[jet rex]

I have a big size of databases hat I wrote in first post.
I think a big size overload mysql and i want to clean it - delete old info.
optimize/repair I did from AdminCP every 2 days - but it not help
for example of error

Database error in vBulletin 3.8.4:

Invalid SQL:

					UPDATE subscriptionlog
					SET status = 1,
					pusergroupid = 2,
					regdate = 1288646280,
					expirydate = 1296595080
					WHERE userid = 154680 AND
						subscriptionid = 16;

MySQL Error   : Lost connection to MySQL server during query
Error Number  : 2013
Request Date  : Monday, November 1st 2010 @ 09:18:10 PM
Error Date    : Monday, November 1st 2010 @ 09:18:32 PM
Script        : http://mydomain.com/admincp/subscriptions.php?do=status
Referrer      : http:/mydomain.com/admincp/subscriptions.php?do=adjust&subscriptionid=16&s=
IP Address    : xxx.xxx.xxx.xxx
Username      : admin
Classname     : vB_Database_MySQLi
MySQL Version :