Method joinImpl

src/Interpreters/NestedLoopJoin.cpp:229–386

}

void NestedLoopJoin::joinImpl(
    const ExpressionActionsPtr & actions,
    const String & filter_name,
    Block & left_block)
{
    Block new_block;
    std::unordered_set<std::string> left_column_names(left_block.columns());
    for (size_t i = 0; i < left_block.columns(); i++)
    {
        left_column_names.emplace(left_block.getByPosition(i).name);
    }

    for (size_t left_row_index = 0; left_row_index < left_block.rows(); left_row_index++)
    {
        if (right_blocks.empty())
            break;

        auto index = 0;
        BlockFilterDescriptions block_filter_descriptions;
        for (Block right_block : right_blocks)
        {
            paddingRightBlockWithConstColumn(left_block, left_row_index, right_block);
            actions->execute(right_block, false);
            auto filter_column = right_block.getByName(filter_name).column->convertToFullColumnIfConst();
            auto filter_and_holder = std::make_shared<FilterDescription>(*filter_column);
            auto filtered_size = countBytesInFilter(*filter_and_holder->data);
            block_filter_descriptions.add(index, right_block, filter_and_holder, filtered_size);
            index++;
        }

        auto total_filtered_size = block_filter_descriptions.getTotalFilteredSize();

        if (is_left && total_filtered_size == 0)
        {
            if (new_block.columns() == 0)
            {
                auto filter_and_holder = block_filter_descriptions.getHolderByIndex(0);
                auto right_block = block_filter_descriptions.getBlockByIndex(0);
                for (size_t i = 0; i < right_block.columns(); ++i)
                {
                    auto & right_col = right_block.getByPosition(i);
                    if (isConstFromLeftTable(right_col, left_column_names))
                    {
                        auto & left_col = left_block.getByName(right_col.name);
                        auto new_column = left_col.type->createColumn();
                        new_column->insertFrom(*left_col.column, left_row_index);
                        new_block.insert({std::move(new_column), left_col.type, left_col.name});
                    }
                    else
                    {
                        auto new_column = right_col.type->createColumn();
                        new_column->insertDefault();
                        new_block.insert({std::move(new_column), right_col.type, right_col.name});
                    }
                }
                continue;
            }
            else