From the performance point of view, logging to a file is *much* (much!) faster than writing to a database. But, of course, it depends on the volume of incoming data. With rsyslog queued modes, you can also write massive amounts of messages into the database, even if you server is not fast enough to handle it

Here are the details:
http://www.rsyslog.com/doc-rsyslog_high ... _rate.htmlRainer
PS: To remain honest, the server must be capable of handling the message volume at some time.

But it must not be capable to handle it immediately. Messages may be queued for some hours...