If your oscommerce store is a particularly large one, and you are constantly adding new ranges of products, ading specials and lots of different products attributes, you will eventually encounter the 1104 MAX_JOIN_SIZE error on your product listing pages.

This is somethng I recently came across myself on a site with around 1500 individual products with dozens of associated product attribute variations

There are many reasons why you should consider regularly backing up your oscommerce database, not least of all the fact that sooner or later there is a good chance that you may suffer a partial or complete loss of data.

This may be due to your webhost having server problems, modules or contributions you have added yourself, a corrupt database, or the need to move your oscommerce site to a new server.

I have to add a post to praise and publicise the fantastic work of the team at open-source-services and their fantastic oscommerce module (PaPs)V2.0 PLUS