Product attribute keeps being "null" in flat table

Question

I'm having a magento installation with flat product tables activated. As I need an attribute in collections I've set it to "Used in Product Listing", the rest is a pretty simple textfield for all products not visible in frontend. The problem I encounter is that in flat tables this attribute isn't set whereas another attribute with all options set in backend to the same settings works as expected.

Re-Indexing doesn't make a difference (besides holding the server cpu hostage ;))

Answer 1

It turned out that somehow the tables got corrupted and instead of "int" it said "varchar" in the eav_attribute table for "backend_type" - therefore the indexer was searching in the wrong table (catalog_product_entity_int vs catalog_product_entity_varchar)

Answer 2

My problem was that someone had changed SKU to be "Used in Product Listing": "No"... Should be yes to be stored in flat..