ClickHouse/dbms/Dictionaries/FlatDictionary.cpp

#include "FlatDictionary.h"
#include <IO/WriteHelpers.h>
#include "DictionaryBlockInputStream.h"
#include "DictionaryFactory.h"

namespace DB
{
namespace ErrorCodes
{
    extern const int TYPE_MISMATCH;
    extern const int ARGUMENT_OUT_OF_BOUND;
    extern const int BAD_ARGUMENTS;
    extern const int DICTIONARY_IS_EMPTY;
    extern const int UNSUPPORTED_METHOD;
}

static const auto initial_array_size = 1024;
static const auto max_array_size = 500000;


FlatDictionary::FlatDictionary(
    const std::string & database_,
    const std::string & name_,
    const DictionaryStructure & dict_struct_,
    DictionarySourcePtr source_ptr_,
    const DictionaryLifetime dict_lifetime_,
    bool require_nonempty_,
    BlockPtr saved_block_)
    : database(database_)
    , name(name_)
    , full_name{database_.empty() ? name_ : (database_ + "." + name_)}
    , dict_struct(dict_struct_)
    , source_ptr{std::move(source_ptr_)}
    , dict_lifetime(dict_lifetime_)
    , require_nonempty(require_nonempty_)
    , loaded_ids(initial_array_size, false)
    , saved_block{std::move(saved_block_)}
{
    createAttributes();
    loadData();
    calculateBytesAllocated();
}


void FlatDictionary::toParent(const PaddedPODArray<Key> & ids, PaddedPODArray<Key> & out) const
{
    const auto null_value = std::get<UInt64>(hierarchical_attribute->null_values);

    getItemsImpl<UInt64, UInt64>(
        *hierarchical_attribute,
        ids,
        [&](const size_t row, const UInt64 value) { out[row] = value; },
        [&](const size_t) { return null_value; });
}


/// Allow to use single value in same way as array.
static inline FlatDictionary::Key getAt(const PaddedPODArray<FlatDictionary::Key> & arr, const size_t idx)
{
    return arr[idx];
}
static inline FlatDictionary::Key getAt(const FlatDictionary::Key & value, const size_t)
{
    return value;
}

template <typename ChildType, typename AncestorType>
void FlatDictionary::isInImpl(const ChildType & child_ids, const AncestorType & ancestor_ids, PaddedPODArray<UInt8> & out) const
{
    const auto null_value = std::get<UInt64>(hierarchical_attribute->null_values);
    const auto & attr = std::get<ContainerType<Key>>(hierarchical_attribute->arrays);
    const auto rows = out.size();

    size_t loaded_size = attr.size();
    for (const auto row : ext::range(0, rows))
    {
        auto id = getAt(child_ids, row);
        const auto ancestor_id = getAt(ancestor_ids, row);

        while (id < loaded_size && id != null_value && id != ancestor_id)
            id = attr[id];

        out[row] = id != null_value && id == ancestor_id;
    }

    query_count.fetch_add(rows, std::memory_order_relaxed);
}


void FlatDictionary::isInVectorVector(
    const PaddedPODArray<Key> & child_ids, const PaddedPODArray<Key> & ancestor_ids, PaddedPODArray<UInt8> & out) const
{
    isInImpl(child_ids, ancestor_ids, out);
}

void FlatDictionary::isInVectorConstant(const PaddedPODArray<Key> & child_ids, const Key ancestor_id, PaddedPODArray<UInt8> & out) const
{
    isInImpl(child_ids, ancestor_id, out);
}

void FlatDictionary::isInConstantVector(const Key child_id, const PaddedPODArray<Key> & ancestor_ids, PaddedPODArray<UInt8> & out) const
{
    isInImpl(child_id, ancestor_ids, out);
}


#define DECLARE(TYPE) \
    void FlatDictionary::get##TYPE(const std::string & attribute_name, const PaddedPODArray<Key> & ids, ResultArrayType<TYPE> & out) const \
    { \
        const auto & attribute = getAttribute(attribute_name); \
        checkAttributeType(full_name, attribute_name, attribute.type, AttributeUnderlyingType::ut##TYPE); \
\
        const auto null_value = std::get<TYPE>(attribute.null_values); \
\
        getItemsImpl<TYPE, TYPE>( \
            attribute, ids, [&](const size_t row, const auto value) { out[row] = value; }, [&](const size_t) { return null_value; }); \
    }
DECLARE(UInt8)
DECLARE(UInt16)
DECLARE(UInt32)
DECLARE(UInt64)
DECLARE(UInt128)
DECLARE(Int8)
DECLARE(Int16)
DECLARE(Int32)
DECLARE(Int64)
DECLARE(Float32)
DECLARE(Float64)
DECLARE(Decimal32)
DECLARE(Decimal64)
DECLARE(Decimal128)
#undef DECLARE

void FlatDictionary::getString(const std::string & attribute_name, const PaddedPODArray<Key> & ids, ColumnString * out) const
{
    const auto & attribute = getAttribute(attribute_name);
    checkAttributeType(full_name, attribute_name, attribute.type, AttributeUnderlyingType::utString);

    const auto & null_value = std::get<StringRef>(attribute.null_values);

    getItemsImpl<StringRef, StringRef>(
        attribute,
        ids,
        [&](const size_t, const StringRef value) { out->insertData(value.data, value.size); },
        [&](const size_t) { return null_value; });
}

#define DECLARE(TYPE) \
    void FlatDictionary::get##TYPE( \
        const std::string & attribute_name, \
        const PaddedPODArray<Key> & ids, \
        const PaddedPODArray<TYPE> & def, \
        ResultArrayType<TYPE> & out) const \
    { \
        const auto & attribute = getAttribute(attribute_name); \
        checkAttributeType(full_name, attribute_name, attribute.type, AttributeUnderlyingType::ut##TYPE); \
\
        getItemsImpl<TYPE, TYPE>( \
            attribute, ids, [&](const size_t row, const auto value) { out[row] = value; }, [&](const size_t row) { return def[row]; }); \
    }
DECLARE(UInt8)
DECLARE(UInt16)
DECLARE(UInt32)
DECLARE(UInt64)
DECLARE(UInt128)
DECLARE(Int8)
DECLARE(Int16)
DECLARE(Int32)
DECLARE(Int64)
DECLARE(Float32)
DECLARE(Float64)
DECLARE(Decimal32)
DECLARE(Decimal64)
DECLARE(Decimal128)
#undef DECLARE

void FlatDictionary::getString(
    const std::string & attribute_name, const PaddedPODArray<Key> & ids, const ColumnString * const def, ColumnString * const out) const
{
    const auto & attribute = getAttribute(attribute_name);
    checkAttributeType(full_name, attribute_name, attribute.type, AttributeUnderlyingType::utString);

    getItemsImpl<StringRef, StringRef>(
        attribute,
        ids,
        [&](const size_t, const StringRef value) { out->insertData(value.data, value.size); },
        [&](const size_t row) { return def->getDataAt(row); });
}

#define DECLARE(TYPE) \
    void FlatDictionary::get##TYPE( \
        const std::string & attribute_name, const PaddedPODArray<Key> & ids, const TYPE def, ResultArrayType<TYPE> & out) const \
    { \
        const auto & attribute = getAttribute(attribute_name); \
        checkAttributeType(full_name, attribute_name, attribute.type, AttributeUnderlyingType::ut##TYPE); \
\
        getItemsImpl<TYPE, TYPE>( \
            attribute, ids, [&](const size_t row, const auto value) { out[row] = value; }, [&](const size_t) { return def; }); \
    }
DECLARE(UInt8)
DECLARE(UInt16)
DECLARE(UInt32)
DECLARE(UInt64)
DECLARE(UInt128)
DECLARE(Int8)
DECLARE(Int16)
DECLARE(Int32)
DECLARE(Int64)
DECLARE(Float32)
DECLARE(Float64)
DECLARE(Decimal32)
DECLARE(Decimal64)
DECLARE(Decimal128)
#undef DECLARE

void FlatDictionary::getString(
    const std::string & attribute_name, const PaddedPODArray<Key> & ids, const String & def, ColumnString * const out) const
{
    const auto & attribute = getAttribute(attribute_name);
    checkAttributeType(full_name, attribute_name, attribute.type, AttributeUnderlyingType::utString);

    FlatDictionary::getItemsImpl<StringRef, StringRef>(
        attribute,
        ids,
        [&](const size_t, const StringRef value) { out->insertData(value.data, value.size); },
        [&](const size_t) { return StringRef{def}; });
}


void FlatDictionary::has(const PaddedPODArray<Key> & ids, PaddedPODArray<UInt8> & out) const
{
    const auto & attribute = attributes.front();

    switch (attribute.type)
    {
        case AttributeUnderlyingType::utUInt8:
            has<UInt8>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utUInt16:
            has<UInt16>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utUInt32:
            has<UInt32>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utUInt64:
            has<UInt64>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utUInt128:
            has<UInt128>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utInt8:
            has<Int8>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utInt16:
            has<Int16>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utInt32:
            has<Int32>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utInt64:
            has<Int64>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utFloat32:
            has<Float32>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utFloat64:
            has<Float64>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utString:
            has<String>(attribute, ids, out);
            break;

        case AttributeUnderlyingType::utDecimal32:
            has<Decimal32>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utDecimal64:
            has<Decimal64>(attribute, ids, out);
            break;
        case AttributeUnderlyingType::utDecimal128:
            has<Decimal128>(attribute, ids, out);
            break;
    }
}


void FlatDictionary::createAttributes()
{
    const auto size = dict_struct.attributes.size();
    attributes.reserve(size);

    for (const auto & attribute : dict_struct.attributes)
    {
        attribute_index_by_name.emplace(attribute.name, attributes.size());
        attributes.push_back(createAttributeWithType(attribute.underlying_type, attribute.null_value));

        if (attribute.hierarchical)
        {
            hierarchical_attribute = &attributes.back();

            if (hierarchical_attribute->type != AttributeUnderlyingType::utUInt64)
                throw Exception{full_name + ": hierarchical attribute must be UInt64.", ErrorCodes::TYPE_MISMATCH};
        }
    }
}

void FlatDictionary::blockToAttributes(const Block & block)
{
    const IColumn & id_column = *block.safeGetByPosition(0).column;
    element_count += id_column.size();

    for (const size_t attribute_idx : ext::range(0, attributes.size()))
    {
        const IColumn & attribute_column = *block.safeGetByPosition(attribute_idx + 1).column;
        Attribute & attribute = attributes[attribute_idx];

        for (const auto row_idx : ext::range(0, id_column.size()))
            setAttributeValue(attribute, id_column[row_idx].get<UInt64>(), attribute_column[row_idx]);
    }
}

void FlatDictionary::updateData()
{
    if (!saved_block || saved_block->rows() == 0)
    {
        auto stream = source_ptr->loadUpdatedAll();
        stream->readPrefix();

        while (const auto block = stream->read())
        {
            /// We are using this to keep saved data if input stream consists of multiple blocks
            if (!saved_block)
                saved_block = std::make_shared<DB::Block>(block.cloneEmpty());
            for (const auto attribute_idx : ext::range(0, attributes.size() + 1))
            {
                const IColumn & update_column = *block.getByPosition(attribute_idx).column.get();
                MutableColumnPtr saved_column = saved_block->getByPosition(attribute_idx).column->assumeMutable();
                saved_column->insertRangeFrom(update_column, 0, update_column.size());
            }
        }
        stream->readSuffix();
    }
    else
    {
        auto stream = source_ptr->loadUpdatedAll();
        stream->readPrefix();

        while (Block block = stream->read())
        {
            const auto & saved_id_column = *saved_block->safeGetByPosition(0).column;
            const auto & update_id_column = *block.safeGetByPosition(0).column;

            std::unordered_map<Key, std::vector<size_t>> update_ids;
            for (size_t row = 0; row < update_id_column.size(); ++row)
            {
                const auto id = update_id_column.get64(row);
                update_ids[id].push_back(row);
            }

            const size_t saved_rows = saved_id_column.size();
            IColumn::Filter filter(saved_rows);
            std::unordered_map<Key, std::vector<size_t>>::iterator it;

            for (size_t row = 0; row < saved_id_column.size(); ++row)
            {
                auto id = saved_id_column.get64(row);
                it = update_ids.find(id);

                if (it != update_ids.end())
                    filter[row] = 0;
                else
                    filter[row] = 1;
            }

            auto block_columns = block.mutateColumns();
            for (const auto attribute_idx : ext::range(0, attributes.size() + 1))
            {
                auto & column = saved_block->safeGetByPosition(attribute_idx).column;
                const auto & filtered_column = column->filter(filter, -1);

                block_columns[attribute_idx]->insertRangeFrom(*filtered_column.get(), 0, filtered_column->size());
            }

            saved_block->setColumns(std::move(block_columns));
        }
        stream->readSuffix();
    }

    if (saved_block)
        blockToAttributes(*saved_block.get());
}

void FlatDictionary::loadData()
{
    if (!source_ptr->hasUpdateField())
    {
        auto stream = source_ptr->loadAll();
        stream->readPrefix();

        while (const auto block = stream->read())
            blockToAttributes(block);

        stream->readSuffix();
    }
    else
        updateData();

    if (require_nonempty && 0 == element_count)
        throw Exception{full_name + ": dictionary source is empty and 'require_nonempty' property is set.", ErrorCodes::DICTIONARY_IS_EMPTY};
}


template <typename T>
void FlatDictionary::addAttributeSize(const Attribute & attribute)
{
    const auto & array_ref = std::get<ContainerType<T>>(attribute.arrays);
    bytes_allocated += sizeof(PaddedPODArray<T>) + array_ref.allocated_bytes();
    bucket_count = array_ref.capacity();
}


void FlatDictionary::calculateBytesAllocated()
{
    bytes_allocated += attributes.size() * sizeof(attributes.front());

    for (const auto & attribute : attributes)
    {
        switch (attribute.type)
        {
            case AttributeUnderlyingType::utUInt8:
                addAttributeSize<UInt8>(attribute);
                break;
            case AttributeUnderlyingType::utUInt16:
                addAttributeSize<UInt16>(attribute);
                break;
            case AttributeUnderlyingType::utUInt32:
                addAttributeSize<UInt32>(attribute);
                break;
            case AttributeUnderlyingType::utUInt64:
                addAttributeSize<UInt64>(attribute);
                break;
            case AttributeUnderlyingType::utUInt128:
                addAttributeSize<UInt128>(attribute);
                break;
            case AttributeUnderlyingType::utInt8:
                addAttributeSize<Int8>(attribute);
                break;
            case AttributeUnderlyingType::utInt16:
                addAttributeSize<Int16>(attribute);
                break;
            case AttributeUnderlyingType::utInt32:
                addAttributeSize<Int32>(attribute);
                break;
            case AttributeUnderlyingType::utInt64:
                addAttributeSize<Int64>(attribute);
                break;
            case AttributeUnderlyingType::utFloat32:
                addAttributeSize<Float32>(attribute);
                break;
            case AttributeUnderlyingType::utFloat64:
                addAttributeSize<Float64>(attribute);
                break;

            case AttributeUnderlyingType::utDecimal32:
                addAttributeSize<Decimal32>(attribute);
                break;
            case AttributeUnderlyingType::utDecimal64:
                addAttributeSize<Decimal64>(attribute);
                break;
            case AttributeUnderlyingType::utDecimal128:
                addAttributeSize<Decimal128>(attribute);
                break;

            case AttributeUnderlyingType::utString:
            {
                addAttributeSize<StringRef>(attribute);
                bytes_allocated += sizeof(Arena) + attribute.string_arena->size();

                break;
            }
        }
    }
}


template <typename T>
void FlatDictionary::createAttributeImpl(Attribute & attribute, const Field & null_value)
{
    attribute.null_values = T(null_value.get<NearestFieldType<T>>());
    const auto & null_value_ref = std::get<T>(attribute.null_values);
    attribute.arrays.emplace<ContainerType<T>>(initial_array_size, null_value_ref);
}

template <>
void FlatDictionary::createAttributeImpl<String>(Attribute & attribute, const Field & null_value)
{
    attribute.string_arena = std::make_unique<Arena>();
    const String & string = null_value.get<String>();
    const char * string_in_arena = attribute.string_arena->insert(string.data(), string.size());
    attribute.null_values.emplace<StringRef>(string_in_arena, string.size());
    attribute.arrays.emplace<ContainerType<StringRef>>(initial_array_size, StringRef(string_in_arena, string.size()));
}


FlatDictionary::Attribute FlatDictionary::createAttributeWithType(const AttributeUnderlyingType type, const Field & null_value)
{
    Attribute attr{type, {}, {}, {}};

    switch (type)
    {
        case AttributeUnderlyingType::utUInt8:
            createAttributeImpl<UInt8>(attr, null_value);
            break;
        case AttributeUnderlyingType::utUInt16:
            createAttributeImpl<UInt16>(attr, null_value);
            break;
        case AttributeUnderlyingType::utUInt32:
            createAttributeImpl<UInt32>(attr, null_value);
            break;
        case AttributeUnderlyingType::utUInt64:
            createAttributeImpl<UInt64>(attr, null_value);
            break;
        case AttributeUnderlyingType::utUInt128:
            createAttributeImpl<UInt128>(attr, null_value);
            break;
        case AttributeUnderlyingType::utInt8:
            createAttributeImpl<Int8>(attr, null_value);
            break;
        case AttributeUnderlyingType::utInt16:
            createAttributeImpl<Int16>(attr, null_value);
            break;
        case AttributeUnderlyingType::utInt32:
            createAttributeImpl<Int32>(attr, null_value);
            break;
        case AttributeUnderlyingType::utInt64:
            createAttributeImpl<Int64>(attr, null_value);
            break;
        case AttributeUnderlyingType::utFloat32:
            createAttributeImpl<Float32>(attr, null_value);
            break;
        case AttributeUnderlyingType::utFloat64:
            createAttributeImpl<Float64>(attr, null_value);
            break;
        case AttributeUnderlyingType::utString:
            createAttributeImpl<String>(attr, null_value);
            break;

        case AttributeUnderlyingType::utDecimal32:
            createAttributeImpl<Decimal32>(attr, null_value);
            break;
        case AttributeUnderlyingType::utDecimal64:
            createAttributeImpl<Decimal64>(attr, null_value);
            break;
        case AttributeUnderlyingType::utDecimal128:
            createAttributeImpl<Decimal128>(attr, null_value);
            break;
    }

    return attr;
}


template <typename AttributeType, typename OutputType, typename ValueSetter, typename DefaultGetter>
void FlatDictionary::getItemsImpl(
    const Attribute & attribute, const PaddedPODArray<Key> & ids, ValueSetter && set_value, DefaultGetter && get_default) const
{
    const auto & attr = std::get<ContainerType<AttributeType>>(attribute.arrays);
    const auto rows = ext::size(ids);

    for (const auto row : ext::range(0, rows))
    {
        const auto id = ids[row];
        set_value(row, id < ext::size(attr) && loaded_ids[id] ? static_cast<OutputType>(attr[id]) : get_default(row));
    }

    query_count.fetch_add(rows, std::memory_order_relaxed);
}

template <typename T>
void FlatDictionary::resize(Attribute & attribute, const Key id)
{
    if (id >= max_array_size)
        throw Exception{full_name + ": identifier should be less than " + toString(max_array_size), ErrorCodes::ARGUMENT_OUT_OF_BOUND};

    auto & array = std::get<ContainerType<T>>(attribute.arrays);
    if (id >= array.size())
    {
        const size_t elements_count = id + 1; //id=0 -> elements_count=1
        loaded_ids.resize(elements_count, false);
        array.resize_fill(elements_count, std::get<T>(attribute.null_values));
    }
}

template <typename T>
void FlatDictionary::setAttributeValueImpl(Attribute & attribute, const Key id, const T & value)
{
    resize<T>(attribute, id);
    auto & array = std::get<ContainerType<T>>(attribute.arrays);
    array[id] = value;
    loaded_ids[id] = true;
}

template <>
void FlatDictionary::setAttributeValueImpl<String>(Attribute & attribute, const Key id, const String & value)
{
    resize<StringRef>(attribute, id);
    const auto string_in_arena = attribute.string_arena->insert(value.data(), value.size());
    auto & array = std::get<ContainerType<StringRef>>(attribute.arrays);
    array[id] = StringRef{string_in_arena, value.size()};
    loaded_ids[id] = true;
}

void FlatDictionary::setAttributeValue(Attribute & attribute, const Key id, const Field & value)
{
    switch (attribute.type)
    {
        case AttributeUnderlyingType::utUInt8:
            setAttributeValueImpl<UInt8>(attribute, id, value.get<UInt64>());
            break;
        case AttributeUnderlyingType::utUInt16:
            setAttributeValueImpl<UInt16>(attribute, id, value.get<UInt64>());
            break;
        case AttributeUnderlyingType::utUInt32:
            setAttributeValueImpl<UInt32>(attribute, id, value.get<UInt64>());
            break;
        case AttributeUnderlyingType::utUInt64:
            setAttributeValueImpl<UInt64>(attribute, id, value.get<UInt64>());
            break;
        case AttributeUnderlyingType::utUInt128:
            setAttributeValueImpl<UInt128>(attribute, id, value.get<UInt128>());
            break;
        case AttributeUnderlyingType::utInt8:
            setAttributeValueImpl<Int8>(attribute, id, value.get<Int64>());
            break;
        case AttributeUnderlyingType::utInt16:
            setAttributeValueImpl<Int16>(attribute, id, value.get<Int64>());
            break;
        case AttributeUnderlyingType::utInt32:
            setAttributeValueImpl<Int32>(attribute, id, value.get<Int64>());
            break;
        case AttributeUnderlyingType::utInt64:
            setAttributeValueImpl<Int64>(attribute, id, value.get<Int64>());
            break;
        case AttributeUnderlyingType::utFloat32:
            setAttributeValueImpl<Float32>(attribute, id, value.get<Float64>());
            break;
        case AttributeUnderlyingType::utFloat64:
            setAttributeValueImpl<Float64>(attribute, id, value.get<Float64>());
            break;
        case AttributeUnderlyingType::utString:
            setAttributeValueImpl<String>(attribute, id, value.get<String>());
            break;

        case AttributeUnderlyingType::utDecimal32:
            setAttributeValueImpl<Decimal32>(attribute, id, value.get<Decimal32>());
            break;
        case AttributeUnderlyingType::utDecimal64:
            setAttributeValueImpl<Decimal64>(attribute, id, value.get<Decimal64>());
            break;
        case AttributeUnderlyingType::utDecimal128:
            setAttributeValueImpl<Decimal128>(attribute, id, value.get<Decimal128>());
            break;
    }
}


const FlatDictionary::Attribute & FlatDictionary::getAttribute(const std::string & attribute_name) const
{
    const auto it = attribute_index_by_name.find(attribute_name);
    if (it == std::end(attribute_index_by_name))
        throw Exception{full_name + ": no such attribute '" + attribute_name + "'", ErrorCodes::BAD_ARGUMENTS};

    return attributes[it->second];
}


template <typename T>
void FlatDictionary::has(const Attribute &, const PaddedPODArray<Key> & ids, PaddedPODArray<UInt8> & out) const
{
    const auto ids_count = ext::size(ids);

    for (const auto i : ext::range(0, ids_count))
    {
        const auto id = ids[i];
        out[i] = id < loaded_ids.size() && loaded_ids[id];
    }

    query_count.fetch_add(ids_count, std::memory_order_relaxed);
}


PaddedPODArray<FlatDictionary::Key> FlatDictionary::getIds() const
{
    const auto ids_count = ext::size(loaded_ids);

    PaddedPODArray<Key> ids;
    for (auto idx : ext::range(0, ids_count))
        if (loaded_ids[idx])
            ids.push_back(idx);
    return ids;
}

BlockInputStreamPtr FlatDictionary::getBlockInputStream(const Names & column_names, size_t max_block_size) const
{
    using BlockInputStreamType = DictionaryBlockInputStream<FlatDictionary, Key>;
    return std::make_shared<BlockInputStreamType>(shared_from_this(), max_block_size, getIds(), column_names);
}

void registerDictionaryFlat(DictionaryFactory & factory)
{
    auto create_layout = [=](const std::string & full_name,
                             const DictionaryStructure & dict_struct,
                             const Poco::Util::AbstractConfiguration & config,
                             const std::string & config_prefix,
                             DictionarySourcePtr source_ptr) -> DictionaryPtr
    {
        if (dict_struct.key)
            throw Exception{"'key' is not supported for dictionary of layout 'flat'", ErrorCodes::UNSUPPORTED_METHOD};

        if (dict_struct.range_min || dict_struct.range_max)
            throw Exception{full_name
                                + ": elements .structure.range_min and .structure.range_max should be defined only "
                                  "for a dictionary of layout 'range_hashed'",
                            ErrorCodes::BAD_ARGUMENTS};

        const String database = config.getString(config_prefix + ".database", "");
        const String name = config.getString(config_prefix + ".name");
        const DictionaryLifetime dict_lifetime{config, config_prefix + ".lifetime"};
        const bool require_nonempty = config.getBool(config_prefix + ".require_nonempty", false);
        return std::make_unique<FlatDictionary>(database, name, dict_struct, std::move(source_ptr), dict_lifetime, require_nonempty);
    };
    factory.registerLayout("flat", create_layout, false);
}


}