Do you know that there are two limits about dirty (modified but not flushed to disk) blocks of InnoDB buffer pool? One is the limit of "amount". The other is the limit of "age".

-- limit of "amount" --

As you know, buffer pool of InnoDB works as write-back cache of its datafiles. If the buffer pool is filled by dirty blocks, InnoDB cannot allocate new blocks without flushing the dirty blocks and the performance would get worse. This is the limit of dirty block "amount". We can avoid this limit by setting 'innodb_max_dirty_pages_pct' smaller or setting the larger buffer pool size. We might be never at a loss about the limit.

The another limit we should understand is limit of dirty block "age".

-- limit of "age" --

As you know again, because InnoDB write the modifies of datafile to transaction log file synchronously, InnoDB is allowed to treat its buffer pool as write-back …

I just uploaded one of my chapters in my book "Developing Web Applications using Perl, Memcached, MySQL and Apache" (Wiley). This was the 50% point. Man, this is a ton of work. Writing a book really takes up every second of your life, which is really hard when there are other projects you maintain - namely DBD::mysql, Memcached UDFs, FederatedX and my interest in helping with Drizzle. I've tried as much as possible to use my projects as material for the book making it possible to do two things at once, as well as make it interesting to write.

It's harder to write on reference material and explaining basic concepts than it is to write about code examples. The code examples I really enjoy because they are first interesting, and secondly there are some tricks and code functionality (particularly with Perl, DBI, stored procedures, etc) that I have never tried out before despite having been writing code for many years, that this book has …

I just finished reading the recently released 2nd Edition of High Performance MySQL by Baron Schwartz, Peter Zaitsev, Vadim Tkachenko, Jeremy Zawodny, Arjen Lentz & Derek Balling.  I’ve posted a review here on Amazon.

Wow, that’s quite a list of authors, but when you look at the material, you see why.  This book is a very indepth look at the MySQL server.  Intended for the intermediate to advanced DBAs and developers who want to know the inner workings of the server, as well as how to use many of it’s advanced features.

For instance the chapter on replication was quite good.  Given that you probably setup replication in five minutes, and are wondering weeks or months later why it’s not working, this chapter will give you …

In this month’s Database Journal article  we write about Replication Pitfalls with MySQL.

Replication is fairly straightforward to setup, however your slave databases can get out of sync, or throw errors.  We investigate some of the reasons why, and help you identify those before they come back to bite you!

The Umlaut Problem - How To Successfully Back Up And Restore MySQL Databases With Special Characters Using MySQLDumper

There are lots of forums with heaps of reports of umlauts or other special characters being displayed erroneously. Attempts to help come from many sides, but hardly anyone seems to have a really complete picture of the problem. Even web hosts' support hotlines seem to reach their limit of knowledge with this one. There are incredible amounts of half-truths. They prove correct in certain circumstances, but they do not help all people. Simply because setups vary so much. In my role as developer of MySQLDumper I naturally spent a lot of time evaluating this situation. And I now believe to be able to offer a complete overview which covers the different aspects of this problem. A lot, and I mean a lot of research has gone into the explanations in this article.

I rarely use MySQL Fulltext indexes. Their performance is just not good enough, so often its better to just stick with "LIKE" or move to something else like Sphinx, Lucene etc. The only nice thing about them is the ability to compute a match "rank". Well anyways I had to write a new search plugin for a project that is based around MySQL Fulltext indexes and a match rank and all as well .. except that for some reasons some words just would not produce any results. As I was trying to find a pattern I finally noticed that in my test data some words were used in most rows and exactly those were not matching. Obviously it makes sense to exclude automatically any words that have a very high hit ratio. And indeed the documentation states that by default …

As consumer spending slows across the world, a variety of "brick and mortar" retailers are clearly feeling the impact. Foot traffic is slowing, and it's getting harder to balance debt laden real estate portfolios and fickle consumer trends.

For consumer product manufacturers, retail distribution is key - it's how you get in front of a customer. It's why the big PC manufacturers are all working hard to score deals with big retailers (or build their own retail outlets) around the world.

But making money on PC's is tough - for most PC makers, you're remarketing someone else's operating system and someone else's microprocessor - it's not for the faint of heart (or faint of balance sheet). For Sun, our retail distribution concerns don't surround consumer hardware (we don't make PC's) as much as consumer software - the popularity of which defines our market opportunity. …

Daniel (aka Mr. Messina of Malaysia) is organising a bunch of events, and since they’re on weekends, I’m going to gladly participate, without seeking approval from the overlords.

First up is Startup Camp KL, on 22-23 November 2008, in MidValley. On Sunday, I’m going to lead a session titled “Using Free Software to bootstrap your startup”. Check out the agenda. It should be fun, especially in today’s market to ensure there are no software licensing costs, especially if you’re a startup.

Then there’s BarCampJB, 6-7 December 2008, in Johor Bahru. I haven’t been there in…. ages :) I’ll be talking about “MySQL Best Practices for Developers”, where we’ll go …

Well this is awesome:

The flash version has an eight times larger capacity of 4TB, starting at 320GB and consists single level cell (SLC) NAND flash. Its latency is around 23 times slower at 70 microseconds. It supports more than 100,000 sustained random write IOPS and 200,000 read IOPS (4K blocks) and can do so for ten years. According to Violin, users would need 500 15,000 rpm Fibre Channel drives to deliver this level of performance.

The biggest barrier to running MySQL/InnoDB on a device like this is that it’s going to be 100% CPU bound.

My advice to the guys at Fusion IO or Violin is to give/loan one of your lower end machines to Percona, MySQL AB, or even just reach out to one of the alpha geeks.

Of course over time this stuff will just get fixed.

Your devices are going to be …

As you likely have seen Sun has posted the new SpecJAppServer Results More information from Tom Daly can be found here These results are quite interesting for me as I worked on some of the previous SpecJAppServer Benchmarks several years ago while being employed by MySQL.

These are great results, plus they can be relevant to a lot of us because commodity x86 based hardware was used for the test. So it is not just about Sun it is about OpenSource hardware on Commodity Hardware.

As usually with results from such benchmarks there is no direct comparison available. The configuration Tom compares results to are not OpenSource and on the hardware of the different class so it is really hard to see what really caused the difference. It would be very interesting to …