MVC ToDataSourceResult - query called twice?

[Brian Roth]

Hello,

We have an MVC application using Entity Framework as the interface into our database.  We recently added some database logging to our application in order to do some performance analysis.  I noticed that in the Read methods for our Kendo grids our SQL seems to be executing twice.  Drilling into this a bit more, I found that the Kendo.MVC.Extensions ToDataSourceResult() method against an IQueryable was the place where the double execution was happening.  A few of our queries take a fair amount of time to execute, so having them run twice is a performance drag.  I was hoping to get some help determining why this might be happening.  My best guess is that this is due to paging needing to find out the total row count and then a second execution to get the actual data, but it's only a guess.  If your team could help out, I'd really appreciate it.  Thanks!

Regards,
Brian

[Petur Subev]

Hello Brian,

The assumption that you shared is correct, we cannot get the total number of records without using the Count() extension method LINQ provides. The only way to optimize or change this default behavior is to create your own CustomBinding where you can use a session variable that holds the number of records.

result.Total = data.Count();
result.Data = data.Execute(selector);


Kind Regards,
Petur Subev
Telerik

 

 

[Brian Roth]

Hi Petur,

Thanks for the reply.  One further question - when you call the Count() method, do you do that on the IQueryable collection or do you convert it ToList first?

I really appreciate the help.  I'm going to look into the CustomBinding in the near future.  I think the hardest part for that would be implementing the filter logic.  Do you know if there are any plans to make public the filter methods that you are using in the ToDataSourceResult?

Regards,
Brian

[Petur Subev]

Hello Brian,

It is over the IQueryable interface (we do not use ToList() it will be a performance hit), you can check the complete implementation in the Extensions/QueryableExtensions.cs ToDataSourceResult method of the Kendo.MVC project.

I am not aware of such plans, you can check how the filtering implementation goes in the same project.

Kind Regards,
Petur Subev
Telerik

 

 

[Brian Roth]

Thanks!  I didn't realize the source code was available to look at.  That helps a lot.

Regards,
Brian