Suggestions for designing a app

Personally I'm using UUIDv4 to create unique customer ID's. It's not for security, but so that other customers can't guess how many documents, files, other customers there are in the system. You will still need to implement security measure to ensure that they only have access to their own data.

I'm storing it in BINARY as there are are a performance hit to JOIN table ID's as VARCHAR.

PHP Code:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

if ( ! function_exists('UUID_TO_BIN'))
{
    function UUID_TO_BIN($uuid) {
        $uuid = hex2bin(str_replace('-','',$uuid));
        return $uuid;
    }
}

if ( ! function_exists('BIN_TO_UUID'))
{
    function BIN_TO_UUID($uuid) {
        if( empty($uuid) ) return;
        $uuid = bin2hex($uuid);
        $uuid = substr($uuid, 0, 8) . '-' . substr($uuid, 8, 4) . '-' . substr($uuid, 12, 4) . '-' . substr($uuid, 16, 4)  . '-' . substr($uuid, 20);
        return $uuid;
    }
}


if ( ! function_exists('UUIDv4'))
{
    /**
     * Generates a random UUID using the secure RNG.
     *
     * Returns Version 4 UUID format: xxxxxxxx-xxxx-4xxx-Yxxx-xxxxxxxxxxxx where x is
     * any random hex digit and Y is a random choice from 8, 9, a, or b.
     *
     * @return string the UUID
     */
    function UUIDv4()
    {
        $bytes = random_bytes(16);
        $bytes[6] = chr((ord($bytes[6]) & 0x0f) | 0x40);
        $bytes[8] = chr((ord($bytes[8]) & 0x3f) | 0x80);
        $uuid = vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($bytes), 4));
        return $uuid;
    }
}

if ( ! function_exists('VALID_UUIDv4'))
{
    function VALID_UUIDv4($uuid)
    {
        return (bool) preg_match('/^[0-9A-F]{8}-[0-9A-F]{4}-4[0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}$/i',$uuid);
    }
}