Tuesday Oct 14, 2008

STATEMENT based replication as default in MySQL 5.1

MySQL 5.1.29, the next (and last) release candidate, will revert the default replication mode to STATEMENT based. As noted in Bug#39812, MIXED mode won't be the default anymore. But the template option files provided with the distribution will have a line that enables MIXED mode.

The rationale for this change is that MIXED mode as default may break existing applications, where statements like the following are used:


UPDATE t1 SET a=1 WHERE @@server_id = 1;
INSERT INTO t1 (origin, val) @@server_id , 1;

We know that several users are exploiting the quirks of STATEMENT based replication to their advantage. So we decided that it was safer not to force MIXED mode on users who are upgrading.

Instead, we added MIXED mode to the option files templates, to encourage new users to start with MIXED mode.

We are very eager to boost the adoption of MIXED base replication, but we are also concerned about mismatches and would like to avoid unpleasant surprises for users who switch from 5.0 to 5.1.

Please notice that this change is not aiming at making MySQL 5.1 master servers compatible with 5.0 slaves. The manual warns explicitly against using lesser versions for slave servers, and the rationale of this change has nothing to share with mixed versions usage.

Update : fixed the master/slave mixup.

Tuesday Oct 07, 2008

The Proxy belt - Designing fail safe systems webinar

There is a free webinar today, October 7, at 10am PDT (1pm EDT, 7pm CEST, 5pm UTC), about Designing Fail-Safe Systems with MySQL Proxy.

It's an interesting session to attend, for several reasons.

  • Building a fail safe systems is the dream (and the nightmare) of every system architect. There are many solutions, not all of them are viable.
  • This solution was implemented by a user, Clint Alexander, Internet Technologist for the Army Game Project.

The interesting part is that this session is not a theoretical disquisition, but a detailed technical and practical description of how to achieve fail safe in a heavy duty web project.

In addition to the presenter, there will be several MySQL engineers as panelists, so you will be able to ask questions and get answers from the top experts.

And what is the Proxy belt? That's a teaser for you. It's an interesting technological concept that has been probably been done already, but this is the first time that someone has actually tried it out in practice. The name is a cute description of what has been implemented. You will get the real info and a catchy picture in the presentation.

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Giuseppe Maxia

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