Creating a hashed upload directory structure in wordpress for sites with large amounts of files

The problem:

A website has over 2.4 million uploads in WordPress within one month. The location was exceptionally sluggish due to the overwhelming number of files in a single directory. There are 2 million files within wp-content/uploads/2019/07.

After searching around, I surprisingly found no plugin that addressed this issue. So, I decided to write something for this client. I came across https://codex.wordpress.org/Plugin_API/Filter_Reference/upload_dir which demonstrated how to change the upload folder. I used this to create a setup where two random letters are generated while keeping the standard upload folder structure intact. In this case, wp-content/uploads/2019/07 becomes wp-content/uploads/2019/ 07/a/b.

A random pair of letters, chosen from a to z, is generated twice to form the new upload folder.

To activate this plugin on the client website, I created a file called upload_file_hash.php under wp-content/mu-plugins with the following code:

<?php
/*
Plugin Title: upload folder hash
Description: Hash the upload folder for a large amount of files using https://codex.wordpress.org/Plugin_API/Filter_Reference/upload_dir
Creator: John Quaglieri
Version: 1.0.0
Creator URI: http://webhostingpeople.internet
*/

function upload_folder_hash( $param ) {
$letter = chr(rand(97,122));
$letter2 = chr(rand(97,122));
$folder = ‘/’ . $letter . ‘/’ . $letter2;
$mydir = $folder;
$param[‘path’] = $param[‘path’] . $mydir;
$param[‘url’] = $param[‘url’] . $mydir;
return $param;
}

add_filter(‘upload_dir’, ‘upload_folder_hash’);

Once completed, all new uploads in the media will use the new folder structure. Problem solved.