Magento no longer recommends the use of a flat catalog as a best practice. Continued use of this feature is known to cause performance degradation and other indexing issues. A detailed description and solution is available in the Help Center.
Affected versions include:
- Magento Commerce Cloud 2.1.x and above
- Magento Commerce (On-Premise) 2.1.x and above
- Magento Open Source 2.1.x and above
Source: https://docs.magento.com/m2/ce/user_guide/catalog/catalog-flat.html
Above link referes to another help page: https://support.magento.com/hc/en-us/articles/360034631192
Issue Flat indexers can cause:
Heavy SQL load and site performance issues. Long running and stuck
crons.
Why is this best practice for large catalogs reversed? Is the heavy SQL load and site performance issues new? Or is it a risk which always was present?
Are there any changes on this topic in the codebase since 2.1.x and above?
