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VirtualQueryableCollectionView + Grouping + Paging

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Data Virtualization
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Roy
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Roy asked on 12 Apr 2016, 08:29 AM

I'm currently evaluating my options for using RadGridView ( And maybe RadPivotGrid in the future ) in combination with large serverside datasets. For performance reasons we don't want to send the complete dataset to the client.

Therefore I'm now implementing a custom IQueryable provider that delegates grouping/paging/filtering to te serverside. For simple paging this works fine, I get simple Skip/Take requests on my IQueryable.

However when i start to use grouping I get a grouping request on my datasource, without any paging Skip/Take requests. This means that I should get all data from te server which is not acceptable for our solution.

What solution do you propose for this problem?

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Stefan
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answered on 14 Apr 2016, 08:59 AM
Hi Roy,

Can you please take a look at the Paging Before Grouping online example, or its WPF equivalent? Basically, the approach demonstrated in it consists of extending the default QueryableCollectionView by swapping the order in which the paging and grouping operations are processed.

Let me know whether this corresponds to your needs.

Regards,
Stefan X1
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Roy
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answered on 14 Apr 2016, 11:45 AM

Hi Stefan,

Thanks for your reply, unfortunately this doesn't realy solve my problem. My setup needs virtualization instead of real paging. It is important for the user to be able to scroll through all groups, and when requested expand a group an scroll throug al entries within a group.

With the data we have it is possible that we have a lot of groups, but also possible that we have lots of entries within a group.

To be able to manage the number of rows ( Wich can be in the millions ), we only want to get the rows visible on the screen. So when grouping i'd first like to do a request to the server for (e.g.) groups 0 to 20, that contain the key and the child count. When the group is expanded I want to get a paged result of the containing elements, and when scrolling getting the needed elements.

I hope you understand what it is that I'm trying to achieve.

 

Regards,

Roy

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Dilyan Traykov
Telerik team
answered on 19 Apr 2016, 11:32 AM
Hello Roy,

I'm afraid, there's no straightforward way to achieve the desired effect, as the VirtualQueryableCollectionView needs to first get all the items, in order to correctly group them.

We're sorry for any inconvenience caused.

Regards,
Dilyan Traykov
Telerik
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Stefan
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Roy
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Dilyan Traykov
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