compression in monetdb

Hai , Read that dictionary encoding occurs in monetdb . so 1) what is dictionary compression technique ? 2) Does it works for strings alone or other data structures too ? 3) I a mailing list it was stated that it works only till the size of the column in 128 MB for older release? Is this the same for current release ? 4) Does Monetdb uses any other compression technique ? 5) If yes where can I find the source of it (Precisely , which file in source ) Thanks in advance regards , Pradeep