Yes, a Datareader is a connected stream--it can't be serialized or "sent"
anywhere. It would be like sending a firehose to someone in the mail.
Without the (live) connection to the data it's not of much use.
Yes, saving a lot of data in memory can be expensive but saving a reasonable
amount can be faster than refetching it from the database (requery). You
have to figure out a balance that works for your site. Some sites can't
afford to save much of anything (due to volume), but others can save quite a
bit as they don't support more than a few dozen clients at a time. I would
try the DataTable approach (which is far easier to do in the 2.0 Framework)
and see if the performance hit you're worried about really manifests itself.
hth
--
____________________________________
William (Bill) Vaughn
Author, Mentor, Consultant
Microsoft MVP
INETA Speaker
www.betav.com/blog/billva
www.betav.com
Please reply only to the newsgroup so that others can benefit.
This posting is provided "AS IS" with no warranties, and confers no rights.
__________________________________
"Chris Davoli" <(E-Mail Removed)> wrote in message
news:14C235F9-6243-4E2A-BFDA-(E-Mail Removed)...
> Well let me ask this question. I wite with n-tier components and the
> reason I
> want to get a dataset to a data reader is that I don't want to marshall
> and
> pass the data reader from a component (class that is instantiated) back to
> the aspx page. I know in classic asp this would take a performance hit. So
> I
> guess my question is, can datareaders be passed back from a data set with
> out
> a performance hit? I know they are cursors connected to the database until
> you close the, so won't I get a big performance hit if I marshall readers
> in
> memory?
>
> --
> Chris Davoli
>
>
>
> "W.G. Ryan - MVP" wrote:
>
>> Chris - if your db supports batch queries, just batch them up, specify
>> Table
>> and column mappings and let the adapter fill them.
>>
>> Technically a dataadapter uses DataReaders to fill tables so an Adapter
>> can't be faster than a reader. However to code the conversion, you need
>> to
>> check for DB null, infer the schema or know it beforehand , strongly type
>> the gets and everything else, all of which is a lot of work for a
>> performance gain that may not even be realized. Yes, depending on how
>> you
>> code the thing, you could come up with slower code using a reader than
>> you
>> otherwise would (use nominal lookups for instance and you'll shoot all
>> the
>> performance benefit right away). Also, you are taking the data from a
>> reader and storing it locally anyway, so in the scenario you describe, I
>> doubt you'll realize much performance benefit if any at all.
>>
>> If you're using the 2.0 Framework you can use dataTable.Load and pass in
>> the
>> reader. Otherwise you'll need to do
>> do{
>> while(dr.Read()){
>> DataRow dro = myDataTable.NewRow();
>> dro[0] = dr.Getxxx(0);
>> dro[1] = dr.Getxxx(1);
>> }
>> }while (dr.NextResult());
>> "Chris Davoli" <(E-Mail Removed)> wrote in message
>> news:62D5A478-0E61-407D-8286-(E-Mail Removed)...
>> > Environment: VB.Net, SQL Server 2000.
>> >
>> > I've used both data readers and also datasets with tables in them. I
>> > would
>> > like to use a data reader (because of its speed) to retrieve using a
>> > stored
>> > procedure with TWO selects in the stored proc (two result sets), then
>> > go
>> > thru
>> > the data reader and put both result sets into a DataSet as separate
>> > tables
>> > (table names). This will save me having to connect to the database
>> > twice
>> > and
>> > call two stored procs.
>> >
>> > Does anybody have an example of how to put a data reader into a data
>> > set
>> > as
>> > a table(s)?
>> >
>> > --
>> > Chris Davoli
>> >
>>
>>
>>
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