Number of open files

Hi,

I am having problems with the number of open files on Redhat 6.1. The value
of /proc/sys/fs/file-max is 4096 (the default), but this value is reached
with about 50 ODBC connections. Increasing the file-max value would only
temporarily improve matters because on the long-term I expect to have 500+
active connections. How comes there are so many open files per connection?
Is there any way to decrease the number of open files, so that I don't have
to increase file-max to immense proportions?

Thanks,
Mark.