The first problem is that although porcelain is repairable, is it worth it? If you have a seamless, uniform table top, it can be filled and repaired by an epoxy process but will not be perfect unless the entire top is completely recoated. If you are referring to porcelain tiles with joints or seams, maybe it is best to remove the tiles and re-tile the top.
Furniture restoration can be very expensive due to the amount of labor involved. The restored oak "bottom" may be damaged by removal of porcelain, even under the most delicate method of removal. Unless the table is an heirloom, you may want to consider a glass overlay in one of many tints and types of edges, or replacing the entire top. Otherwise, save your money and get a beautiful new table for the same money and a lot less aggravation. Bon Appetit!