The block should not get cached.
This setting should be used:
- For simple blocks (notably those that do not perform any db query), where
querying the db cache would be more expensive than directly generating the
content.
 
- For blocks that change too frequently.
 
Related topics
File
   - drupal/includes/common.inc, line 127
 
  - Common functions that many Drupal modules will need to reference.
 
Code
define('DRUPAL_NO_CACHE', -1);