Safe to delete these fields?

[ultranerds]

Hi,

I'm not getting very far at all with tweaking the database on our site (now almost 2gb in size). I've noticed the "msgid" and "prefix" dont' seem to have a value for any of the "thread" entries;

SELECT * FROM thread WHERE msgid LIKE '%'
SELECT * FROM thread WHERE prefix LIKE '%'

...yields no results.

Is it safe to delete these fields? I'm not sure where exactly they are used, if anywhere.

TIA

Andy