title: Will existing indexes be affected when changing character_set and collation of MySQL db
body: <ol>
  <li>We have an database where the default character set for tables and columns is set to <strong>utf8</strong> encoding</li>
  <li>But with character set encoding of <strong>utf8</strong> , we are unable to save emojis</li>
  <li>To support saving of emojis, 
     a) We had to change the character set of table and columns to <strong>utf8mb4</strong>
     b) We had to change the collation of table and columns to utf8mb4_unicode_ci
     c) Update our JDBC driver so that it supports the unicode encoding</li>
  </ol>
  
  <p>With the above changes we are able to save the emoji in our columns.</p>
  
  <p><strong>Question:</strong>
  1) Do I need to delete existing indexes (varchar columns) and recreate the indexes as earlier with utf8 each character used to take 3 bytes and now with utf8mb4 encoding it will occupy 4 bytes ?</p>