Is it faster to upload and download images into a MongoDB than on disk

Question

Say we want to develop a photo site.

Would it be faster to upload or download images to or from MongoDB than store or download images from disk... Since mongoDB can save images and files in chunks and save metadata.

So for a photosharing website, would it be better (faster) to store the images on a mongodb or on a typical server harddisk. etc.

im thinking of using php, codeigniter btw if that changes the performance issues regarding the question.

Answer 1

Lightweight web servers (lighttpd, nginx) do a pretty good job of serving content from the filesystem. Since the OS acts as a caching layer they typically serve content from memory which is very fast.

If you want to serve images from mongodb the web server has to run some sort of script (python, php, ruby... of course FCGI, you can't start a new process for each image), which has to fetch data from mongodb each time the image is requested. So it's going to be slow? The benefits are automatic replication and failover if you use replica sets. If you need this and clever enough to know to achieve it with FS then go with that option... If you need a very quick implementation that's reliable then mongodb might be a faster way to do that. But if your site is going to be popular sooner or later you have to switch to the FS implementation.

BTW: you can mix these two approaches, store the image in mongodb to get instant reliability and then replicate it to the FS of a couple of servers to gain speed.

Some test results.

Oh one more thing.. coupling the metadata with the image seems to be nice until you realize the generated HTML and the image download is going to be two separate HTTP requests, so you have to query mongo twice, once for the metadata and once for the image.