Forum Search is missing a lot of my old threads?

[محروم.كوم]

It looks like when I moved from 3.8.5 to 4, my search is missing lots of pertinent data (like everything from 2005 through 2009)? Do I need to rebuild the search index? Forum has 800K posts...sounds like this will bring a lot of servers to a halt New threads are being shown...so are 2004 threads and older.




Thanks for any advice. __DEFINE_LIKE_SHARE__