So some users complete a yum install of MySQL and expect to be able to use the following  command to start the MySQL server::  /etc/init.d/mysql start only to get "No such file or directory"
So this is a quick post to help use the systemctl command.  You are likely to see this: # systemctl list-unit-files | grep mysql
mysqld.service                              disabled
First I would recommend go to tools.percona.com and create a valid my.cnf file. 
So the solution is easy, we just need to enable this so the database can start on server start up.
#systemctl enable mysqld.service
ln -s '/usr/lib/systemd/system/mysqld.service' '/etc/systemd/system/mysql.service'
ln -s …

So, I’ve written previously on MySQL on POWER, and today is a quick bit of news about MySQL Cluster on POWER – specifically MySQL Cluster 7.3.7.

I ran into three main issues in getting some flexAsync benchmark results. One of them was the fact that I wanted to do this in the middle of all the POWER8 machines I usually use moving buildings (hard to run benchmarks when computers are packed up in boxes on a truck).

The next issue was that ndbmtd (the multi-threaded data node) needs memory barriers for the magic message passing stuff between threads. So, that’s pretty easy (about an eight line patch).

The next issue was in the results from flexAsync, it turns out 32bit math is a bad idea with results from my POWER8 box.

My preliminary performance numbers are fairly promising (actually… what is the world record for a single machine and NDB these days? Single data node?). I think there’s a bit more low …

The MySQL Server 5.7.5 Development Milestone Release includes support for acquiring multiple user-level locks within the same connection. The implementation of this feature is based on a contributed patch by Konstantin Osipov. This post tells the story about what happened with this patch on its way into the MySQL Server codebase.

If you are more interested in using this new functionality and the feature itself, rather than in the history behind it, then it is better to simply read the corresponding entry in the Release Notes or the updated documentation for the GET_LOCK() function.

Requests to extend the semantics of …

I visited MongoDB Day in London on November 6. Here are a few observations:

App-Developer Centric. It is interesting to see how much MongoDB is about developers; the ops side is something which is a necessary evil developers have to deal with. The ops topics covered in principle that there are no topics about choices of operating systems or hardware for MongoDB beyond flash and more memory.

Development Stacks. Being application centric there was good coverage of the MongoDB-powered stacks – MEAN and METEOR specifically got attention. Especially the METEOR presentation by Henrik Ingo was cool – real-time view synchronization between the Web browser (or mobile app) and database as well as the same language for server-side and client-side development is a really great concept. Though …

There are a few circumstances where one will not want to run with only MyISAM tables. In this case, it can be beneficial to completely disable InnoDB.

As InnoDB has become more prevalent, disabling it in MySQL requires a little more effort than before.

In MariaDB 10.0, you can still completely disable it as you have done in the past (just add the –skip-innodb option, specify default-storage-engine=MyISAM, and comment out other InnoDB options):

[mysqld]
skip-innodb
default-storage-engine=MyISAM

Alternatively, instead of –skip-innodb, you can instead use “innodb=OFF”:

[mysqld]
skip-innodb
default-storage-engine=MyISAM

In MySQL 5.6, the –skip-innodb option has been deprecated (though still currently works), and since InnoDB is the new “default” storage engine, you must set both “default-storage-engine” and the new “default-tmp-storage-engine” options to “MyISAM”. If you …

I know, what, MyISAM-only? Yes, it’s true, and it occurs more than you might think.

If you do run MyISAM-only, it’s common to have disabled InnoDB altogether (–skip-innodb) to avoid allocating any RAM to it, and to avoid unnecessary files required for backups, and so forth. (See this post if interested in disabling InnoDB in MySQL 5.6 and/or MariaDB 10.0.)

One improvement in MySQL 5.6 and MariaDB 10.0 is the addition of some system tables. The 2 that are in both are `innodb_table_stats` and `innodb_index_stats`, both of which have an engine type of InnoDB. (The 1 additional system table in MariaDB 10.0 is `gtid_slave_pos`, and the 3 additional system tables in MySQL 5.6 are `slave_master_info`, `slave_relay_log_info`, and `slave_worker_info`.)

The issue, with regards to running MyISAM-only, is that these new …

Oracle have just made availble the new MySQL Cluster 7.4.2 Development Milestone Release – it can be downloaded from the development release tab here. Note that this is not a GA release and so we wouldn’t recommend using it in production.

This is the second DMR for MySQL 7.4; the delta between this DMR and 7.4.1 can be viewed in the MySQL Cluster 7.4.2 Release Notes

There are three main focus areas for this DMR and the purpose of this post is to briefly introduce them:

• Active-Active (Multi-Master) Replication
• Performance
• Operational improvements (speeding up of restarts; enhanced …

The Perfect Server - Ubuntu 14.10 (nginx, BIND, Dovecot, ISPConfig 3)

This tutorial shows how to prepare an Ubuntu 14.10 (Utopic Unicorn) server (with nginx, BIND, Dovecot) for the installation of ISPConfig 3, and how to install ISPConfig 3. ISPConfig 3 is a webhosting control panel that allows you to configure the following services through a web browser: Apache or nginx web server, Postfix mail server, Courier or Dovecot IMAP/POP3 server, MySQL, BIND or MyDNS nameserver, PureFTPd, SpamAssassin, ClamAV, and many more. This setup covers nginx (instead of Apache), BIND (instead of MyDNS), and Dovecot (instead of Courier).

November 7, 2014 By Severalnines

PrestaShop is a popular open source e-commerce software powering over 200,000 online stores, according to the company. We’ve seen a bit of interest into high availability PrestaShop setups, so this post will show you how to achieve that on multiple servers. Note that this setup not only caters for failures, but by load balancing traffic across multiple servers, it also allows the system to scale and handle more users.

This post is similar to our previous posts on web application scalability and high availability:

• Magento - nginx, MySQL Galera Cluster, OCFS2
• Drupal - Apache, MySQL Galera Cluster, csync2 with …

Can you use the binary logs to undo a DELETE? Maybe, if you're using ROW format logging. The difference between a delete and an insert event could be just one byte - the one that maps it as a DELETE_ROWS_EVENT or a WRITE_ROWS_EVENT. Let's try it.

I've already populated this table with a few rows:

CREATE TABLE `undo_test` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`t` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`v` varchar(20) DEFAULT NULL,
`b` blob,
PRIMARY KEY (`id`)
) ENGINE=InnoDB;

Save a hash so we can see if the undo really works later:

mysql -e "SELECT * FROM test.undo_test" | md5sum > before.md5

Delete an unwanted row:

DELETE FROM undo_test;
Query OK, 1693 rows affected (0.14 sec)

Oops! Forgot the WHERE clause! And of course I don't have any recent …