title: PHP unique identy field in url
body: <p>I have dilemma. I need unique string in my database table to show it in url (I don't show id in url).</p>
  
  <p>I want generate in php unique string check it is unique in table if not generate new.</p>
  
  <p>What do you think in terms of performance for a string with a length of 8 characters, and with a large number of rows (about 100,000 rows).</p>