Speed test: mysql query vs. file_exists()

I'm running a logs system where log entries are .log files with filenames like 03012002.log for January 3rd, 2002. You can view when logs have been posted with a calendar, which will make the particular day a link if that day's log file exists. I'm thinking of storing the log entries in a mysql database, using code somewhat like the following: $query = "select username, log, date_format(date, '%a %b %D') as date, from logs where username = $username"; $dates = mysql_db_query($bb_news_db, $query) or die("Select Failed!"); while ($row = mysql_fetch_array($dates)) { $date[row[$dates]]=1; } So that each log entry would be put in the $date[] array, and then when the calendar script wanted to find out if there was an entry by that user on that particular day, it would just have to check the $date[] array.Will there be any speed difference between this and my current (file_exists();) method?