Example:
I have an image with this url: “/images/mario-profile-photo.jpeg”.
Change the url to: “/images/mario-profile-photo.jpeg?updated={DateTime.Now.Ticks}“.

So, I lied, sorry! This will make the browser request the image again, because the url is different. It doesn’t really refresh the cache.

Using DateTime.Now.Ticks will force the refresh every time the page loads, so I don’t recommend using it.

If you have the time of when the photo was last updated, use that instead! Something like: {Photo.UpdateDate.Ticks}
This way, you will only request a new image when it is different from the one you already have in cache.

Note: the “?updated=” property is just a name, you can use whatever you want. The important thing is to modify the url.

For Umbraco developers: When saving an image, do not forget to set it’s UpdateDate! Umbraco doesn’t update that property automatically.

Hope this helps,
Thanks for reading!
Mário

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As for any caching mechanism, it is possible that the BLOB cache becomes out-of-sync with the content database, storing an old version of a file that has been updated in the content database.

The quickest way to re-sync the BLOB cache is to flush it and let SharePoint repopulate it with the current version of the binary files. Flushing the BLOB cache can only be done through a PowerShell script (since there is no place for it on the SharePoint UI):

$webApp = Get-SPWebApplication "<WebApplicationURL>"
[Microsoft.SharePoint.Publishing.PublishingCache]::FlushBlobCache($webApp)
Write-Host "Flushed the BLOB cache for:" $webApp

In which <WebApplicationURL> is the URL address of the web application for which you want to flush the BLOB cache.

You can find additional information in: http://technet.microsoft.com/en-us/library/gg277249.aspx

The post Flushing the BLOB cache in SharePoint 2010 appeared first on Blog IT.