Function tryGetColumnFromBlock

src/Interpreters/getColumnFromBlock.cpp:16–40

}

ColumnPtr tryGetColumnFromBlock(const Block & block, const NameAndTypePair & requested_column)
{
    const auto * elem = block.findByName(requested_column.getNameInStorage());
    if (!elem)
        return nullptr;

    auto elem_type = elem->type;

    if (!elem->column)
        return nullptr;

    auto elem_column = elem->column->decompress();

    if (requested_column.isSubcolumn())
    {
        auto subcolumn_name = requested_column.getSubcolumnName();
        elem_column = elem_type->tryGetSubcolumn(subcolumn_name, elem_column);
        elem_type = elem_type->tryGetSubcolumnType(subcolumn_name);

        if (!elem_type || !elem_column)
            return nullptr;
    }

    return castColumn({elem_column, elem_type, ""}, requested_column.type);
}

ColumnPtr tryGetSubcolumnFromBlock(const Block & block, const DataTypePtr & requested_column_type, const NameAndTypePair & requested_subcolumn)
{