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 …

Ubuntu 14.10 LAMP server tutorial with Apache 2, PHP 5 and MySQL (MariaDB)

LAMP is short for Linux, Apache, MySQL, PHP. This tutorial shows how you can install an Apache 2 webserver on an Ubuntu 14.10 server with PHP5 support (mod_php) and MySQL support. Additionally, I will install phpmyadmin to make MySQL administration easier. A LAMP setup is the perfect basis for CMS systems like Joomla, Wordpress or Drupal.

As described in the MySQL 5.7 manual here, we can now resize the buffer pool without restarting the mysqld process starting with MySQL 5.7.5.

You can now use the "SET GLOBAL innodb_buffer_pool_size = xxxx" command which causes a resizing job to begin in background. We can monitor the progress and state of the resizing work using the …

I ran into this the other day, and while the solution is documented in the manual, it was kind of buried, so I thought I’d mention it here (and hopefully make it easier for others searching for this in the future).

In this specific instance, one was running a huge LOAD DATA (10 hours into it) and had to terminate the LOAD DATA command.

Terminating the command is one thing, but preventing InnoDB from trying to undo the rows that were inserted is another.

In this case, the LOAD DATA will easily re-create the table in question, so the existing table can be “thrown out”, so to speak. This, of course, is a *critical* requirement for this operation (i.e., that you can easily re-create the table – either from a load, backup, dump, etc.).

Per the manual:

“If you know that a given table is causing a crash on rollback, you can drop it. You can also use this to stop a runaway rollback caused by a failing …