In case you have not already noticed, Workbench 5.2 alpha / preview release of MySQL's premier development and design tool, has been announced.

For an independent preview, you can also see here. 

Installation of MySQL Server on Linux (RedHat Enterprise Linux 5)

The recommended way to install MySQL on RPM-based Linux distributions is by using the RPM packages. The RPMs that MySQL/Sun provide to the community should work on all versions of Linux that support RPM packages and use glibc 2.3. You can download it from http://mirrors.sunsite.dk/mysql/downloads/mysql/5.1.html

Checking if MySQL is already installed & would be uninstalling it to install latest MySQL version

[root@localhost mysql]# rpm -qa | grep -i '^mysql-'
MySQL-python-1.2.1-1
mysql-5.0.22-2.1.0.1
mysql-server-5.0.22-2.1.0.1
mysql-connector-odbc-3.51.12-2.2

Un-installing older version of MySQL

[root@localhost mysql]# rpm --nodeps -ev MySQL-python-1.2.1-1
[root@localhost mysql]# rpm --nodeps -ev mysql-5.0.22-2.1.0.1
[root@localhost mysql]# rpm --nodeps -ev …

A really simple best practice:

Make sure there are NO mysql servers connected to the Cluster while you do the restore!
It can cause the restore to fail badly and potentially even your cluster.

Also, make sure (if you use disk data) to remove all data files in the datadirs of the data nodes as they are not removed when doing an --initial ... I have written a bug report about that...

(i will update the severalnines/config scipts to include this best practice!)

Restarts are required for certain, infrequent maintenance activities. Note that there is no loss of service while a single node restarts.

When a data node restarts, it first attempts to load the data into memory from the local log files and then it will catch up with any subsequent changes by retrieveing them from the surviving node(s) in its node group.

 Based on this, you would expect the time taken to restart a data node to be influenced by:

1. The amount of data that was stored on the data node before the restart
2. Rate of updates being made to the data during the restart
3. Network performance (assuming the data is being updated during recovery)

The times will also be influenced bycertain configuration parameters, performance of the host machine and whether the multi-threaded data node (ndbmtd) is being used.

To provide some insight into how these …

Do you need to find qps for peak hours not avg qps through mysql life.

The MySQL 5.1 offers new GLOBAL_STATUS information schema tables. These can be used to report certain performance metrics, such as the number of queries processed per certain seconds, NOT overall avg queries per second, Its good to know how much qps in peak hours.

http://forge.mysql.com/tools/tool.php?id=217

Sun's LAMP support is assembled from two pieces: the L is from our Linux/GNU Support (see SunSolve entry), while the AMP comes from the GlassFish WebStack, which, in its latest incarnation includes Apache HTTP Server, lighttpd, memcached, MySQL, PHP, Python, Ruby, Squid, Tomcat, GlassFish (v2.1) and Hudson (features).

The inclusion of Hudson is a bit of an opportunistic move (more on that in a bit), the rest comprises a well tested, integrated, …

When one wants to script automated replication chain building, certain things are quite annoying, like immutable replication configuration variables. For example, at certain moments log_slave_updates is more than needed, and thats what the server says:

mysql> show variables like 'log_slave_updates';
+-------------------+-------+
| Variable_name     | Value |
+-------------------+-------+
| log_slave_updates | OFF   |
+-------------------+-------+
1 row in set (0.00 sec)

mysql> set global log_slave_updates=1;
ERROR 1238 (HY000): Variable 'log_slave_updates' is a read only variable

Of course, there are few options, roll in-house fork (heheeeee!), restart your server, and keep warming up your tens of gigabytes of cache arenas, or wait for MySQL to ship a feature change in next major release. Then there are evil tactics:

mysql> system gdb -p $(pidof mysqld)
                       -ex "set opt_log_slave_updates=1" -batch …

Of course it’s not quite that simple. I’ve just decomissioned an old Red Hat 7.1 box (hosted dedicated server) that had been in service since 2002, so about 7 years. Specs? Celeron 1.3GHz, 512M, 60GB HD. Not too bad in the RAM and disk realm. It did a good job but goodness am I glad to be rid of it!

Not having that box online is safer for the planet, although it (perhaps amazingly considering the age of some of the externally facing software components) has never been compromised – I consider that mostly luck, by the way, I’m not naive about that. But it’s not easy to move off old servers, it’s generally (and also has been in this case) a lot of work.

Of course hosting has moved on since 2002, places like Linode offer more for less money/month. Of course they virtualise (Xen based in this case) and that’s not been my favourite (particularly for DB servers but depending …

In dbForge Studio for MySQL you can find Data Compare, a tool which allows you to compare and analyze tables data in databases, for example, to check that data in the synchronized databases are identical. Besides, it  allows synchronizing the data differences to get identical databases. The following picture illustrates comparison and synchronization of two MySQL databases.

Data Comparison Workflow

To compare data, the program automatically selects columns with a primary or unique key as comparison keys. Of course, you can set comparison keys manually, however, in such cases key repetition may occur which can cause conflicted records after comparison. Such records are not compared.

…

In case you have not already noticed, Workbench 5.2 alpha / preview release of MySQL's premier development and design tool, has been announced.

For an independent preview, you can also see here.