join_buffer_size

Hello,

  1. Is it true that if my table join is using index, then this value is meaningless?

  2. On the other hand, what value should I set? Assuming I have 4GB of main memory and do a lot of large table join.

  3. The mysql tunning script (www.day32.com/MySQL) said more than 4MB is not advised, is it too conservative?

Many Thanks.