Question

I have a performance bottleneck on a DataView.Sort. The code is below.

    /// <summary>
    /// Filters the data table and returns a new data table with only the filtered rows.
    /// </summary>
    /// <param name="dtInput">The dt input.</param>
    /// <param name="filterExpression">The filter expression.</param>
    /// <returns></returns>
    protected virtual DataTable FilterDataTable(DataTable dtInput, string filterExpression)
    {
        DataTable result = dtInput;
        if (!string.IsNullOrEmpty(filterExpression) && filterExpression.Trim().Length > 0)
        {
            DataView view = new DataView(dtInput);
            view.RowFilter = filterExpression;
            view.Sort = HierarchyFieldMap.DisplayedValue;
            result = view.ToTable();
        }
        return result;
    }

Any idea’s on how to improve this method?

It takes ~1 second to execute.

EDIT

I found this link on DataView’s Poor Peformance with Large RecordSets

Answer 1

Since you’re not returning a DataView but a DataTable, you should be able to get a performance boost – not order-of-magnitude, but 25-30% – by using DataTable.Sort:

private static DataTable SortDataTable(DataTable t, 
   string filterExpression,
   string sortExpression)
{
    DataTable t1 = t.Clone();
    t1.BeginLoadData();
    foreach (DataRow r in t.Select(filterExpression, sortExpression))
    {
        t1.Rows.Add(r.ItemArray);
    }
    t1.EndLoadData();

    return t1;
}

Most of the time that’s being taken up there is copying the data into the new table. If you can avoid creating a new table and work with the array of DataRows that DataTable.Select returns you can get a considerable improvement.