I'm working with a store that runs on Magento EE 1.12. One day we opened up the store and found all the configurable products have gone missing from category listing. I inspected the SQL that loads the products and found out that the inner join with catalog_product_index_price had made it return empty.
I opened up the table and found out that while the child simple products of these configurable products are still in the table, the configurable products are not.
What could be causing this problem?