mysql binlog format

Hiya

I run master - master replication for my MySQL replication setup.

Ive just upgraded to Mysql 5.1 and as a result im seeing the following
in my syslog.

'Statement may not be safe to log'

Ive been reading up on the following.
http://dev.mysql.com/doc/refman/5.1/en/replication-sbr-rbr.h tml

http://www.slideshare.net/ligaya/mysql-51-replication
(See from slide 12.)


The question I would like to ask is. Is it safe to just change the
binlog format? Or is a preprocedure that needs to first be exercised.
With the above warning, is this something I can ignore, or is there a
serious matter (silly question I know, but I felt I needed to ask it).
After reading the above urls, im still stuck as to which binlog format
to use. Im leaning toward mixed, but the part of its still testing is a
little nerving.
And then lastly, if the change is made, and something goes wrong. Is
there a role back procedure, or can I just change the binlog format back
to STATEMENT.

If anyone can help me understand this, it would greatly be appreciated.

Kind Regards
Brent Clark

--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?unsub=gcdmg-mysql-2@m.gmane.org

Re: mysql binlog format

----- Original Message -----
> From: "Brent Clark"
>
> 'Statement may not be safe to log'

Heh. Some of those statements weren't particularly safe in previous versions, either, but they didn't whine :-p

Roughly, what it comes down to is that statements that contain things that may be different on master and slave at the respective time of execution might replicate differently. For some things (like date() calls) this is solved by replacing them with a constant before they get logged (now() is replaced with the actual timestamp, for example), while for other things (unORDERed selects) it may not be a simple.

Row logging is another take on it: instead of logging the statement, it logs the actual changes, thereby neatly sidestepping the problem. This brings other issues, though.

> The question I would like to ask is. Is it safe to just change the binlog format? Or is a preprocedure that needs to first be
> exercised.
> And then lastly, if the change is made, and something goes wrong. Is there a role back procedure, or can I just change the binlog
> format back to STATEMENT.

AFAIK, the log format is automatically detected by the slave, so there should be no problem in switching between the two (well, three) forms. The very existence of Mixed format logging is actually proof of that, in a sense :-)

If "something goes wrong", however, it's a reasonable assumption that your replication got messed up, so it's highly recommended to reinitialize the slave at that point, as wel as changing back to statement-based logs.



--
Bier met grenadyn
Is als mosterd by den wyn
Sy die't drinkt, is eene kwezel
Hy die't drinkt, is ras een ezel

--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?unsub=gcdmg-mysql-2@m.gmane.org