Aperture Database too large

I have an aperture library which is over 300GB! When I 'get info' on package contents of the library i get the following results(approximated):
Thumbnails: 11 gb
Previews: 5 gb
Masters: 79 gb
iMovie-Thumbnails: 195 mb
Database: 275 gb
...
How come my aperture database is 3 times larger than my masters, previews, and thumbnails combined! I dont have that much space to waste. Any help is appreciated.

One more thing...the history.apdb file is the problem(contains 99% of the database contents at 274gb)

 

Solved

After prowling around the web to no success, I just decided to rebuild my library. That worked .