Would it hurt the system performance too much to store log data in both a text file and a database. The plain text file will be good for if the database crashes or the application dies (reading log information from inside phpmyadmin can't be good). Storing the logs in a database as well would be good to integrate into the backend of the application so the admins can search and sort the log in a nice user interface.

But would it hurt system performance to much to be performing mysql queries and writing to a file on a regular basis? Or should it be alright?