This is a friendly reminder to check the publication date and discussed version you MySQL books before starting out hacking or even posting about limitations. Lots of old books are still going around. Maybe it's good to destroy them rather than giving them to students or newbies.

Few days ago (28 May 2010), for example, we had a word-for-word copy of a book on a blog post (now removed) which was discussing MySQL Cluster limitations from years ago. Well, it was funny at first and we had a good laugh. But it's a bit worrisome. My colleague Matthew posted a rebuttal post.

How would you recycle the old, technical books? It's not worth giving them to public libraries, it's maybe unhealthy to burn them? How would you do it?

Having just written an interview response about NoSQL concepts for a RDBMS audience it was poetic that an inconspicuous title “(4 of 3)” highlights that both a MySQL read scalable implementation via replication and a NoSQL solution can share a common lack of timely consistency of data. For the sake of Group Commit I hope my data is always consistent at some location at some point in time as soon as possible.

In attempting to comment to Kristian Nielsen’s Fixing MySQL group commit (part 4 of 3) I was forced to watch an ad before I could even add a comment. Go jump Live Journal, it’s quicker to write my own blog post.

And if anybody is still reading, I had just written the following.

“There is clearly a place for NoSQL solutions. The two primary types of products are a key/value store and a schema-less solution. You need to learn …

Sorry for this not getting out sooner.  Connector/Net 6.3.2 was released several days ago but somehow the release announcement was never made. MySQL Connector/Net 6.3.2, a new version of the all-managed .NET driver for MySQL has been released. This is a beta release and is intended to introduce you to the new features and enhancements we are planning. This release should not be used in a production environment.  It is now available in source and binary form from [http://dev.mysql.com/downloads/connector/net/6.3.html] and mirror sites (note that not all mirror sites may be up to date at this point of time - if you can’t find this version on some mirror, please try again later or choose another download site.) The new features or changes in this release are:

• Visual Studio 2010 RTM support
• New sql editor.  Create a new file with a .mysql extension to see it in action

…

The Maatkit tools provide a suite of additional MySQL commands. There is one command I use constantly and that is mk-query-digest.

Unfortunately the documentation does leave a lot to be desired for usability. While throughout, it is a man page and not a user guide. Several of us have discussed writing better documentation however it’s always a matter of time. I have however learned a number of tips and I’d like to share them in smaller digests.

The first is showing additional display. Maatkit works on truncating per line output to a reasonable length of 73 characters?

One of those lines is the list of hosts that connected to MySQL for a query, for example.

# Hosts                  4 192.168.40... (2), 192.168.40... (2)... 2 more
# Hosts                  3 99.99.245.14 (12), …

In so many cases troubleshooting applications I keep thinking how much more efficient things could be going if only there would be a good instrumentation available. Most of applications out there have very little code to help understand what is going on and if it is there it is frequently looking at some metrics which are not very helpful.

If you look at the system from bird eye view - system needs to process transactions and you want it to successfully complete large number of transactions it gets (this is what called availability) and we want it to serve them with certain response time, which is what is called performance. There could be many variables in environment which change - load, number of concurrent users, database, the way users use the system but in the nutshell all what you really care is having predictable response time within certain range. So if we care about response time - this is exactly what our instrumentation should …

Original title was 'MySQL dropped from openSUSE!!!'. I wanted to have some shocking title, but I changed it as I don't really want to scare you so much But it is partially true, there is no mysql package in openSUSE anymore. But of course we DID NOT really dropped MySQL. In fact, we now have more MySQL in openSUSE then we ever had! Do I got your attention? Read on

What and why?

What really happened is that I renamed original MySQL package. Now it is called mysql-community-server. If you take a look at SUN/Oracle web, they call it like this for a long time, so it makes a little sense... As a result, there is no real package called mysql in openSUSE anymore. But mysql-community-server provides mysql so even if you try to install mysql, it will work. This change also have one funny consequence. Do you remember package mysql-client? Now it's called …

Original title was ‘MySQL dropped from openSUSE!!!‘. I wanted to have some shocking title, but I changed it as I don’t really want to scare you so much But it is partially true, there is no mysql package in openSUSE anymore. But of course we DID NOT really dropped MySQL. In fact, we now have more MySQL in openSUSE then we ever had! Do I got your attention? Read on

What and why?

What really happened is that I renamed original MySQL package. Now it is called mysql-community-server. If you take a look at SUN/Oracle web, they call it like this for a long time, so it makes a little sense… As a result, there is no real package called mysql in openSUSE anymore. But mysql-community-server provides mysql so even if you try to install mysql, it will work. This change also have one funny consequence. Do you remember package mysql-client? Now it’s …

How To Set Up WebDAV With MySQL Authentication On Apache2 (Ubuntu 9.10)

This guide explains how to set up WebDAV with MySQL authentication (using mod_auth_mysql) on Apache2 on an Ubuntu 9.10 server. WebDAV stands for Web-based Distributed Authoring and Versioning and is a set of extensions to the HTTP protocol that allow users to directly edit files on the Apache server so that they do not need to be downloaded/uploaded via FTP. Of course, WebDAV can also be used to upload and download files.

(No three-part series is complete without a part 4, right?)

Here is an analogy that describes well what group commit does. We have a bus driving back and forth transporting people from A to B (corresponding to fsync() "transporting" commits to durable storage on disk). The group commit optimisation is to have the bus pick up everyone that is waiting at A before driving to B, not drive people one by one. Makes sense, huh? :-)

It is pretty obvious that this optimisation of having more than one person in the bus can dramatically improve throughput, and it is the same for the group commit optimisation. Here is a graph from a benchmark comparing stock MariaDB 5.1 vs. MariaDB patched …