InnoDB’s checkpoint algorithm is not well documented. It is too complex to explain in even a long blog post, because to understand checkpoints, you need to understand a lot of other things that InnoDB does. I hope that explaining how InnoDB does checkpoints in high-level terms, with simplifications, will be helpful. A lot of the simplifications are because I do not want to explain the complexities of how the simple rules can be tweaked for optimization purposes, while not violating the ACID guarantees they enforce.

A bit of background: Gray and Reuter’s classic text on transaction processing introduced two types of checkpoints beginning on page 605. There is a sharp checkpoint, and there is a fuzzy checkpoint.

A sharp checkpoint is accomplished by

As you probably know, I recently finished writing a book with a few co-authors. I kept notes along the way and wanted to describe the process for those who are thinking about writing a book, too.

Update: see the followup post for more of the story, including my editor’s responses.

I think it’s important to be objective; my purpose here is to help prospective authors get a feeling of what it’s like, and it’s not all good (but I’d encourage people to do it anyway). Hopefully I won’t come off as sounding peeved at anyone or like I’m trying to put people down. I’ll have a lot to say about what went right and wrong, and how it helped and hindered

Today is the first day at the conference (aside from the tutorials, which were yesterday). Here’s what I went to:

New Subquery Optimizations in 6.0

By Sergey Petrunia. This was a similar session to one I went to last year. MySQL has a few cases where subqueries are badly optimized, and this session went into the details of how this is being addressed in MySQL 6.0. There are several new optimization techniques for all types of subqueries, such as inside-out subqueries, materialization, and converting to joins. The optimizations apply to scalar subqueries and subqueries in the FROM clause. Performance results are very good, depending on which data you choose to illustrate. The overall point is that the worst-case subquery nastiness should be resolved. I’m speaking of WHERE NOT IN(SELECT…) and friends. It remains to be seen how

It's been a while since I said anything about the progress on the book. That doesn't mean we are not still working on it, though.

As Peter wrote a while ago, he is basically wearing the hat of a very advanced technical reviewer at this point. We've finished writing all the chapters from his detailed outlines. He has worked through about half the chapters, and I'm continuing to spend my evenings and weekends and holidays (yes, nearly all my free time -- just ask my wife!) writing some new material (an appendix on EXPLAIN, for example), finishing unfinished things marked with TODO in the text, and revising chapters after Peter reviews them. Vadim is working on benchmarks. For example, he just finished some benchmarks for

A while ago I asked for people and/or organizations to sponsor development on Maatkit (formerly MySQL Toolkit) so I could take a week off work and improve the Table Sync tool. I asked for $2500 USD, but several companies have graciously offered to cover that and then some.

I'm very happy about this, as it will allow me to dedicate a solid week to fixing bugs and adding features. There's a lot of demand for the tools, and there are a dozen or so bug reports unresolved for the table-sync tool, which I personally want to fix as much as anyone. So I'm very grateful for the support.

Here are the companies who have promised their financial support:

MySQL AB

We've begun writing the second edition of the now-classic High Performance MySQL. "We" means co-authors Arjen Lentz, Baron Schwartz, Vadim Tkachenko, and Peter Zaitzev. O'Reilly is still the publisher, and Andy Oram is still the editor. With a team like this, I think the second edition will be a book you don't want to miss. Though in theory we're revising the first edition, the truth is we're starting from scratch and re-writing the book, and significantly expanding it at the same time. A lot has changed since Jeremy and Derek wrote the first edition. Today's MySQL deployments push the limits further than many people thought possible a few years ago. We'll teach you how they do it.