Why isnt pageSize parameter offered for IStatement prototype of ISession.Execute

Question

I see that we can call:

      public RowSet ExecuteRowSet(string statement, int? pageSize = null)
    {
        return pageSize.HasValue ? _session.Execute(statement, pageSize.Value) : _session.Execute(statement);
    }

but we cannot call:

      public RowSet ExecuteRowSet(BoundStatement statement, int? pageSize = null)
    {
        return pageSize.HasValue ? _session.Execute(statement, pageSize.Value) : _session.Execute(statement);
    }

Why is pageSize not provided for a BoundStatement?

Answer 1

If you want to use a page size, you can use the SetPageSize method on the statement class. So for a bound statement, this might look like:

boundStatement = boundStatement.SetPageSize(100);
RowSet rows = session.Execute(boundStatement);

// Now iterate over the RowSet and subsequent pages will be loaded transparently as needed by the enumerator
foreach(Row row in rows)
{
   // Do something
}

Note: this is to take advantage of the automatic paging feature in the driver and not for manual paging scenarios like showing a paging UI in an application. The other overload you mention is just a shortcut/convenience method for quickly executing CQL and optionally using automatic paging. It's basically equivalent to doing:

var simpleStatement = new SimpleStatement("SELECT * FROM sometable");
simpleStatement.SetPageSize(100);
RowSet rows = session.Execute(simpleStatement);

Hope that helps.