Slow performance, slow and long running crons

On any Adobe Commerce version, because some extensions only work with flat tables there is a risk if you disable flat tables. If you know that you have some extensions that use Flat Catalog indexers, you may need to take that into consideration when setting those values to " No ".

This article describes how to solve site performance issues and slow running and stuck crons caused by flat tables and indexers having been enabled.


  • Adobe Commerce on cloud infrastructure 2.1.x and above
  • Adobe Commerce on-premises 2.1.x and above
  • Magento Open Source 2.1.x and above


Flat indexers can cause:

  • Heavy SQL load and site performance issues.
  • Long running and stuck crons.


Flat tables and indexers enabled.

Solution solution

Starting with Adobe Commerce and Magento Open Source 2.1.x and above, the use of a flat catalog is no longer a best practice and is not recommended. Continued use of this feature is known to cause performance degradation and other indexing issues. To disable the flat catalog:

  1. In the Admin, navigate to Stores > Settings > Configuration.

  2. In the panel on the left under Catalog , choose Catalog.

  3. Expand the Storefront section, and do the following:

    • Set Use Flat Catalog Category to No.
    • Set Use Flat Catalog Product to No.
  4. When complete, click Save Config. Then when prompted, refresh the cache.

  5. Flush cache by running php bin/magento cache:flush.

If you can’t change the Use Flat Catalog Category and Use Flat Catalog Product to No because the options are greyed out, disable flat indexers in app/etc/config.php:

  1. Run this command to make sure all indexers are set to Update by schedule: php bin/magento indexer:set-mode schedule.
  2. Edit app/etc/config.php and locate the lines with flat_catalog_product and flat_catalog_category - change them from 1 to 0 to disable them.
  3. Run the command php bin/magento app:config:import
  4. Run this command to confirm that the flat indexers are disabled: php bin/magento indexer:status.
  5. Flush cache by running php bin/magento cache:flush.

Reset stuck Adobe Commerce cron jobs manually on Cloud in our support knowledge base.