Function isAlreadySorted

src/Interpreters/sortBlock.cpp:391–418

}

bool isAlreadySorted(const Block & block, const SortDescription & description)
{
    if (block.empty())
        return true;

    ColumnsWithSortDescriptions columns_with_sort_desc = getColumnsWithSortDescription(block, description);
    bool is_collation_required = false;

    for (auto & column_with_sort_desc : columns_with_sort_desc)
    {
        if (isCollationRequired(column_with_sort_desc.description))
        {
            is_collation_required = true;
            break;
        }
    }

    size_t rows = block.rows();

    if (is_collation_required)
    {
        PartialSortingLessWithCollation less(columns_with_sort_desc);
        return isAlreadySortedImpl(rows, less);
    }

    PartialSortingLess less(columns_with_sort_desc);
    return isAlreadySortedImpl(rows, less);
}

}