searching for files from a single folder (knowing prefix) versus searching for files from multiple folders (knowing folder name)

Question

Hi!

I've got a system in which users select a couple of options and receive an image based on those options. I'm trying to combine multiple generated images(corresponding to those options) into the requested picture. I'm trying to optimize this so that if, an image exists for a certain option (i.e. the file exists), then there's no need to compute it and we move on to the next step.

Should I store these images in different folders, where each folder is an option name? Should I store them in the same folder, adding a prefix corresponding to the option to each image? Should I store the filenames in a database and check there? Which way is faster to check a file for existence?

I'm using PHP on Linux, but I'm also interested if the answer varies if I change the programming language or the OS.

Answer 1

If you're going to be producing a lot of these images, it doesn't seem very scalable to keep them all in one flat directory. I would go with a hierarchy, which will make it a lot easier to manage.

It's always going to be quicker to check in a database than to check if a file exists though, so if speed is the primary concern, use a hierarchical folder structure and keep all the filenames in a database.