Remove rows from a datatable worked very slow

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 (1,3,7)) 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

Can you try with some extension methods to make it easier ...

myTable.Delete("(COLUMN1 IN (1,3,7)) 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 );

}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Ramesh Maruthi12y ago
Can you try with some extension methods to make it easier ...

myTable.Delete("(COLUMN1 IN (1,3,7)) 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 );
}