Re: Performance better with DataSet or DataReader or ...???

From: gwenda (nina_at_community.nospam)
Date: 11/15/04 

Date: Mon, 15 Nov 2004 09:50:03 -0800

Hi Kevin and Dave,
First, let me thank you for your answers which were very helpful. I
especially liked the idea of exposing parts of the DS through my properties.
Second, let me clear one issue just to make sure we understand each other. I
mentioned in my previous message that my objects are filled in the data layer
and then being sent to the client (through a business layer and a service
layer). So in any case I wasn’t planning to leave an open connection to the
DB from the client. The connection is opened; the object is filled; and the
connection is closed. Since dataReaders usually perform better than DS, I
thought it would be better to use it – for example:

public MyClass GetMyClass(int myClassID)
{
          const string procName = "P_Get_MyClass_By_ID";
          MyClass myClass = null;
          SqlParameter[] sqlParameters = new SqlParameter[]{new
SqlParameter("@myClass_ID", myClassID)};
  using (SqlDataReader myClassReader =
SqlHelper.ExecuteReader(connectionString,CommandType.StoredProcedure,
procName, sqlParameters))
          {
                    while (myClassReader.Read())
                                                            {
                                                                       
if(myClass == null)
                                                                       {
                                                                             
   myClass = new MyClass (myClassReader.GetInt32(0),
myClassReader.GetString(1), new DataSet("contactsList"));
                                                                       }
                                                             }
          myClass.childrenCollection.Tables.Add("Children");
          
myClass.childrenCollection.Tables["Children"].Columns.Add("Favorite_color",
System.Type.GetType("System.String"));
          
myClass.childrenCollection.Tables["Children"].Columns.Add("Speed"),
System.Type.GetType("System.String"));
          if(myClass.NextResult())
                                        {
                                                  while (myClassReader.Read())
                                                  {
                                                            
myClass.childrenCollection.Tables["Children"].Rows.Add( new
object[]{myClassReader.GetString(0), clientReader.GetString(1)});
                                                  }
                                         }
          }
}
 
Following your answers, I understand this code is harder to maintain but I
want to be sure that performance-wise its better too – taking into account
that the connection is not kept open through the whole client session.
 
Thank you both again,
Gwenda

"Dave Fancher" wrote:

> Sorry for not getting this back yesterday. It sounds like you may still
> have an opportunity to rework your schema a bit but without the schema I
> can't really give you any guidance on that (and depending on your progress
> on the project it might not be an option).
>
> I'd like to extend on what Kevin has said below. If you populate a DataSet
> with the two result sets returned from your stored procedure you will
> definately reduce the load on your DB Server (but, since you're using MSDE,
> I doubt it would make much difference overall). Also consider this though:
> It doesn't sound like you really need to manage the relationship with the
> DataSet because (from my understanding of you're previous posts), you're
> going to populate the private fields of your class with the parent's
> information, then reference the children through the dataset.
>
> If this is the case, If you only have the one "Collection" you can just
> replace the DataSet field with a DataTable field and call the copy() method
> of the DataTable in your DataSet to copy the DataTable into your class. You
> could then dispose of your data set and get rid of the overhead it causes.
> Furthermore, you stated that you were using the DataSet to "track what was
> changed in them by the user," The individual data tables are responsible
> for managing the changes, not the DataSet.
>
> If you do, indeed have multiple "Collections" you should probably follow
> Kevin's advice and use the DataSet with DataRelations but rather than
> populate member fields in your class, just create properties that expose
> only what needs to be exposed. For example:
>
> public class MyClass
> {
> private DataSet peopleInfo;
>
> public int ID
> {
> get { return (int)(peopleInfo.Tables["Parent"].Rows[0]["ID"]); }
> }
>
> public string Name
> {
> get { /* code to get the name here */ }
> set { /* code to set the name here */ }
> }
>
> public DataTable Children
> {
> get { return peopleInfo.Tables["Children"]; }
> }
> }
>
> I hope this helps
>
> "Kevin Yu [MSFT]" <v-kevy@online.microsoft.com> wrote in message
> news:NV6JseUyEHA.2916@cpmsftngxa10.phx.gbl...
> > Hi Gwenda,
> >
> > First of all, I would like to confirm my understanding of your issue. From
> > your description, I understand that you need to know the best way to fill
> > the childrenCollection DataSet. If there is any misunderstanding, please
> > feel free to let me know.
> >
> > In my opinion, I will try to fill the two tables to a single DataSet and
> > create a DataRelation between two tables. We can use GetChildRows to get
> > the children table rows according to the parent ID and put them to the
> > objects. This will help to lower the workload of database server, since a
> > DataReader will require an open connection to the database. If many
> > clients
> > will connection to the server simultaneously, this would be a good
> > practice. It does all the object filling at client side.
> >
> > Kevin Yu
> > =======
> > "This posting is provided "AS IS" with no warranties, and confers no
> > rights."
> >
>
>
>

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