MySQL Bugs: #46032: Warn when using SBR with READ-COMMITED isolation level

Bug #46032	Warn when using SBR with READ-COMMITED isolation level
Submitted:	8 Jul 2009 7:44	Modified:	7 Sep 2009 2:31
Reporter:	Alon Lubin	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S4 (Feature request)
Version:		OS:	Any
Assigned to:	Luis Soares	CPU Architecture:	Any
Tags:	isloation level, read-commited, statement based replication

Description:
Currently,
READ-COMMITED isolation level requires RBR.
This causes replication overhead when this isolation level is reuired.

How to repeat:
Set isolation level to read-committed.
perform DML.

Many thanks for writing a feature request. We will check this.

What storage engine is used for the tables? If the DML is for InnoDB tables, it is not possible to fix since it the problem is inherent in how InnoDB tables work.

READ-COMMITTED isolation level is required when performing DML on InnoDB tables. For other tables, this should not be a requirement.

For more information, see BUG#23051.

We use InnoDB storage engine.
I saw BUG#23051

In our case, the database starts in READ-COMMITED and mixed-mode and there is no warning in the logs.

my.cnf parameters:

default_storage_engine=InnoDB
transaction-isolation = READ-COMMITTED
binlog-format=MIXED

We don't change the transaction and therefor do not get any errors/warnings.
I think the database should warn on startup about this configuration.

If I knew this on time, we would have make the application work with REPEATABLE-READ isolation level.

The replication overhead is a major problem for us now...

Thanks.

I totally agree with you here. Minimum of warning should happen.

Set back to verified.