Jan Wieck wrote:
> On 9/14/2007 3:10 PM, Dmitry Koterov wrote:
>> MySQL has the "binary log" to which all data is appended before it is 
>> committed to the real table. All MySQL replicas are simply replaying 
>> this binary log from a specified position, so it is quite close to 
>> what Slony does (but Slony uses its own event log, not built-in as in 
>> MySQL). Seems an asynchronous statement-based replication does not 
>> exists in the world at all.
>
> According to the MySQL 5.1 manual
>
>     http://dev.mysql.com/doc/refman/5.1/en/binary-log.html
>
> it contains statements. Seems people aren't exactly sure what a 
> statement is in MySQL land.
>
> Then again:
>
> "The format of the events recorded in the binary log is dependent on 
> the binary logging format. Three format types are supported, row-based 
> logging, statement-based logging and mixed-base logging. The binry 
> logging format used deoends on the MySQL version. For more information 
> on logging formats, see Section 5.11.4.1, “Binary Logging Formats”."
>
> Which is as best confusing. So different versions support different 
> logging formats, and they are not all available at the same time? And 
> what the heck is mixed-based? 
If you use for example the NDB engine, which is used in MySQL Cluster, 
MySQL chooses to switch to ROW based statement to provide replication 
between 2 different clusters.
> Have MySQL (which is known to make pretty bad judgments when it comes 
> the integrity and consistency of YOUR data) chose when to aim for row 
> based and when statement based might be "faster"?
>
> Further down it explains that writes to the log are handled like 
> MyISAM writes. Which doesn't really mean much to me, but maybe someone 
> can tell if that means that a transaction, done and committed against 
> InnoDB tables, could be recovered in a server crash situation but lost 
> from the "binary log"? Or is that something 100% guaranteed 
> impossible? The manual isn't quite clear about that.
Binary Log is not guaranteed to be written on disk cause it uses the 
filesystem cache as MyISAM does. So the situation you described can happen
>
>
> Jan
>

-- 
Cyril SCETBON