Function convertBlockStructure

src/Interpreters/DirectJoin.cpp:28–63

Converts `columns` from `source_sample_block` structure to `result_sample_block`. Can select subset of columns and change types.

/// Converts `columns` from `source_sample_block` structure to `result_sample_block`.
/// Can select subset of columns and change types.
static MutableColumns convertBlockStructure(
    const Block & source_sample_block, const Block & result_sample_block, MutableColumns && columns, const PaddedPODArray<UInt8> & null_map)
{
    MutableColumns result_columns;
    for (const auto & out_sample_col : result_sample_block)
    {
        /// Some columns from result_sample_block may not be in source_sample_block,
        /// e.g. if they will be calculated later based on joined columns
        if (!source_sample_block.has(out_sample_col.name))
            continue;

        auto i = source_sample_block.getPositionByName(out_sample_col.name);
        if (columns[i] == nullptr)
        {
            throw DB::Exception(ErrorCodes::NOT_FOUND_COLUMN_IN_BLOCK, "Can't find column '{}'", out_sample_col.name);
        }

        ColumnWithTypeAndName col = source_sample_block.getByPosition(i);
        if (!col.type->equals(*out_sample_col.type))
        {
            col.column = std::move(columns[i]);
            result_columns.push_back(IColumn::mutate(castColumnAccurate(col, out_sample_col.type)));
        }
        else
        {
            result_columns.push_back(std::move(columns[i]));
        }
        columns[i] = nullptr;

        if (result_columns.back()->isNullable())
        {
            assert_cast<ColumnNullable *>(result_columns.back().get())->applyNegatedNullMap(null_map);
        }
    }
    return result_columns;
}

DirectKeyValueJoin::DirectKeyValueJoin(std::shared_ptr<TableJoin> table_join_,
                                       const Block & right_sample_block_,