How to increase open files limit for a specific user?

Question

Currently we have below entry in /etc/security/limits.conf

* hard nofile 65000

I want to increase that limit for a specific user called oracle, so if I add a line below like

oracle hard nofile unlimited which one will have precedence?

Also does increasing this specific limit require more resources in the server? I am making this change because the server is reaching current limit 65000 open files. And I am getting too many open files in the system error message when I try to login. An oracle database is hosted on the server. Is it required to bounce the database or reboot the server after making this change?

Answer 1

The man page man limits.conf states:

In general, individual limits have priority over group limits, so if you impose no limits for admin group, but one of the members in this group have a limits line, the user will have its limits set according to this line.

So, the user specific rule would take precedence over the default. You would need to restart the services for the changes to take effect as the limits are per session.

Increasing the limit does not necessarily require more resources. It would be useful to run some benchmarks if you are worried about performance, so you can identify where the bottlenecks are, if any.