The latest from the MySQL community

I’ll be presenting a free one-hour webinar on preventing downtime in production MySQL servers, in conjunction with the ODTUG. It is scheduled on Thursday, November 10, 2011 3:00 PM – 4:00 PM EST, and you can register for free.

Here’s an abstract of what you’ll learn:

Everyone wants to prevent database downtime by being proactive, but how effective are the common measures such as inspecting logs and analyzing SQL? To be truly proactive, one must prevent problems, which requires studying and understanding the reasons for downtime. We have analyzed a selection of emergency issues that we have solved, to better understand what types of problems really occur in production environments. The results are somewhat surprising, and will be detailed in this talk. Most incidents we found were not MySQL-specific and will be familiar to Oracle DBAs as well as …

A few people have asked me how it’s going, so I thought I’d just share it with everyone. Things are going great. I’m writing much more quickly than I thought I would be, and as a result I’m finding I have time to do more changes than I thought I could, which makes me happy. I should be finished drafting the chapters by the end of the year.

In particular, the faster than expected pace is giving me a chance to address one of the big weaknesses of the second edition. In many places, the second edition is a collection of facts and experiences. It says what and why, but it doesn’t convey a process or method, and it doesn’t teach you how to think about things and apply the results to situations beyond what the book covers. I’m finding a number of key areas to remedy that: performance optimization, profiling, indexing, high availability, scalability, and so on. I’m adding an explanation of the principles and consequences, and …

I had some conversations with a few people at Oracle Open World about features that would be beneficial in InnoDB. They encouraged me to blog my thoughts, so I am.

Someday I’d like to have a clear mental list of features I want in MySQL in general, but that is a much harder list to organize and prioritize. InnoDB is an easier place to get started.

First, I’d like truly online, nonblocking DDL. I see two ways this could work: reading the old version of rows and writing the new version, or doing a shadow-copy and building the new table in the background. The first way has the advantage of being lazy, so the schema change is instantaneous, and you really never pay any additional cost. However, it has the disadvantage that it might be hard to implement multiple schema changes if a previous change isn’t fully finished, so to speak (I can see a lot of bugs if there are more than 2 versions of the schema at a time). This is a …

I was looking into the history about why SYSDATE() and NOW() behave differently in MySQL, and it looks like in 4.0 and 4.1 they used to be the same. But as of MySQL 5.0, SYSDATE() was changed to emulate Oracle’s behavior, that is, it returns the time as of the function execution, not as of the statement start.

There are a number of bug reports related to this: 15101, 12480, 12481, and 12562.

I am not an Oracle expert. Does NOW() return a constant result within an Oracle query, like NOW() in MySQL does? Or is there no NOW() in Oracle, and you use SYSDATE() instead? Why is Oracle’s SYSDATE() functionality worth emulating? It looks to me like some …

I’ve been seeing a few occasions where Neil J. Gunther’s Universal Scalability Law doesn’t seem to model all of the important factors in a system as it scales. Models are only models, and they’re not the whole truth, so they never match reality perfectly. But there appear to be a small number of cases where systems can actually scale a bit better than linearly over a portion of the domain, due to what I’ve been calling an “economy of scale.” I believe that the Universal Scalability Law might need a third factor (seriality, coherency, and the new factor, economy of scale). I don’t think that the results I’m seeing can be modeled adequately with only two parameters.

Here are two publicly available cases that appear to demonstrate this phenomenon: Robert Haas’s recent blog post on PostgreSQL, titled …

This year’s Surge conference was a great sophomore event to follow up last year’s inaugural conference. A lot of very smart people were there, and the hallway track was great.

I presented on three things: a lightning talk about causes of MySQL downtime; I chaired a panel on Big Data and the Cloud; and I showed how to derive scalability and performance metrics from TCP traffic. I’ve sent my slides to the Surge organizers, and I understand that they will be posting them as well as integrating them into the video of my session. In the meanwhile you can download my slides from Percona’s presentations page.

Further Reading:

• I’m speaking at Surge 2011
…

“I want to ensure that the MySQL code base (under the name of MariaDB) will survive as open source, in spite of what Oracle may do.” -- Michael “Monty” Widenius. Michael “Monty” Widenius is the main author of the original version of the open-source MySQL database and a founding member of the MySQL AB company. [...]

A special extended edition of Tech Messages for 2011-08-31 through 2011-09-21:

• Lab Overview
  This guy is serious about his lab!
• Throughput
  All sorts of useful information here. My favorite is the first table which includes bandwidth and packet throughput for different kids of circuits.
• Must see: 5 Steps to Scaling MongoDB (Or Any DB) in 8 Minutes
  These tips are relevant no matter what database system you are using.
• Understanding and …

Two of my proposals for Percona Live London on October 24-25 have been approved! Yes, I really had to propose them and get them approved like everyone else, although as I’m sure you can imagine, I had a good chance at being accepted :-) Not all of my talks were accepted, though.

I’ll be presenting a half-day tutorial on how to get great results when troubleshooting MySQL problems, and a conference session on how to use TCP packet headers to measure and analyze a surprising variety of aspects of MySQL performance and scalability.

The …

I’ve never objected to someone making money from MySQL. I’ve only expressed disappointment that they weren’t doing it effectively enough. As I have predicted many times, Oracle is good at this. Oracle is the number one reason I didn’t start a new career in some other database a few years ago. Oracle is making MySQL more successful not only for Oracle, but also for the users, the community, and the competition.

I am glad that Oracle is offering more pay-only extensions to the server in a way that creates opportunities for others to do the same, and I look forward to even more of them in the future.

Further Reading:

• …