I'm normalising a large Table which can extend to 3-4 million rows. One of the fields is 'Year' (eg '2017'). There are up to 80 different years in the database and obviously many are repeated many times, Is it worth indexing this field?
I can make a table with a primary key and the related year, such as y1 = 2000, y2 = 2001, y3 = 2002 and so on, then relate the primary key to year field in the main Table. I'm just wondering whether all this fuss for so little is worthwhile. Is it going to make a performance improvement? Or should I be doing this a completely different way.