Create Unique Image Names

Question

What\'s a good way to create a unique name for an image that my user is uploading?

I don\'t want to have any duplicates so something like MD5($filename) isn\'t suita

Answer 1

For good performance and uniqueness you can use approach like this:

• files will be stored on a server with names like md5_file($file).jpg

• the directory to store file in define from md5 file name, by stripping first two chars (first level), and second two (second level) like that:

  uploaded_files\ 30 \ c5 \ 30 c5 67139b64ee14c80cc5f5006d8081.pdf

• create record in database with file_id, original file name, uploaded user id, and path to file on server

• on server side create script that'll get role of download providing - it'll get file by id from db, and output its content with original filename provided by user (see php example of codeigniter download_helper ). So url to file will look like that:

  http://site.com/download.php?file=id

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Pros:

• minified collisions threat

• good performance at file lookup (not much files in 1 directory, not much directories at the same level)

• original file names are saved

• you can adjust access to files by server side script (check session or cookies)

Cons:

• Good for small filesizes, because before user can download file, server have to read this file in memory