Remove rows from a datatable worked very slow

Question

Hi together at first i get a big datatable from a oracle database (>100.000 items). In a second step i want remove items by filtercritera. But the way i remove the items worked very slow. Perhaps you can help me to find a faster way ;) Why i do it on this way: There is no way to get performant a smaler datatable direct from oracle. I hope there is a way to remove items fast from a datatable. Here the sourcecode: //Select useable items (works very fast) var useable = dataTable.Select((COLUMN1 IN (137)) AND ISNULL(DATECOLUMN1'2014-07-22 18:04:35Z') > '2014-07-16 18:04:35Z'); //List for the Items to delete var listToDelete = new List (); //Check is datarow useable (works very slow 120.000 items over 40 sec.) foreach (var rowItem in dataTable) { var found = useable.Contains(rowItem); if (!found) { listToDelete.Add(rowItem); } } //Remove items from dataTable (works very fast) foreach (var logisticDataRow in listToDelete) { dataTable.Rows.Remove(logisticDataRow); } i use .Net 4.0 VS 2010 cheers Guido

Ramesh Maruthi · Answer

Can you try with some extension methods to make it easier ... myTable.Delete((COLUMN1 IN (137)) AND ISNULL(DATECOLUMN1'2014-07-22 18:04:35Z') > '2014-07-16 18:04:35Z'); public static DataTable Delete(this DataTable table string filter) { table.Select(filter).Delete(); return table; } public static void Delete(this IEnumerable rows) { foreach (var row in rows) row.Delete(); } Otherwise create new datatbale using linq DataTable newDataTable = dt.AsEnumerable() .Where(r=> !useable.Contains(r.Field (COLUMN1))) .CopyToDataTable(); Otherway: List rowsToDelete = new List (); foreach( DataRow row in someTable.Rows ) { if( /* your condition here */ ) { rowsToDelete.Add( row ); } } foreach( DataRow row in rowsToDelete ) { someTable.Rows.Remove( row ); }