Method readKeys

src/Interpreters/DictionaryReader.cpp:113–157

}

void DictionaryReader::readKeys(const IColumn & keys, Block & out_block, ColumnVector<UInt8>::Container & found,
                                std::vector<size_t> & positions) const
{
    auto working_block = sample_block.getColumnsWithTypeAndName();
    size_t has_position = key_position + 1;
    size_t size = keys.size();

    /// set keys for dictHas()
    ColumnWithTypeAndName & key_column = working_block[key_position];
    key_column.column = keys.cloneResized(size); /// just a copy we cannot avoid

    /// calculate and extract dictHas()
    function_has->execute(working_block, size);
    ColumnWithTypeAndName & has_column = working_block[has_position];
    auto mutable_has = IColumn::mutate(std::move(has_column.column));
    found.swap(typeid_cast<ColumnVector<UInt8> &>(*mutable_has).getData());
    has_column.column = nullptr;

    /// set mapping form source keys to resulting rows in output block
    positions.clear();
    positions.resize(size, 0);
    size_t pos = 0;
    for (size_t i = 0; i < size; ++i)
        if (found[i])
            positions[i] = pos++;

    /// set keys for dictGet(): remove not found keys
    key_column.column = key_column.column->filter(found, -1);
    size_t rows = key_column.column->size();

    /// calculate dictGet()
    for (const auto & func : functions_get)
        func.execute(working_block, rows);

    /// make result: copy header block with correct names and move data columns
    out_block = result_header.cloneEmpty();
    size_t first_get_position = has_position + 1;
    for (size_t i = 0; i < out_block.columns(); ++i)
    {
        auto & src_column = working_block[first_get_position + i];
        auto & dst_column = out_block.getByPosition(i);
        dst_column.column = src_column.column;
        src_column.column = nullptr;
    }
}

Block DictionaryReader::makeResultBlock(const NamesAndTypesList & names)
{