_type;
using Mapped = typename Data::mapped_type;
Data data;
AggregationMethodFixedStringNoCache() {}
template <typename Other>
AggregationMethodFixedStringNoCache(const Other & other) : data(other.data) {}
using State = ColumnsHashing::HashMethodFixedString<typename Data::value_type, Mapped, true, false>;
static const bool low_cardinality_optimization = false;
static void insertKeyIntoColumns(const StringRef & key, MutableColumns & key_columns, const Sizes &)
{
key_columns[0]->insertData(key.data, key.size);
}
};
/// Single low cardinality column.
template <typename SingleColumnMethod>
struct AggregationMethodSingleLowCardinalityColumn : public SingleColumnMethod
{
using Base = SingleColumnMethod;
using BaseState = typename Base::State;
using Data = typename Base::Data;
using Key = typename Base::Key;
using Mapped = typename Base::Mapped;
using Base::data;
AggregationMethodSingleLowCardinalityColumn() = default;
template <typename Other>
explicit AggregationMethodSingleLowCardinalityColumn(const Other & other) : Base(other) {}
using State = ColumnsHashing::HashMethodSingleLowCardinalityColumn<BaseState, Mapped, true>;
static const bool low_cardinality_optimization = true;
static void insertKeyIntoColumns(const Key & key,
MutableColumns & key_columns_low_cardinality, const Sizes & /*key_sizes*/)
{
auto col = assert_cast<ColumnLowCardinality *>(key_columns_low_cardinality[0].get());
if constexpr (std::is_same_v<Key, StringRef>)
{
col->insertData(key.data, key.size);
}
else
{
col->insertData(reinterpret_cast<const char *>(&key), sizeof(key));
}
}
};
/// For the case where all keys are of fixed length, and they fit in N (for example, 128) bits.
template <typename TData, bool has_nullable_keys_ = false, bool has_low_cardinality_ = false>
struct AggregationMethodKeysFixed
{
using Data = TData;
using Key = typename Data::key_type;
using Mapped = typename Data::mapped_type;
static constexpr bool has_nullable_keys = has_nullable_keys_;
static constexpr bool has_low_cardinality = has_low_cardinality_;
Data data;
AggregationMethodKeysFixed() {}
template <typename Other>
AggregationMethodKeysFixed(const Other & other) : data(other.data) {}
using State = ColumnsHashing::HashMethodKeysFixed<typename Data::value_type, Key, Mapped, has_nullable_keys, has_low_cardinality>;
static const bool low_cardinality_optimization = false;
static void insertKeyIntoColumns(const Key & key, MutableColumns & key_columns, const Sizes & key_sizes)
{
size_t keys_size = key_columns.size();
static constexpr auto bitmap_size = has_nullable_keys ? std::tuple_size<KeysNullMap<Key>>::value : 0;
/// In any hash key value, column values to be read start just after the bitmap, if it exists.
size_t pos = bitmap_size;
for (size_t i = 0; i < keys_size; ++i)
{
IColumn * observed_column;
ColumnUInt8 * null_map;
bool column_nullable = false;
if constexpr (has_nullable_keys)
column_nullable = isColumnNullable(*key_columns[i]);
/// If we have a nullable column, get its nested column and its null map.
if (column_nullable)
{
ColumnNullable & nullable_col = assert_cast<ColumnNullable &>(*key_columns[i]);
observed_column = &nullable_col.getNestedColumn();
null_map = assert_cast<ColumnUInt8 *>(&nullable_col.getNullMapColumn());
}
else
{
observed_column = key_columns[i].get();
null_map = nullptr;
}
bool is_null = false;
if (column_nullable)
{
/// The current column is nullable. Check if the value of the
/// corresponding key is nullable. Update the null map accordingly.
size_t bucket = i / 8;
size_t offset = i % 8;
UInt8 val = (reinterpret_cast<const UInt8 *>(&key)[bucket] >> offset) & 1;
null_map->insertValue(val);
is_null = val == 1;
}
if (has_nullable_keys && is_null)
observed_column->insertDefault();
else
{
size_t size = key_sizes[i];
observed_column->insertData(reinterpret_cast<const char *>(&key) + pos, size);
pos += size;
}
}
}
};
/** Aggregates by concatenating serialized key values.
* The serialized value differs in that it uniquely allows to deserialize it, having only the position with which it starts.
* That is, for example, for strings, it contains first the serialized length of the string, and then the bytes.
* Therefore, when aggregating by several strings, there is no ambiguity.
*/
template <typename TData>
struct AggregationMethodSerialized
{
using Data = TData;
using Key = typename Data::key_type;
using Mapped = typename Data::mapped_type;
Data data;
AggregationMethodSerialized() {}
template <typename Other>
AggregationMethodSerialized(const Other & other) : data(other.data) {}
using State = ColumnsHashing::HashMethodSerialized<typename Data::value_type, Mapped>;
static const bool low_cardinality_optimization = false;
static void insertKeyIntoColumns(const StringRef & key, MutableColumns & key_columns, const Sizes &)
{
auto pos = key.data;
for (auto & column : key_columns)
pos = column->deserializeAndInsertFromArena(pos);
}
};
class Aggregator;
using ColumnsHashing::HashMethodContext;
using ColumnsHashing::HashMethodContextPtr;
struct AggregatedDataVariants : private boost::noncopyable
{
/** Working with states of aggregate functions in the pool is arranged in the following (inconvenient) way:
* - when aggregating, states are created in the pool using IAggregateFunction::create (inside - `placement new` of arbitrary structure);
* - they must then be destroyed using IAggregateFunction::destroy (inside - calling the destructor of arbitrary structure);
* - if aggregation is complete, then, in the Aggregator::convertToBlocks function, pointers to the states of aggregate functions
* are written to ColumnAggregateFunction; ColumnAggregateFunction "acquires ownership" of them, that is - calls `destroy` in its destructor.
* - if during the aggregation, before call to Aggregator::convertToBlocks, an exception was thrown,
* then the states of aggregate functions must still be destroyed,
* otherwise, for complex states (eg, AggregateFunctionUniq), there will be memory leaks;
* - in this case, to destroy states, the destructor calls Aggregator::destroyAggregateStates method,
* but only if the variable aggregator (see below) is not nullptr;
* - that is, until you transfer ownership of the aggregate function states in the ColumnAggregateFunction, set the variable `aggregator`,
* so that when an exception occurs, the states are correctly destroyed.
*
* PS. This can be corrected by making a pool that knows about which states of aggregate functions and in which order are put in it, and knows how to destroy them.
* But this can hardly be done simply because it is planned to put variable-length strings into the same pool.
* In this case, the pool will not be able to know with what offsets objects are stored.
*/
Aggregator * aggregator = nullptr;
size_t keys_size{}; /// Number of keys. NOTE do we need this field?
Sizes key_sizes; /// Dimensions of keys, if keys of fixed length
/// Pools for states of aggregate functions. Ownership will be later transferred to ColumnAggregateFunction.
Arenas aggregates_pools;
Arena * aggregates_pool{}; /// The pool that is currently used for allocation.
/** Specialization for the case when there are no keys, and for keys not fitted into max_rows_to_group_by.
*/
AggregatedDataWithoutKey without_key = nullptr;
// Disable consecutive key optimization for Uint8/16, because they use a FixedHashMap
// and the lookup there is almost free, so we don't need to cache the last lookup result
std::unique_ptr<AggregationMethodOneNumber<UInt8, AggregatedDataWithUInt8Key, false>> key8;
std::unique_ptr<AggregationMethodOneNumber<UInt16, AggregatedDataWithUInt16Key, false>> key16;
std::unique_ptr<AggregationMethodOneNumber<UInt32, AggregatedDataWithUInt64Key>> key32;
std::unique_ptr<AggregationMethodOneNumber<UInt64, AggregatedDataWithUInt64Key>> key64;
std::unique_ptr<AggregationMethodStringNoCache<AggregatedDataWithShortStringKey>> key_string;
std::unique_ptr<AggregationMethodFixedStringNoCache<AggregatedDataWithShortStringKey>> key_fixed_string;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys128>> keys128;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys256>> keys256;
std::unique_ptr<AggregationMethodSerialized<AggregatedDataWithStringKey>> serialized;
std::unique_ptr<AggregationMethodOneNumber<UInt32, AggregatedDataWithUInt64KeyTwoLevel>> key32_two_level;
std::unique_ptr<AggregationMethodOneNumber<UInt64, AggregatedDataWithUInt64KeyTwoLevel>> key64_two_level;
std::unique_ptr<AggregationMethodStringNoCache<AggregatedDataWithShortStringKeyTwoLevel>> key_string_two_level;
std::unique_ptr<AggregationMethodFixedStringNoCache<AggregatedDataWithShortStringKeyTwoLevel>> key_fixed_string_two_level;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys128TwoLevel>> keys128_two_level;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys256TwoLevel>> keys256_two_level;
std::unique_ptr<AggregationMethodSerialized<AggregatedDataWithStringKeyTwoLevel>> serialized_two_level;
std::unique_ptr<AggregationMethodOneNumber<UInt64, AggregatedDataWithUInt64KeyHash64>> key64_hash64;
std::unique_ptr<AggregationMethodString<AggregatedDataWithStringKeyHash64>> key_string_hash64;
std::unique_ptr<AggregationMethodFixedString<AggregatedDataWithStringKeyHash64>> key_fixed_string_hash64;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys128Hash64>> keys128_hash64;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys256Hash64>> keys256_hash64;
std::unique_ptr<AggregationMethodSerialized<AggregatedDataWithStringKeyHash64>> serialized_hash64;
/// Support for nullable keys.
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys128, true>> nullable_keys128;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys256, true>> nullable_keys256;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys128TwoLevel, true>> nullable_keys128_two_level;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys256TwoLevel, true>> nullable_keys256_two_level;
/// Support for low cardinality.
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodOneNumber<UInt8, AggregatedDataWithNullableUInt8Key, false>>> low_cardinality_key8;
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodOneNumber<UInt16, AggregatedDataWithNullableUInt16Key, false>>> low_cardinality_key16;
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodOneNumber<UInt32, AggregatedDataWithNullableUInt64Key>>> low_cardinality_key32;
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodOneNumber<UInt64, AggregatedDataWithNullableUInt64Key>>> low_cardinality_key64;
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodString<AggregatedDataWithNullableStringKey>>> low_cardinality_key_string;
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodFixedString<AggregatedDataWithNullableStringKey>>> low_cardinality_key_fixed_string;
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodOneNumber<UInt32, AggregatedDataWithNullableUInt64KeyTwoLevel>>> low_cardinality_key32_two_level;
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodOneNumber<UInt64, AggregatedDataWithNullableUInt64KeyTwoLevel>>> low_cardinality_key64_two_level;
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodString<AggregatedDataWithNullableStringKeyTwoLevel>>> low_cardinality_key_string_two_level;
std::unique_ptr<AggregationMethodSingleLowCardinalityColumn<AggregationMethodFixedString<AggregatedDataWithNullableStringKeyTwoLevel>>> low_cardinality_key_fixed_string_two_level;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys128, false, true>> low_cardinality_keys128;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys256, false, true>> low_cardinality_keys256;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys128TwoLevel, false, true>> low_cardinality_keys128_two_level;
std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys256TwoLevel, false, true>> low_cardinality_keys256_two_level;
/// In this and similar macros, the option without_key is not considered.
#define APPLY_FOR_AGGREGATED_VARIANTS(M) \
M(key8, false) \
M(key16, false) \
M(key32, false) \
M(key64, false) \
M(key_string, false) \
M(key_fixed_string, false) \
M(keys128, false) \
M(keys256, false) \
M(serialized, false) \
M(key32_two_level, true) \
M(key64_two_level, true) \
M(key_string_two_level, true) \
M(key_fixed_string_two_level, true) \
M(keys128_two_level, true) \
M(keys256_two_level, true) \
M(serialized_two_level, true) \
M(key64_hash64, false) \
M(key_string_hash64, false) \
M(key_fixed_string_hash64, false) \
M(keys128_hash64, false) \
M(keys256_hash64, false) \
M(serialized_hash64, false) \
M(nullable_keys128, false) \
M(nullable_keys256, false) \
M(nullable_keys128_two_level, true) \
M(nullable_keys256_two_level, true) \
M(low_cardinality_key8, false) \
M(low_cardinality_key16, false) \
M(low_cardinality_key32, false) \
M(low_cardinality_key64, false) \
M(low_cardinality_keys128, false) \
M(low_cardinality_keys256, false) \
M(low_cardinality_key_string, false) \
M(low_cardinality_key_fixed_string, false) \
M(low_cardinality_key32_two_level, true) \
M(low_cardinality_key64_two_level, true) \
M(low_cardinality_keys128_two_level, true) \
M(low_cardinality_keys256_two_level, true) \
M(low_cardinality_key_string_two_level, true) \
M(low_cardinality_key_fixed_string_two_level, true) \
enum class Type
{
EMPTY = 0,
without_key,
#define M(NAME, IS_TWO_LEVEL) NAME,
APPLY_FOR_AGGREGATED_VARIANTS(M)
#undef M
};
Type type = Type::EMPTY;
AggregatedDataVariants() : aggregates_pools(1, std::make_shared<Arena>()), aggregates_pool(aggregates_pools.back().get()) {}
bool empty() const { return type == Type::EMPTY; }
void invalidate() { type = Type::EMPTY; }
~AggregatedDataVariants();
void init(Type type_)
{
switch (type_)
{
case Type::EMPTY: break;
case Type::without_key: break;
#define M(NAME, IS_TWO_LEVEL) \
case Type::NAME: NAME = std::make_unique<decltype(NAME)::element_type>(); break;
APPLY_FOR_AGGREGATED_VARIANTS(M)
#undef M
}
type = type_;
}
/// Number of rows (different keys).
size_t size() const
{
switch (type)
{
case Type::EMPTY: return 0;
case Type::without_key: return 1;
#define M(NAME, IS_TWO_LEVEL) \
case Type::NAME: return NAME->data.size() + (without_key != nullptr);
APPLY_FOR_AGGREGATED_VARIANTS(M)
#undef M
}
__builtin_unreachable();
}
/// The size without taking into account the row in which data is written for the calculation of TOTALS.
size_t sizeWithoutOverflowRow() const
{
switch (type)
{
case Type::EMPTY: return 0;
case Type::without_key: return 1;
#define M(NAME, IS_TWO_LEVEL) \
case Type::NAME: return NAME->data.size();
APPLY_FOR_AGGREGATED_VARIANTS(M)
#undef M
}
__builtin_unreachable();
}
const char * getMethodName() const
{
switch (type)
{
case Type::EMPTY: return "EMPTY";
case Type::without_key: return "without_key";
#define M(NAME, IS_TWO_LEVEL) \
case Type::NAME: return #NAME;
APPLY_FOR_AGGREGATED_VARIANTS(M)
#undef M
}
__builtin_unreachable();
}
bool isTwoLevel() const
{
switch (type)
{
case Type::EMPTY: return false;
case Type::without_key: return false;
#define M(NAME, IS_TWO_LEVEL) \
case Type::NAME: return IS_TWO_LEVEL;
APPLY_FOR_AGGREGATED_VARIANTS(M)
#undef M
}
__builtin_unreachable();
}
#define APPLY_FOR_VARIANTS_CONVERTIBLE_TO_TWO_LEVEL(M) \
M(key32) \
M(key64) \
M(key_string) \
M(key_fixed_string) \
M(keys128) \
M(keys256) \
M(serialized) \
M(nullable_keys128) \
M(nullable_keys256) \
M(low_cardinality_key32) \
M(low_cardinality_key64) \
M(low_cardinality_keys128) \
M(low_cardinality_keys256) \
M(low_cardinality_key_string) \
M(low_cardinality_key_fixed_string) \
#define APPLY_FOR_VARIANTS_NOT_CONVERTIBLE_TO_TWO_LEVEL(M) \
M(key8) \
M(key16) \
M(key64_hash64) \
M(key_string_hash64)\
M(key_fixed_string_hash64) \
M(keys128_hash64) \
M(keys256_hash64) \
M(serialized_hash64) \
M(low_cardinality_key8) \
M(low_cardinality_key16) \
#define APPLY_FOR_VARIANTS_SINGLE_LEVEL(M) \
APPLY_FOR_VARIANTS_NOT_CONVERTIBLE_TO_TWO_LEVEL(M) \
APPLY_FOR_VARIANTS_CONVERTIBLE_TO_TWO_LEVEL(M) \
bool isConvertibleToTwoLevel() const
{
switch (type)
{
#define M(NAME) \
case Type::NAME: return true;
APPLY_FOR_VARIANTS_CONVERTIBLE_TO_TWO_LEVEL(M)
#undef M
default:
return false;
}
}
void convertToTwoLevel();
#define APPLY_FOR_VARIANTS_TWO_LEVEL(M) \
M(key32_two_level) \
M(key64_two_level) \
M(key_string_two_level) \
M(key_fixed_string_two_level) \
M(keys128_two_level) \
M(keys256_two_level) \
M(serialized_two_level) \
M(nullable_keys128_two_level) \
M(nullable_keys256_two_level) \
M(low_cardinality_key32_two_level) \
M(low_cardinality_key64_two_level) \
M(low_cardinality_keys128_two_level) \
M(low_cardinality_keys256_two_level) \
M(low_cardinality_key_string_two_level) \
M(low_cardinality_key_fixed_string_two_level) \
#define APPLY_FOR_LOW_CARDINALITY_VARIANTS(M) \
M(low_cardinality_key8) \
M(low_cardinality_key16) \
M(low_cardinality_key32) \
M(low_cardinality_key64) \
M(low_cardinality_keys128) \
M(low_cardinality_keys256) \
M(low_cardinality_key_string) \
M(low_cardinality_key_fixed_string) \
M(low_cardinality_key32_two_level) \
M(low_cardinality_key64_two_level) \
M(low_cardinality_keys128_two_level) \
M(low_cardinality_keys256_two_level) \
M(low_cardinality_key_string_two_level) \
M(low_cardinality_key_fixed_string_two_level) \
bool isLowCardinality()
{
switch (type)
{
#define M(NAME) \
case Type::NAME: return true;
APPLY_FOR_LOW_CARDINALITY_VARIANTS(M)
#undef M
default:
return false;
}
}
static HashMethodContextPtr createCache(Type type, const HashMethodContext::Settings & settings)
{
switch (type)
{
case Type::without_key: return nullptr;
#define M(NAME, IS_TWO_LEVEL) \
case Type::NAME: \
{ \
using TPtr ## NAME = decltype(AggregatedDataVariants::NAME); \
using T ## NAME = typename TPtr ## NAME ::element_type; \
return T ## NAME ::State::createContext(settings); \
}
APPLY_FOR_AGGREGATED_VARIANTS(M)
#undef M
default:
throw Exception("Unknown aggregated data variant.", ErrorCodes::UNKNOWN_AGGREGATED_DATA_VARIANT);
}
}
};
using AggregatedDataVariantsPtr = std::shared_ptr<AggregatedDataVariants>;
using ManyAggregatedDataVariants = std::vector<AggregatedDataVariantsPtr>;
using ManyAggregatedDataVariantsPtr = std::shared_ptr<ManyAggregatedDataVariants>;
/** How are "total" values calculated with WITH TOTALS?
* (For more details, see TotalsHavingBlockInputStream.)
*
* In the absence of group_by_overflow_mode = 'any', the data is aggregated as usual, but the states of the aggregate functions are not finalized.
* Later, the aggregate function states for all rows (passed through HAVING) are merged into one - this will be TOTALS.
*
* If there is group_by_overflow_mode = 'any', the data is aggregated as usual, except for the keys that did not fit in max_rows_to_group_by.
* For these keys, the data is aggregated into one additional row - see below under the names `overflow_row`, `overflows`...
* Later, the aggregate function states for all rows (passed through HAVING) are merged into one,
* also overflow_row is added or not added (depending on the totals_mode setting) also - this will be TOTALS.
*/
/** Aggregates the source of the blocks.
*/
class Aggregator
{
public:
struct Params
{
/// Data structure of source blocks.
Block src_header;
/// Data structure of intermediate blocks before merge.
Block intermediate_header;
/// What to count.
const ColumnNumbers keys;
const AggregateDescriptions aggregates;
const size_t keys_size;
const size_t aggregates_size;
/// The settings of approximate calculation of GROUP BY.
const bool overflow_row; /// Do we need to put into AggregatedDataVariants::without_key aggregates for keys that are not in max_rows_to_group_by.
const size_t max_rows_to_group_by;
const OverflowMode group_by_overflow_mode;
/// Two-level aggregation settings (used for a large number of keys).
/** With how many keys or the size of the aggregation state in bytes,
* two-level aggregation begins to be used. Enough to reach of at least one of the thresholds.
* 0 - the corresponding threshold is not specified.
*/
const size_t group_by_two_level_threshold;
const size_t group_by_two_level_threshold_bytes;
/// Settings to flush temporary data to the filesystem (external aggregation).
const size_t max_bytes_before_external_group_by; /// 0 - do not use external aggregation.
/// Return empty result when aggregating without keys on empty set.
bool empty_result_for_aggregation_by_empty_set;
const std::string tmp_path;
/// Settings is used to determine cache size. No threads are created.
size_t max_threads;
const size_t min_free_disk_space;
Params(
const Block & src_header_,
const ColumnNumbers & keys_, const AggregateDescriptions & aggregates_,
bool overflow_row_, size_t max_rows_to_group_by_, OverflowMode group_by_overflow_mode_,
size_t group_by_two_level_threshold_, size_t group_by_two_level_threshold_bytes_,
size_t max_bytes_before_external_group_by_,
bool empty_result_for_aggregation_by_empty_set_,
const std::string & tmp_path_, size_t max_threads_,
size_t min_free_disk_space_)
: src_header(src_header_),
keys(keys_), aggregates(aggregates_), keys_size(keys.size()), aggregates_size(aggregates.size()),
overflow_row(overflow_row_), max_rows_to_group_by(max_rows_to_group_by_), group_by_overflow_mode(group_by_overflow_mode_),
group_by_two_level_threshold(group_by_two_level_threshold_), group_by_two_level_threshold_bytes(group_by_two_level_threshold_bytes_),
max_bytes_before_external_group_by(max_bytes_before_external_group_by_),
empty_result_for_aggregation_by_empty_set(empty_result_for_aggregation_by_empty_set_),
tmp_path(tmp_path_), max_threads(max_threads_),
min_free_disk_space(min_free_disk_space_)
{
}
/// Only parameters that matter during merge.
Params(const Block & intermediate_header_,
const ColumnNumbers & keys_, const AggregateDescriptions & aggregates_, bool overflow_row_, size_t max_threads_)
: Params(Block(), keys_, aggregates_, overflow_row_, 0, OverflowMode::THROW, 0, 0, 0, false, "", max_threads_, 0)
{
intermediate_header = intermediate_header_;
}
};
Aggregator(const Params & params_);
/// Aggregate the source. Get the result in the form of one of the data structures.
void execute(const BlockInputStreamPtr & stream, AggregatedDataVariants & result);
using AggregateColumns = std::vector<ColumnRawPtrs>;
using AggregateColumnsData = std::vector<ColumnAggregateFunction::Container *>;
using AggregateColumnsConstData = std::vector<const ColumnAggregateFunction::Container *>;
using AggregateFunctionsPlainPtrs = std::vector<IAggregateFunction *>;
/// Process one block. Return false if the processing should be aborted (with group_by_overflow_mode = 'break').
bool executeOnBlock(const Block & block, AggregatedDataVariants & result,
ColumnRawPtrs & key_columns, AggregateColumns & aggregate_columns, /// Passed to not create them anew for each block
bool & no_more_keys);
bool executeOnBlock(Columns columns, UInt64 num_rows, AggregatedDataVariants & result,
ColumnRawPtrs & key_columns, AggregateColumns & aggregate_columns, /// Passed to not create them anew for each block
bool & no_more_keys);
/** Convert the aggregation data structure into a block.
* If overflow_row = true, then aggregates for rows that are not included in max_rows_to_group_by are put in the first block.
*
* If final = false, then ColumnAggregateFunction is created as the aggregation columns with the state of the calculations,
* which can then be combined with other states (for distributed query processing).
* If final = true, then columns with ready values are created as aggregate columns.
*/
BlocksList convertToBlocks(AggregatedDataVariants & data_variants, bool final, size_t max_threads) const;
/** Merge several aggregation data structures and output the result as a block stream.
*/
std::unique_ptr<IBlockInputStream> mergeAndConvertToBlocks(ManyAggregatedDataVariants & data_variants, bool final, size_t max_threads) const;
ManyAggregatedDataVariants prepareVariantsToMerge(ManyAggregatedDataVariants & data_variants) const;
/** Merge the stream of partially aggregated blocks into one data structure.
* (Pre-aggregate several blocks that represent the result of independent aggregations from remote servers.)
*/
void mergeStream(const BlockInputStreamPtr & stream, AggregatedDataVariants & result, size_t max_threads);
using BucketToBlocks = std::map<Int32, BlocksList>;
/// Merge partially aggregated blocks separated to buckets into one data structure.
void mergeBlocks(BucketToBlocks bucket_to_blocks, AggregatedDataVariants & result, size_t max_threads);
/// Merge several partially aggregated blocks into one.
/// Precondition: for all blocks block.info.is_overflows flag must be the same.
/// (either all blocks are from overflow data or none blocks are).
/// The resulting block has the same value of is_overflows flag.
Block mergeBlocks(BlocksList & blocks, bool final);
/** Split block with partially-aggregated data to many blocks, as if two-level method of aggregation was used.
* This is needed to simplify merging of that data with other results, that are already two-level.
*/
std::vector<Block> convertBlockToTwoLevel(const Block & block);
using CancellationHook = std::function<bool()>;
/** Set a function that checks whether the current task can be aborted.
*/
void setCancellationHook(const CancellationHook cancellation_hook);
/// For external aggregation.
void writeToTemporaryFile(AggregatedDataVariants & data_variants);
bool hasTemporaryFiles() const { return !temporary_files.empty(); }
struct TemporaryFiles
{
std::vector<std::unique_ptr<Poco::TemporaryFile>> files;
size_t sum_size_uncompressed = 0;
size_t sum_size_compressed = 0;
mutable std::mutex mutex;
bool empty() const
{
std::lock_guard lock(mutex);
return files.empty();
}
};
const TemporaryFiles & getTemporaryFiles() const { return temporary_files; }
/// Get data structure of the result.
Block getHeader(bool final) const;
protected:
friend struct AggregatedDataVariants;
friend class MergingAndConvertingBlockInputStream;
friend class ConvertingAggregatedToChunksTransform;
friend class ConvertingAggregatedToChunksSource;
Params params;
AggregatedDataVariants::Type method_chosen;
Sizes key_sizes;
HashMethodContextPtr aggregation_state_cache;
AggregateFunctionsPlainPtrs aggregate_functions;
/** This array serves two purposes.
*
* 1. Function arguments are collected side by side, and they do not need to be collected from different places. Also the array is made zero-terminated.
* The inner loop (for the case without_key) is almost twice as compact; performance gain of about 30%.
*
* 2. Calling a function by pointer is better than a virtual call, because in the case of a virtual call,
* GCC 5.1.2 generates code that, at each iteration of the loop, reloads the function address from memory into the register
* (the offset value in the virtual function table).
*/
struct AggregateFunctionInstruction
{
const IAggregateFunction * that;
IAggregateFunction::AddFunc func;
size_t state_offset;
const IColumn ** arguments;
const IAggregateFunction * batch_that;
const IColumn ** batch_arguments;
const UInt64 * offsets = nullptr;
};
using AggregateFunctionInstructions = std::vector<AggregateFunctionInstruction>;
Sizes offsets_of_aggregate_states; /// The offset to the n-th aggregate function in a row of aggregate functions.
size_t total_size_of_aggregate_states = 0; /// The total size of the row from the aggregate functions.
// add info to track alignment requirement
// If there are states whose alignmentment are v1, ..vn, align_aggregate_states will be max(v1, ... vn)
size_t align_aggregate_states = 1;
bool all_aggregates_has_trivial_destructor = false;
/// How many RAM were used to process the query before processing the first block.
Int64 memory_usage_before_aggregation = 0;
std::mutex mutex;
Logger * log = &Logger::get("Aggregator");
/// Returns true if you can abort the current task.
CancellationHook isCancelled;
/// For external aggregation.
TemporaryFiles temporary_files;
/** Select the aggregation method based on the number and types of keys. */
AggregatedDataVariants::Type chooseAggregationMethod();
/** Create states of aggregate functions for one key.
*/
void createAggregateStates(AggregateDataPtr & aggregate_data) const;
/** Call `destroy` methods for states of aggregate functions.
* Used in the exception handler for aggregation, since RAII in this case is not applicable.
*/
void destroyAllAggregateStates(AggregatedDataVariants & result);
/// Process one data block, aggregate the data into a hash table.
template <typename Method>
void executeImpl(
Method & method,
Arena * aggregates_pool,
size_t rows,
ColumnRawPtrs & key_columns,
AggregateFunctionInstruction * aggregate_instructions,
bool no_more_keys,
AggregateDataPtr overflow_row) const;
/// Specialization for a particular value no_more_keys.
template <bool no_more_keys, typename Method>
void executeImplCase(
Method & method,
typename Method::State & state,
Arena * aggregates_pool,
size_t rows,
AggregateFunctionInstruction * aggregate_instructions,
AggregateDataPtr overflow_row) const;
template <typename Method>
void executeImplBatch(
Method & method,
typename Method::State & state,
Arena * aggregates_pool,
size_t rows,
AggregateFunctionInstruction * aggregate_instructions) const;
/// For case when there are no keys (all aggregate into one row).
void executeWithoutKeyImpl(
AggregatedDataWithoutKey & res,
size_t rows,
AggregateFunctionInstruction * aggregate_instructions,
Arena * arena) const;
template <typename Method>
void writeToTemporaryFileImpl(
AggregatedDataVariants & data_variants,
Method & method,
IBlockOutputStream & out);
protected:
/// Merge NULL key data from hash table `src` into `dst`.
template <typename Method, typename Table>
void mergeDataNullKey(
Table & table_dst,
Table & table_src,
Arena * arena) const;
/// Merge data from hash table `src` into `dst`.
template <typename Method, typename Table>
void mergeDataImpl(
Table & table_dst,
Table & table_src,
Arena * arena) const;
/// Merge data from hash table `src` into `dst`, but only for keys that already exist in dst. In other cases, merge the data into `overflows`.
template <typename Method, typename Table>
void mergeDataNoMoreKeysImpl(
Table & table_dst,
AggregatedDataWithoutKey & overflows,
Table & table_src,
Arena * arena) const;
/// Same, but ignores the rest of the keys.
template <typename Method, typename Table>
void mergeDataOnlyExistingKeysImpl(
Table & table_dst,
Table & table_src,
Arena * arena) const;
void mergeWithoutKeyDataImpl(
ManyAggregatedDataVariants & non_empty_data) const;
template <typename Method>
void mergeSingleLevelDataImpl(
ManyAggregatedDataVariants & non_empty_data) const;
template <typename Method, typename Table>
void convertToBlockImpl(
Method & method,
Table & data,
MutableColumns & key_columns,
AggregateColumnsData & aggregate_columns,
MutableColumns & final_aggregate_columns,
bool final) const;
template <typename Method, typename Table>
void convertToBlockImplFinal(
Method & method,
Table & data,
MutableColumns & key_columns,
MutableColumns & final_aggregate_columns) const;
template <typename Method, typename Table>
void convertToBlockImplNotFinal(
Method & method,
Table & data,
MutableColumns & key_columns,
AggregateColumnsData & aggregate_columns) const;
template <typename Filler>
Block prepareBlockAndFill(
AggregatedDataVariants & data_variants,
bool final,
size_t rows,
Filler && filler) const;
template <typename Method>
Block convertOneBucketToBlock(
AggregatedDataVariants & data_variants,
Method & method,
bool final,
size_t bucket) const;
Block mergeAndConvertOneBucketToBlock(
ManyAggregatedDataVariants & variants,
Arena * arena,
bool final,
size_t bucket) const;
Block prepareBlockAndFillWithoutKey(AggregatedDataVariants & data_variants, bool final, bool is_overflows) const;
Block prepareBlockAndFillSingleLevel(AggregatedDataVariants & data_variants, bool final) const;
BlocksList prepareBlocksAndFillTwoLevel(AggregatedDataVariants & data_variants, bool final, ThreadPool * thread_pool) const;
template <typename Method>
BlocksList prepareBlocksAndFillTwoLevelImpl(
AggregatedDataVariants & data_variants,
Method & method,
bool final,
ThreadPool * thread_pool) const;
template <bool no_more_keys, typename Method, typename Table>
void mergeStreamsImplCase(
Block & block,
Arena * aggregates_pool,
Method & method,
Table & data,
AggregateDataPtr overflow_row) const;
template <typename Method, typename Table>
void mergeStreamsImpl(
Block & block,
Arena * aggregates_pool,
Method & method,
Table & data,
AggregateDataPtr overflow_row,
bool no_more_keys) const;
void mergeWithoutKeyStreamsImpl(
Block & block,
AggregatedDataVariants & result) const;
template <typename Method>
void mergeBucketImpl(
ManyAggregatedDataVariants & data, Int32 bucket, Arena * arena) const;
template <typename Method>
void convertBlockToTwoLevelImpl(
Method & method,
Arena * pool,
ColumnRawPtrs & key_columns,
const Block & source,
std::vector<Block> & destinations) const;
template <typename Method, typename Table>
void destroyImpl(Table & table) const;
void destroyWithoutKey(
AggregatedDataVariants & result) const;
/** Checks constraints on the maximum number of keys for aggregation.
* If it is exceeded, then, depending on the group_by_overflow_mode, either
* - throws an exception;
* - returns false, which means that execution must be aborted;
* - sets the variable no_more_keys to true.
*/
bool checkLimits(size_t result_size, bool & no_more_keys) const;
};
/** Get the aggregation variant by its type. */
template <typename Method> Method & getDataVariant(AggregatedDataVariants & variants);
#define M(NAME, IS_TWO_LEVEL) \
template <> inline decltype(AggregatedDataVariants::NAME)::element_type & getDataVariant<decltype(AggregatedDataVariants::NAME)::element_type>(AggregatedDataVariants & variants) { return *variants.NAME; }
APPLY_FOR_AGGREGATED_VARIANTS(M)
#undef M
}