I’m attempting to live blog corrections and notes while sitting in the replication tutorial. Lars is covering available options in MySQL replication. I’m going to attempt to cover some recommended best practices and things that are possible to do in MySQL but should be avoided. Please keep in mind that I’m writing this during the presentation. If anything is confusing post a comment and I will clean it up.

When designing a MySQL architecture that are several possible configurations. Two that should be avoided are dual master where you write to both masters. Configuring replication in a dual master dual writer setup means there is no single authority on the data. There is also no need to write to both masters as this doesn’t give you any performance improvement. Each master has to process the same sql statements. One step further is circular replication that wasn’t mentioned in the talk but has been in other publications. When using …

I woke up this morning to a nice surprise. Peter Zaitsev from MySQL Performance Blog mentioned my fix for a crash in MySQL. Thanks Peter! That reminded me that I need to write this post about another fix.

A storage engine is called a “handler” in MySQL internals. Handler events are per row at the storage engine layer. For example an insert query that inserts 3 rows will cause one Com_insert increment and 3 handler_write increments. The way these statistics are implemented the storage engine is responsible for incrementing statistics itself. Innodb is missing function calls to increment the handler_delete and handler_update status variables. I’ve filed …

While working with a client we found a query that can crash MySQL. It has to do with ref_or_null outer joins where the table contains a null value. MySQL fails to tell the storage engine to initialize the index before reading from it. It crashes when used with MyISAM tables but it could result in an incorrect key file for table error with other storage engines. You can find the test case and patch in bug #34945. I’ve waited to blog about it until MySQL approved my patch. As of this writing my patch has been approved and committed for release in 5.0.60.

My employer, both MySQL and Sun, will reimburse me for my internet connection.

I wonder if I could just buy FON routers for my favorite cafes, and then expense them? It would let me have better and more reliable internet access then I get thru the crappy little wireless routers from Quest and Comcast...

[Updated: 2008-03-05 Jeremy writes to tell that I left out the provenscaling.com contact form submission on the 21st and the blank email with a pdf on the 27th]
[Updated: 2008-03-26 Rob Young from MySQL AB sent me an email on the 17th saying, "We are currently working to implement PayPal to cut down on the email interactions we have in place around our manual fulfillment process. Testing is going well and we should have this implemented in the next few weeks."]

Recently Proven Scaling decided to purchase a MySQL Enterprise subscription. We will be evaluating Enterprise to see if it’s knowledge base is valuable to our customers as a supplement to Proven Scaling’s consulting services.

The subscription process seems remarkably manual on MySQL’s part. It involves them sending us five emails (not counting the mysql.com registration), all of which are from different senders. Some are from people others are automated. Here is a …

In Issue 3 of MySQL Magazine Peter Zaitsev writes, ” I would set [innodb_log_file_size] to 256 megabytes for small sized boxes up to 5% of the total memory on the big boxes.” I tend to set my log file size to around 128M. Depending on your system setting the log file size around a few hundred megs should be the right balance between preventing checkpointing and still having fast recovery times.

The manual states, “Sensible values range from 1MB to 1/N-th of the size of the buffer pool, where N is the number of log files in the group.” The sample my.cnf files that come with MySQL state to set the innodb_log_file_size to 25% of the innodb buffer pool size. I think this mistakenly advises people to set their log files much larger than they need to be causing unnecessarily long recovery times.

Crash recovery time is an important feature of InnoDB. In the event of a server crash large log files could mean waiting hours for …

When I received and email almost two years ago about a announcement that MySQL was going to release and enterprise product I was very excited. I was looking forward to a redhat style model of vetting releases in the community then offering a proven stable version to paying customers. I saw it as a great way to for MySQL to generate revenue as well as eliminate the need for people to stay a few releases back from the head and guess when to upgrade.

The release shocked me. What was originally emailed to me and the final plan were two very different things. It was a plan to hand paying customers bleeding edge code that had been tested only by MySQL’s QA team. It seems MySQL has forgotten the years of testing by millions of community members that has given MySQL the stability we have grown to trust. I predicted the instability of MySQL enterprise back in October ‘06 by saying that releasing patches in enterprise that hadn’t been tested by …

MySQL Bug Tracker

I realize that MySQL is in a transitional phase making it’s development more transparent to the community so this entry isn’t really a rant but something that will hopefully ease the transition. The public MySQL bug tracker doesn’t seem to have any way to view the history of status changes to a bug. Things like changing a bug from open to inactive. I assume there will always be things that should be hidden from bugs like links to sites internal to MySQL AB but things like simple status changes should be visible to the public.

For example on this Bug #20358 Heikki posted a comment that he was moving the bug from open to unable to repeat. Did he actually make the change? I have no idea because I can’t access the status log. Was it ever changed from unable to repeat back to open or verified? Again I have no idea…

Another …

In response to brad's post and daveman692's post, about Thoughts on the Social Graph.

I have posted the following:

I came home from FOOcamp with my mind buzzing with something similar. It was in the zeitgeist, I guess.

Between being annoyed at some of 6As recent actions, and annoyed that if I left LJ, I would lose a lot of valuable social network information. And then the sessions on distributed social networks, openid, …

Dear Lazyweb,

I have all my old .netscape and .mozilla directories for all my past installations of Netscape, Mozilla, and Firebox, going back to 1996. I've got cert.db, cert5.db, and cert7.db files.

I want to extract out all of the certs and keys that I had added to those databases, and then import them into my current ~/.mozilla database.

Reading the docs and futzing around with NSS signtool, certutil, and pk12util isn't getting me very far.

Surely there is a tool or technique do doing this...