I know this is not a specific answer to your question, but consider that by removing that database call, you are dramatically increasing your server load, increasing the size of each page and slowing down the responsiveness of your site.
Consider any page stackoverflow. Most of it is dynamic, so the page cannot be cached. but the users' thumbnail is static and can be cached.
If you send the thumbnail as a data URI, you are doing the DB lookup and data transfer for every thumbnail on every page.
If you send it as a linked image, you incur a single DB lookup for when the image is first loaded, and from then on it will be cached (if you send the correct HTTP headers with it), making your server load lighter, and your site run faster!