#27685
else if (!nullable_src && nullable_dst)
    {
        if (change_lowcard)
            dst_column = makeNullable(changeLowCardinality(src_column, dst_not_null));
        else
            dst_column = makeNullable(src_column);
    }
    else 
    {
        if (change_lowcard)
        {
            if (const auto * nullable = checkAndGetColumn<ColumnNullable>(*src_column))
            {
                dst_column = makeNullable(changeLowCardinality(nullable->getNestedColumnPtr(), dst_not_null));
                assert_cast<ColumnNullable &>(*dst_column->assumeMutable()).applyNullMap(nullable->getNullMapColumn());
            }
            else
                dst_column = changeLowCardinality(src_column, dst_not_null);
        }
        else
            dst_column = src_column;
    }
}
ColumnPtr emptyNotNullableClone(const ColumnPtr & column)
{
    if (column->isNullable())
        return checkAndGetColumn<ColumnNullable>(*column)->getNestedColumnPtr()->cloneEmpty();
    return column->cloneEmpty();
}
ColumnRawPtrs materializeColumnsInplace(Block & block, const Names & names)