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Slow Grid Scrolling
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agrogers View Drop Down
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Joined: 11-Mar-2010
Posts: 41 		Post Options Post Options   Quote agrogers Quote  Post ReplyReply Direct Link To This Post Topic: Slow Grid Scrolling
    Posted: 11-Mar-2010 at 5:51am
Hello

We found that a number of our DevEx 2009.2 grids were scrolling quite slowly and so began investigating the issue.  It became clear fairly quickly that once records in the grid had been viewed that section of the grid would then scroll very efficiently.  The data had of course been loaded into the cache.

However we have other grids where, even though we have viewed every record in the grid, the slowness of scrolling that grid remains.  Scrolling speed is returned to normal when I group by the columns that are joined to other tables so that only simple columns are shown in grid.  That suggests that the problem is with the grid traversing the entity graph to get other data.  But that doesnt make sense since it should already have that data in the cache and so it should be real fast.

Does anyone have any thoughts?

Thanks
Andrew
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IdeaBlade View Drop Down
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Joined: 30-May-2007
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Posts: 353 		Post Options Post Options   Quote IdeaBlade Quote  Post ReplyReply Direct Link To This Post Posted: 12-Mar-2010 at 10:20am
The usual reason for poor grid performance is indeed supplementary trips to the database to retrieve entities referenced in navigation properties which are not already in the cache. I'm not sure what might be causing your performance problems with the grid where you've already viewed the rows and therefore (presumably) already retrieved the related entities.
 
However, the solution to the standard problem may also solve your non-standard one: that being, to preload the data you're going to need (using a span query) before displaying the grid.  See, for example, the section "Span Queries" in the Object Persistence chapter in the Developers Guide.  There is also material in the Performance Tips powerpoint file in the Learning Units at
 
     LearningUnits\300 Advanced\Performance Tuning a DevForce App\01 Slides
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agrogers View Drop Down
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Joined: 11-Mar-2010
Posts: 41 		Post Options Post Options   Quote agrogers Quote  Post ReplyReply Direct Link To This Post Posted: 13-Mar-2010 at 4:20am
Thanks for your reply.  It turned out to be an issue related to running the application through Visual Studio.  We had tried both debug and release version but it didnt make any difference.  But when we launched the application from outside VS the scrolling work correctly and smoothly.

What caught us up was that sighting all records in some grids resulted in good scrolling and sighting all records in other grids made no difference.  Still dont know why that is but it is a good 'fix'.

Thanks for the performance tuning link.

Cheers
Andrew
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