The main fixes in cmon 0.13 are:

• filtering of clusterlog
• better graphs interface with filtering
  
• fixed bug in load average graphs. Now the loadavg graphs works
• added replication role, socket when adding a mysql server to be monitored from the web interface.
  
• corrected bug with how often mysql_variables are collected
• fixed problems with graphs
• added images directory
• revamped graphs - now producing files in images directory,
• ajax support for Storage graphs
• divided helpers into smaller files

Upgrade from cmon 0.12

• Stop cmon 0.12 (e.g. killall cmon from the command line)
• Execute this sql script …

This is a simple mysql circular replication implementation on a single machine (just a proof of concept) which can easily be done on a broader scale. Just be aware of the cons of circular replication which mainly gets down to: once a node freaks out or stops for one reason or the other, it’s a bitch and you need to take care of IMMEDIATELY.

Download Sandbox from https://launchpad.net/mysql-sandbox/+download
Download MySQL from http://dev.mysql.com/downloads

Copy the downloaded software onto the your *nix box onto any folder of your preference called $BASEDIR

run:

cd /$BASEDIR

gunzip mysql_sandbox_X.X.XX.tar.gz
tar -xf mysql_sandbox_X.X.XX.tar

ln -s mysql_sandbox_X.X.XX sandbox

time /$BASEDIR/sandbox/make_replication_sandbox –circular=4 –topology=circular /$BASEDIR/mysql-5.1.30-linux-x86_64-glibc23.tar.gz


user@hostname $ time …

To be specific FTP is File Transfer Protocol and is around for over 30 years. FTP is the simplest and most secure way to exchange files over the Internet. Whether you know it or not, you most likely use FTP all the time. When downloading a file from the Internet you\'re actually transferring the file to your computer from another computer over the Internet. This is why the T (transfer) is in FTP. You may not know where the computer is that the file is coming from but you most likely know it\'s URL or Internet address.

Since MySQL Cluster 6.2 it is possible to setup a pool inside the mysqld process opening multiple connections to a MySQL Cluster. This is pretty cool, but it might give troubles when you have to use Single User Mode.
Take for example the following configuration for your SQL Nodes:

[SQL]
Id=10
Hostname= 10.100.9.6
[SQL]
Id=11
Hostname= 10.100.9.6
[SQL]
Id=12
Hostname= 10.100.9.7
[SQL]
Id=13
Hostname= 10.100.9.7

No further slots are defined, and you setup your two MySQL Servers to use connection pooling:

[mysqld]
ndb-cluster-connection-pool = 2

This will result in the following output of SHOW in the ndb_mgm client tool:

[mysqld(API)]   4 node(s)
id=10   @10.100.9.6  (mysql-5.1.30 ndb-6.3.20)
id=11   @10.100.9.6  (mysql-5.1.30 ndb-6.3.20)
id=12   @10.100.9.7 …

I am getting ready to FOSDEM, the biggest European gathering of free and open source software enthusiasts. The event is held in Brussels, Belgium, on February 7-8, 2009.

MySQL has a developers room on Sunday, with a schedule rich of well known names and juicy topics.

I will present a talk about partitions in MySQL 5.1.

Lenz will have a talk in the main conference, on MySQL high availability.

There is a wiki page on MySQL Forge where we will provide last minute information.

FOSDEM, the free and open source developer's meeting is just 9 days away.

I will be doing one talk on MySQL 5.1 Plugins on Sunday, February 8 in the MySQL Room. Initially I was scheduled for two talks, but one was canceled to make way for another talk. I'm actually quite happy it went that way, because Jurriaan Persyn's talk about Database Sharding that is now …

Actually, what I really wanted to blog about before getting carried away with irony yesterday was an old idea on how to force my developers to use placeholders exclusively for SQL queries in applications. As should be apparent from yesterdays blog entry, I am strongly in favour of using placeholders for interpolating values into SQL queries, due to the great reduction in potential bugs (including, but not limited to, SQL injections).

Basically, wrap the database API so that all database access passes through the wrapper. This can usually be achieved, for example by subclassing DBI (for Perl) and returning such subclasses from the application connection pool, or other similar methods. Probably many large web applications already have such wrappers or use APIs that can be patched or extended appropriately.

Now add code that basically bombs out with a big …