MySQL hang during "show collation" on Amazon RDS
Not sure if you found a solution to this but for us it seems to be related to the size of data leaving the VPC.

If you run a query with a small result set:

show collation like '%utf8_swedish%';


The result returns fine, but if you take away the like and get a large result set back it fails. We're still investigating the problem but not sure you found a solution.