Bug #73823 Logs flooded by default with new 'Note' level items
Submitted: 6 Sep 2014 9:10
Reporter: Andrew Hutchings Email Updates:
Status: Open Impact on me:
None 
Category:MySQL Server: Logging Severity:S4 (Feature request)
Version:5.7.4 OS:Any
Assigned to: CPU Architecture:Any

[6 Sep 2014 9:10] Andrew Hutchings 
Description:
By default 'Note' level logging is enabled on MySQL server.  This is great, there are many useful things in this.  One thing that isn't useful is:

"[Note] Aborted connection .... (Got an error reading communication packets)"

This happens every time an idle connection is disconnected without gracefully sending COM_QUIT first.  Multiple this up by hundreds of connections per second and the log file explodes in size.  This creates a potential performance problem (and probably a disk usage problem over time).

How to repeat:
1. connect to the MySQL server using the command line client
2. killall mysql

Suggested fix:
1. If the connection is idle, don't log this.  MySQL should be able to handle clients not exiting cleanly anyway without any problem.  It should also know when we have received the first packet and therefore in a command state and therefore this is a legitimate log line.

or

2. If a log line is repeated X times in quick succession then just output that the previous message was repeated X times, much like syslog.