What is the faster way to access a DataTable/DataRowsCollection? - performance

Question

I have a datatable with 100,000+ DataRow. Which method is faster to access the collection?
Is there any faster way to process the rows collection ?
Method 1:
var rows= dsDataSet.Tables["dtTableName"].Rows;
int rowCount = dsDataSet.Tables["dtTableName"].Rows.Count;
for (int c = 0; c < rowCount; c++)
{
var theRow = rows[c];
//process the dataRow
}
Method 2:
for (int c = 0; c < dsDataSet.Tables["dtTableName"].Rows.Count; c++)
{
var theRow = dsDataSet.Tables["dtTableName"].Rows[c];
//process the dataRow
}

Answer 1

It is worth noting the most direct way to access cells is via the DataColumn indexer; the data is actually stored in the columns, not the rows (no: really).
So something like:
var table = dataSet.Tables["dtTableName"];
// HERE: fetch the DataColumn of those you need, for example:
var idCol = table.Columns["Id"];
var nameCol = table.Columns["Name"];
// now loop
foreach(DataRow row in table.Rows)
{
var id = (int)row[idCol];
var name = (string)row[nameCol];
// ...
}
However, frankly if you want the best performance, I would start by saying "don't use DataSet / DataTable". That is actually a very complicated model designed to be all kinds of flexible, with change tracking, rule enforcement, etc. If you want fast, I'd use a POCO and something like "dapper", for example:
public class Foo {
public int Id {get;set;}
public string Name {get;set;}
}
...
string region = "North";
foreach(var row in conn.Query<Foo>("select * from [Foo] where Region = #region",
new { region })) // <=== simple but correct parameterisation
{
// TODO: do something with row.Id and row.Name, which are direct
// properties of the Foo row returned
var id = row.Id;
var name = row.Name;
// ...
}
or even skip the type via dynamic:
string region = "North";
foreach(var row in conn.Query("select * from [Foo] where Region = #region",
new { region })) // ^^^ note no <Foo> here
{
// here "row" is dynamic, but still works; not quite as direct as a
// POCO object, though
int id = row.Id; // <=== note we can't use `var` here or the
string name = row.Name; // variables would themselves be "dynamic"
// ...
}