When you are using dynamic collections with PivotViewer i.e. JIT collections generated using the PivotServerTools, there comes a situation when the Pivot Viewer stops taking the fresh data from the server. This is because the Pivot Viewer caches the collection, so when you reload the collection again (in the same session), it doesn’t ask the JIT server for the cxml again and instead uses the cxml from the cache. This is good in terms of the performance however it’s bad if your data keeps on updating at the server and you are not able to reflect the latest data in your collection. What you should know is that the PivotViewer caches the collection based on the URL that you pass in the PivotViewer’s LoadCollection method, so if you call the method:

PivotViewer.LoadCollection(“url”, “viewerstate”);

again and again without changing the url parameter, only for the first call data will be fetched from your server, for all subsequent calls PivotViewer will take the collection from the cache. To avoid this, you have to keep changing the URL, whenever you call the above method. The best way to do it, is to add a query string parameter which you may/may not use and update it every time you load the collection. You can do something like below:

PivotViewer.LoadCollection(“url”+ “?guid=”+Guid.NewGuid(), “viewerstate”);

this adds a new query string parameter “guid” to your url who’s value change every time you load the collection and since it’s a different url, PivotViewer doesn’t find the collection in its cache and hence sends a call to the JIT server to get the new collection. Therefore, you will always see fresh data in your collection but what you should keep in mind is that this will degrade the performance of the PivotViewer (but only at the time of loading), so what you can do as a further tweak is only change the guid parameter when you need fresh data in your collection and in all the other cases you can use the url with the same guid parameter which will help in keeping the performance of the PivotViewer intact, this tweak will be a boon if your JIT server takes time for generating the collection and the data is not updated always.

Happy Coding :)

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