I want to make page which inserts a new post (in a new thread) by its parameters, such as

testinsert.php?title=XXX&body=YYY&user=123&key=ZZZ

(it's for a robot that posts breaking news)

The way to go would then be:
* find the largest ID
* insert new post with
** inserted ID = largest ID+1
** PID = 0
** TID = inserted ID
** UNIQID = either empty or some random string
** rest are self explanatory
(&key=ZZZ is just a password so no one else can abuse this. nothing to do with the DB)

Should I insert this in mlf2_entries only, or also in mlf2_entries_cache?

Are there other concerns I should take into consideration?

I guess that it's possible that during the split second between I find the largest ID and I post this as largest ID+1, another post could have been made. But that's just so darn unlikely that it's not worth worrying about ...