DataTable.Select and Performance Issue in C#

Question

I\'m importing the data from three Tab delimited files in the DataTables and after that I need to go thru every row of master table and find all the rows in two child tables

Answer 1

You can speed it up a lot by using a dictionary. For example:

if (distinctdt.Rows.Count > 0)
{
    // build index of C1 values to speed inner loop
    Dictionary masterIndex = new Dictionary();
    foreach (DataRow row in rawMasterdt.Rows)
        masterIndex[row["C1"].ToString()] = row;

    int count = 0;
    foreach (DataRow offer in distinctdt.Rows)
    {

Then in place of

    string exp = "C1 = " + "'" + offer[0].ToString() + "'" + "";
    DataRow masterRow = rawMasterdt.Select(exp)[0];

You would do this

DataRow masterRow;
if (masterIndex.ContainsKey(offer[0].ToString())
    masterRow = masterIndex[offer[0].ToString()];
else
    masterRow = null;