I'm having trouble getting a custom module to install and update successfully. I'd like to examine the database for the modules update_N numbers. Is that possible? If it is, where do I look for it?


They're in key/value storage, which in the database would be the key_value table. Look for entries with a collection of system.schema, and a name matching the machine name of the module you're interested in.

Through the API, it's a bit easier:

$current_version = drupal_get_installed_schema_version('name_of_module');
  • Thanks, Clive - Perfect! One thing still puzzels me though; when I uninstall then install the module the version number is restored to the higest _N in the install file and the install hook is run but none of the update_N functions are executed. I'm guessing that maybe I could reset the version using the uninstall hook. Any thoughts on this? Thanks --- Mike – Mike Feb 10 '16 at 15:38
  • When you install a module, none of the hook_update_N() is invoked. Storing the higher update value is the right action Drupal does. – kiamlaluno Feb 10 '16 at 17:08
  • Update hooks are not for when a module is installed. For that, there is hook_install(), which is executed every time a module is installed, as in Drupal 7. – kiamlaluno Feb 10 '16 at 17:09
  • 1
    Yeah, what @kiamlaluno said. Think of hook_update_N as the way to get older versions of your module up-to-speed with the current codebase when it changes. For new installs, the current state of the module and any data it stores should be inline with what hook_update_N would have taken an older version to if it was upgraded – Clive Feb 10 '16 at 18:03
  • My instincts would have it different but as long as it's consistent that works too. Thanks for the insights. – Mike Feb 10 '16 at 19:02

There is another possibility as pointed in the documentation

You could use drush and run the following command:

drush php-eval "echo drupal_get_installed_schema_version('module_name');"

to find the last applied update hook for a specific module.

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