I keep bumping into this as I ponder my own project. I don't know how the big guys do this. Is a SKU typically unique to each product size? Like say Macy's has a bunch of men's shirts. Does each size carry it's own SKU?
It seems like the easiest approach is a hybid (and they get great gas mileage too, lol). From a front end perspective it almost has to be separate tables. It seems rather daunting to pull from a single table yet offer all color and size options as drop downs. On the other hand the ONLY way to manage inventory is the single table. The inventory table could be sparse. In other words not every combination would be listed only those with stocking inventory. If a previously unstocked combination was purchased the SKU could be formed by concatenating the product and price options. Like a men's dress white shirt in 3XL might be MDWH3XL.
I don't know, just typing out loud. What do you think of a hybrid approach? Can you see any issues? Is it just a bunch more work or might this help?