Site hangs when saving usergroup permission

[Itek]

Hi all,

I have a forum with about 180K users in "Registered" group.

Since upgrading to VB5, whenever I try to save permission of this group, my site hangs immediately.

When I check the process after a while, I only see mysql running, it seems that the query getting a loop somewhere. So I have to restart mysql to make the forum available again.

Now what should I do, because I really need to change the group permission?

I opened a ticket (id 1336417) 3 days ago and almost no help. So I have to post here.

Anyone have a solution pls help me. Thank you!

[Guest]

Try to clear the cache in AdminCP first and then save the usergroup.

[Itek]

I did. Still the same...

[Itek]

I solved by truncating the cache table manually.

How to disable database cache? Because I'm using memcached.

Best regards.