MySQL Bugs: #28603: Invalid log-bin default location

Bug #28603	Invalid log-bin default location
Submitted:	22 May 2007 20:32	Modified:	19 Feb 2008 13:59
Reporter:	BJ Dierkes	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Replication	Severity:	S2 (Serious)
Version:	5.0.41	OS:	Linux (Redhat Enterprise Linux ES 4 - i386)
Assigned to:	Andrei Elkin	CPU Architecture:	Any
Tags:	bfsm_2007_10_18

Description:
Operating System: Red Hat Enterprise Linux ES release 4 (Nahant Update 5)
Arch: i386

The default location for 'log-bin' does not appear to be correct as of version 5.0.41.  Referencing the MySQL documentation:

http://dev.mysql.com/doc/refman/5.0/en/binary-log.html

"When started with the --log-bin[=base_name]  option, mysqld writes a log file containing all SQL commands that update data. If no base_name value is given, the default name is the name of the host machine followed by -bin. If the basename is given, but not as an absolute pathname, the server writes the file in the data directory. It is recommended that you specify a basename; see Section B.1.8.1, “Open Issues in MySQL”, for the reason."

This would imply that if 'log-bin' is implicitly set in my.cnf (just setting 'log-bin' without '=base_name'), that the binary log will be output to '/var/lib/mysql/<hostname>.XXXXXX'.  However, as of 5.0.41 the log is output to '/var/run/mysqld/mysql-bin.XXXXXX'.  If *explicitly* set, the log outputs to '/var/lib/mysql/<base_name>.XXXXXX' as expected.

Please note that I did read 'http://dev.mysql.com/doc/refman/5.0/en/open-bugs.html'; and did not find anything that sounds relative.

In summary, if log-bin is not explicitly configured for a specific log 'base_name', the default 'datadir' is *not* used and the binary log is created in '/var/run/mysqld'.  The following show both configurations:

With log-bin explicitly configured:

[rpm-dev@rhel-i386-es-4_test ~]$ date
Tue May 22 15:19:46 CDT 2007

[rpm-dev@rhel-i386-es-4_test ~]$ cat /etc/my.cnf | grep log-bin
log-bin=myserver

mysql> SHOW MASTER STATUS;
+-----------------+----------+--------------+------------------+
| File            | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+-----------------+----------+--------------+------------------+
| myserver.000001 |       98 |              |                  | 
+-----------------+----------+--------------+------------------+
1 row in set (0.00 sec)

[rpm-dev@rhel-i386-es-4_test ~]$ ls -lah /var/lib/mysql/myserver.000001 
-rw-rw----  1 mysql mysql 98 May 22 15:19 /var/lib/mysql/myserver.000001

With log-bin implicitly set:

[rpm-dev@rhel-i386-es-4_test ~]$ date
Tue May 22 15:09:41 CDT 2007

[rpm-dev@rhel-i386-es-4_test ~]$ cat /etc/my.cnf | grep log-bin
log-bin

mysql> SHOW MASTER STATUS;
+-------------------+----------+--------------+------------------+
| File              | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+-------------------+----------+--------------+------------------+
| mysqld-bin.000003 |       98 |              |                  | 
+-------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

[rpm-dev@rhel-i386-es-4_test ~]$ ls -lah /var/run/mysqld/mysqld-bin.000003 
-rw-rw----  1 mysql mysql 98 May 22 15:10 /var/run/mysqld/mysqld-bin.000003

The severity is marked as Serious as this issue breaks replication when upgrading to MySQL 5.0.41 (if log-bin is not explicitly set with a base_name).

How to repeat:
Set 'log-bin' in /etc/my.cnf without '=base_name'.  Restart MySQL and verify binary log location.  In this case, the log is output to '/var/run/mysql' and not '/var/lib/mysql'.

Suggested fix:
If no base_name is supplied, the logfile should be created as '<hostname>-bin.XXXXXX' in the datadir (/var/lib/mysql).

Sorry.. perhaps the original Synopsis having 'Bogus' in there caused this one to be over looked...  

Any input on this issue?

Thank you for the report.

Verified as described.

How to repeat see bug #28850

Two issues:
1. log name default to mysql-bin instead of hostname.
   it's documentation problem
2. default location. fixed by a patch for BUG#28597

The bug was fixed by BUG#28597 patch.
The latter also preserved a way how binlog file name was constructed (after fixes
for bug#20166).
"Fixed with preserving`pidfile_name' (intr.by bug@20166) but stripping
  off its directory part."
Therefore there are no more issues, incl documentation, wrt this bug.
Documentation team, please confirm and close.

Discussed bug and fix with Andrei; noted in the changelog entry for Bug #28597 that the fix for that bug also fixes this one. 

Added note to -The Binary Log- section in the 5.0/5.1/6.0 Manual advising of the server versions affected by these 2 bugs.

Closed bug report.